Herb & supplement monograph

Selenium Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Selenium interacts with medications. The heart of this page is the interaction list — every drug Selenium is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Selenium is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Selenium Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Selenium drug interaction appears low for most people. None of the listed interactions are rated major, and nearly all rest on lab, animal, or early-stage research rather than well-documented effects in humans.

Interactions deserving the most attention

The combinations that deserve the most care involve warfarin and other anticoagulant or antiplatelet drugs, since some human research suggests selenium can lengthen bleeding time. Selenium may also stimulate the immune system, which could theoretically work against immunosuppressants, a meaningful concern for transplant patients whose medicines are closely monitored. Animal research also hints selenium could prolong the sedating effect of barbiturates, though this has not been shown in people.

What the rest of the list means

Selenium appears alongside a long list of medications, but a big number does not mean every pairing is harmful. Most of these interactions are theoretical, based on possible effects on how the body clears certain medications or on immune activity. Where human data exists, such as with contraceptives or niacin, the effects were modest, conflicting, or of unclear real-world importance.

Check your medications against Selenium

Based on HelloPharmacist’s Selenium interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Selenium

321 medications have a known interaction with Selenium, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
6-mercaptopurinePurinethol
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + 6-mercaptopurine interaction 6-mercaptopurine drug page: uses, dosage & side effects
AbciximabReoPro
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Abciximab interaction
AbrocitinibCibinqo
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Abrocitinib interaction Abrocitinib drug page: uses, dosage & side effects
AcenocoumarolSintrom
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Acenocoumarol interaction
Acetaminophen, AspirinGemnisyn
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Acetaminophen, Aspirin interaction
Acetaminophen, Aspirin, CaffeineExcedrin, Excedrin Extra Strength, Excedrin Migraine
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Acetaminophen, Aspirin, Caffeine interaction
Acetaminophen, ButalbitalAxocet, Bancap, Bucet, Butex Forte, Esgic CF, Orbivan CF +5 more
Moderate Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.

Read the full Selenium + Acetaminophen, Butalbital interaction
Acetaminophen, Butalbital, CaffeineEsgic, Esgic Plus, Fiogesic, Fioricet, Repan, Tecnal +1 more
Moderate Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.

Read the full Selenium + Acetaminophen, Butalbital, Caffeine interaction Acetaminophen, Butalbital, Caffeine drug page: uses, dosage & side effects
Acetaminophen, Butalbital, Caffeine, CodeineEsgic with Codeine, Fioricet w/ Codeine
Moderate Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.

Read the full Selenium + Acetaminophen, Butalbital, Caffeine, Codeine interaction
Acetaminophen, IbuprofenCombogesic
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Acetaminophen, Ibuprofen interaction
Acetylsalicylic AcidEntrophen
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Acetylsalicylic Acid interaction Acetylsalicylic Acid drug page: uses, dosage & side effects
AdalimumabHumira
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Adalimumab interaction Adalimumab drug page: uses, dosage & side effects
Adalimumab-adazHyrimoz
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Adalimumab-adaz interaction
Adalimumab-adbmCyltezo
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Adalimumab-adbm interaction
Adalimumab-afzbAbrilada
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Adalimumab-afzb interaction
Adalimumab-attoAmjevita
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Adalimumab-atto interaction
Adalimumab-bwwdHadlima
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Adalimumab-bwwd interaction
Adalimumab-fkjpHulio
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Adalimumab-fkjp interaction
AlefaceptAmevive
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Alefacept interaction
AlemtuzumabCampath
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Alemtuzumab interaction Alemtuzumab drug page: uses, dosage & side effects
Alteplase, TpaActilyse, Activase
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Alteplase, Tpa interaction
Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #2
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium Hydroxide interaction
Aluminum Hydroxide, Aspirin, Magnesium HydroxideAscriptin
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Aluminum Hydroxide, Aspirin, Magnesium Hydroxide interaction Aluminum Hydroxide, Aspirin, Magnesium Hydroxide drug page: uses, dosage & side effects
Aminophylline, Amobarbital, EphedrineAmesec
Moderate Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.

Read the full Selenium + Aminophylline, Amobarbital, Ephedrine interaction
AmobarbitalAmytal
Moderate Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.

Read the full Selenium + Amobarbital interaction
Amobarbital, Ephedrine SulfateEphedrine & Amytal
Moderate Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.

Read the full Selenium + Amobarbital, Ephedrine Sulfate interaction
Amobarbital, SecobarbitalTuinal
Moderate Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.

Read the full Selenium + Amobarbital, Secobarbital interaction
Anacaulase-bcdbNexoBrid
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Anacaulase-bcdb interaction
AnagrelideAgrylin
Moderate Anticoagulant/antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full Selenium + Anagrelide interaction Anagrelide drug page: uses, dosage & side effects
Anifrolumab-fniaSaphnelo
Moderate Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.

Read the full Selenium + Anifrolumab-fnia interaction Anifrolumab-fnia drug page: uses, dosage & side effects
Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Selenium combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture

The kinds of drugs Selenium affects

Every type of medication (drug category) Selenium is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 6 drug categories Selenium interacts with
Anticoagulant/antiplatelet DrugsBarbituratesImmunosuppressantsWarfarin (coumadin)Contraceptive DrugsNiacin
Anticoagulant/Antiplatelet Drugs

Selenium may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Clinical research suggests that taking selenium 10 mcg/kg/day can increase bleeding times by increasing prostacyclin production, which inhibits platelet activity. Other clinical research suggests that taking selenium 75 mcg daily, in combination with ascorbic acid 600 mg, alpha-tocopherol 300 mg, and beta-carotene 27 mg, reduces platelet aggregation.

Likelihood Possible Evidence D
Barbiturates

Theoretically, selenium might prolong the sedating effects of barbiturates.
Laboratory research suggests that selenium can inhibit the hepatic metabolism of barbiturates. Selenium seems to prolong the sedative effect of pentobarbital in animal models.

Likelihood Possible Evidence D
Immunosuppressants

Theoretically, selenium supplementation may reduce the effectiveness of immunosuppressant therapy.
In vitro research and preliminary clinical evidence suggests that selenium may stimulate the immune system.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, selenium might interfere with warfarin activity.
Animal research suggests that selenium can increase warfarin activity. Selenium might interact with warfarin by displacing it from albumin binding sites, reducing its metabolism in the liver, or by decreasing production of vitamin K-dependent clotting factors. Selenium can also prolong bleeding times in humans by increasing prostacyclin production, which inhibits platelet activity.

Likelihood Possible Evidence D
Contraceptive Drugs

Contraceptive drugs might increase levels of selenium, although the clinical significance of this effect is unclear.
Some research suggests that oral contraceptives increase serum selenium levels in women taking oral contraceptives; however, other research shows no change in selenium levels. It is suggested that an increase could be due to increased carrier proteins, indicating a redistribution of selenium rather than a change in total body selenium.

Likelihood Possible Evidence B
Niacin

Selenium might reduce the beneficial effects of niacin on high-density lipoprotein (HDL) levels.
A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease. It is not known whether this adverse effect is due to a single antioxidant such as selenium, or to the combination. It also is not known whether it will occur in other patient populations.

Likelihood Possible Evidence A
Monograph

Selenium: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

Selenium is an essential trace mineral your body needs in small amounts for thyroid function, antioxidant defense, and immune health. Most people who eat a varied diet get enough, and supplements are mainly useful for those who are deficient. Because too much selenium can be toxic, stick to recommended amounts and check with your pharmacist or doctor before supplementing.

Part used
Not applicable (selenium is a mineral, not a plant)
Common forms
Tablets, capsules, softgels, multivitamin/mineral products; common forms include selenomethionine, sodium selenite, and selenium-enriched yeast
People commonly use it for
  • Thyroid health support
  • Antioxidant support
  • Immune support
  • General nutrient supplementation
  • Reproductive/fertility support

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

Safe in small recommended amounts, but excess selenium can be toxic.

PregnancyPossibly Safe

When used orally and appropriately. Selenium appears to be safe when used short-term in amounts that do not exceed the tolerable upper intake level (U...

Read the full pregnancy detail
BreastfeedingPossibly Safe

When used orally and appropriately. Selenium appears to be safe when used short-term in amounts that do not exceed the tolerable upper intake level (U...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Selenium is an essential trace mineral, which means your body needs only a small amount but cannot function properly without it. Unlike herbs, it is not made from a plant. It is found naturally in soil and water, and it makes its way into our diet through foods grown in that soil.

Good dietary sources include Brazil nuts, seafood, organ meats, eggs, poultry, and whole grains. The amount of selenium in plant foods depends a lot on how much selenium is in the soil where they grew, so levels vary from region to region.

People take selenium supplements to make sure they get enough, to support thyroid and immune health, and for its antioxidant properties. Most people who eat a balanced diet already get the selenium they need.

How it works

Selenium is used by the body to build special proteins called selenoproteins. Many of these act as antioxidant enzymes (such as glutathione peroxidases) that help protect cells from damage caused by unstable molecules called free radicals.

Selenium is also needed to make enzymes (deiodinases) that help convert thyroid hormone into its active form. This is why it plays an important role in thyroid function.

It also supports the normal working of the immune system. Much of the detailed mechanism comes from laboratory and animal research, and having more selenium than your body needs does not make these systems work better.

Effectiveness

Does Selenium work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 77 uses evaluated
1 Likely effective 3 Possibly effective 13 Leans ineffective 60 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.
Likely Effective Selenium deficiency
Rating & evidence shown verbatim from Natural Medicines

Oral selenium is effective for the treatment and prevention of selenium deficiency.

Possibly Effective Autoimmune thyroiditis
Rating & evidence shown verbatim from Natural Medicines

Oral selenium seems to improve autoimmune thyroiditis in adults, but the evidence of benefit in children is conflicting.

Possibly Effective Kashin-Beck disease
Rating & evidence shown verbatim from Natural Medicines

Selenium seems to help prevent Kashin-Beck disease, but does not improve symptoms in patients with existing disease.

Possibly Effective Pre-eclampsia
Rating & evidence shown verbatim from Natural Medicines

Oral selenium might reduce the risk of pre-eclampsia in pregnant patients.

Possibly Ineffective Asthma
Rating & evidence shown verbatim from Natural Medicines

Oral selenium does not seem to improve asthma symptoms.

Possibly Ineffective Atopic dermatitis (eczema)
Rating & evidence shown verbatim from Natural Medicines

Oral selenium-enriched yeast does not seem to improve eczema symptoms.

Possibly Ineffective Cardiovascular disease (CVD)
Rating & evidence shown verbatim from Natural Medicines

Most research shows that oral selenium does not reduce the risk of CVD.

Possibly Ineffective Colorectal cancer
Rating & evidence shown verbatim from Natural Medicines

Oral selenium does not seem to prevent cancer of the colon and rectum.

Possibly Ineffective Dyslipidemia
Rating & evidence shown verbatim from Natural Medicines

Most research shows that oral selenium supplementation does not improve cholesterol levels.

Possibly Ineffective Low birth weight
Rating & evidence shown verbatim from Natural Medicines

Oral or intravenous selenium supplementation does not improve outcomes in low birth weight infants.

Possibly Ineffective Lung cancer
Rating & evidence shown verbatim from Natural Medicines

Oral selenium does not reduce lung cancer risk in most patients.

Possibly Ineffective Nonmelanoma skin cancer
Rating & evidence shown verbatim from Natural Medicines

Oral selenium does not reduce the risk of nonmelanoma skin cancer and has been linked to increased risk in some patients.

Possibly Ineffective Prostate cancer
Rating & evidence shown verbatim from Natural Medicines

Oral selenium does not seem to reduce prostate cancer risk.

Possibly Ineffective Psoriasis
Rating & evidence shown verbatim from Natural Medicines

Oral selenium does not seem to reduce psoriasis severity.

Possibly Ineffective Sepsis
Rating & evidence shown verbatim from Natural Medicines

Intravenous selenium does not appear to improve outcomes in septic adults.

Likely Ineffective Bladder cancer
Rating & evidence shown verbatim from Natural Medicines

Despite promising initial research, oral selenium does not seem to prevent the development, recurrence, or progression of bladder cancer.

Likely Ineffective Diabetes
Rating & evidence shown verbatim from Natural Medicines

Increased intake of selenium, either in the diet or as a supplement, is associated with an increased risk for developing type 2 diabetes. It is unclear if oral selenium is beneficial in patients with type 2 diabetes.

Also studied for 60 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Age-related cognitive decline
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces the risk of cognitive decline in older adults.

Insufficient Reliable Evidence To Rate Alcohol-related liver disease
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral selenium for alcohol-related liver disease, there is insufficient reliable information about the clinical effects of selenium for this condition.

Insufficient Reliable Evidence To Rate Allergic rhinitis (hay fever)
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral selenium for allergic rhinitis, there is insufficient reliable information about the clinical effects of selenium for this condition.

Insufficient Reliable Evidence To Rate Alzheimer disease
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Androgenic alopecia
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Arsenic poisoning
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenized yeast is beneficial for patients that were exposed to high levels of arsenic in the environment.

Insufficient Reliable Evidence To Rate Benign prostatic hyperplasia (BPH)
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Burns
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Cataracts
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Cervical dysplasia
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenized yeast is beneficial for patients with cervical dysplasia of mild severity.

Insufficient Reliable Evidence To Rate Chemotherapy-induced nephrotoxicity
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Chronic fatigue syndrome (CFS)
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral selenium for CFS, there is insufficient reliable information about the clinical effects of selenium for this condition.

Insufficient Reliable Evidence To Rate Cirrhosis
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Cisplatin-associated ototoxicity
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Colorectal adenoma
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium prevents recurrence of adenomas in the colon and rectum.

Insufficient Reliable Evidence To Rate Congestive heart failure (CHF)
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Coronary artery bypass graft (CABG) surgery
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenized yeast is beneficial for patients undergoing CABG surgery.

Insufficient Reliable Evidence To Rate Critical illness (trauma)
Rating & evidence shown verbatim from Natural Medicines

Evidence on the use of intravenous selenium in critically ill patients is conflicting.

Insufficient Reliable Evidence To Rate Dementia
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium prevents dementia or reduces symptoms.

Insufficient Reliable Evidence To Rate Depression
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for the treatment of prevention of depression.

Insufficient Reliable Evidence To Rate Diabetic nephropathy
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium alleviates diabetic nephropathy symptoms.

Insufficient Reliable Evidence To Rate Dilated cardiomyopathy
Rating & evidence shown verbatim from Natural Medicines

There is limited evidence on the oral use of selenium in patients with Keshan disease and peripartum cardiomyopathy.

Insufficient Reliable Evidence To Rate Esophageal cancer
Rating & evidence shown verbatim from Natural Medicines

Limited research suggests that oral selenium does not reduce esophageal cancer risk.

Insufficient Reliable Evidence To Rate Gastric cancer
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients and in a specific patient population; its effect when used alone and in other populations is unclear.

Insufficient Reliable Evidence To Rate Hepatitis C
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate HIV/AIDS
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium improves outcomes in patients with HIV.

Insufficient Reliable Evidence To Rate Hypertension
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium improves blood pressure. Some evidence suggests selenium supplementation may slightly increase systolic blood pressure.

Insufficient Reliable Evidence To Rate Hyperthyroidism
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium alleviates symptoms in patients with Graves' disease.

Insufficient Reliable Evidence To Rate Hypothyroidism
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium improves thyroid hormone balance in elderly individuals, pregnant patients, or patients with subclinical hypothyroidism. In patients with iodine deficiency, selenium supplementation may be harmful.

Insufficient Reliable Evidence To Rate Influenza
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral selenium for influenza, there is insufficient reliable information about the clinical effects of selenium for this condition.

Insufficient Reliable Evidence To Rate Kidney failure
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for improving lipid parameters in patients on hemodialysis.

Insufficient Reliable Evidence To Rate Lichen planus
Rating & evidence shown verbatim from Natural Medicines

It is unclear if topical or oral selenium alleviates oral lichen planus symptoms.

Insufficient Reliable Evidence To Rate Liver cancer
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces liver cancer risk.

Insufficient Reliable Evidence To Rate Lymphedema
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces lymphedema complications.

Insufficient Reliable Evidence To Rate Male infertility
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium, used alone or in combination with other antioxidants, improves pregnancy or live birth rates for couples with idiopathic male infertility.

Insufficient Reliable Evidence To Rate Mercury toxicity
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium improves clearance of mercury and reduces symptoms of toxicity.

Insufficient Reliable Evidence To Rate Muscular dystrophy
Rating & evidence shown verbatim from Natural Medicines

There is limited evidence on the oral use of selenium in Duchenne muscular dystrophy.

Insufficient Reliable Evidence To Rate Obesity
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for weight reduction.

Insufficient Reliable Evidence To Rate Oral mucositis
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for reducing oral mucositis in patients undergoing radiotherapy.

Insufficient Reliable Evidence To Rate Osteoarthritis
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Ovarian cancer
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces ovarian cancer risk.

Insufficient Reliable Evidence To Rate Overall mortality
Rating & evidence shown verbatim from Natural Medicines

Although oral selenium does not seem to reduce overall mortality risk in most patients, it might have benefit in patients with low nutrient intake.

Insufficient Reliable Evidence To Rate Pancreatic cancer
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces pancreatic cancer risk.

Insufficient Reliable Evidence To Rate Pancreatitis
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral selenium for pancreatitis, there is insufficient reliable information about the clinical effects of selenium for this condition.

Insufficient Reliable Evidence To Rate Periodontitis
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Polycystic ovary syndrome (PCOS)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for PCOS.

Insufficient Reliable Evidence To Rate Postoperative recovery
Rating & evidence shown verbatim from Natural Medicines

It is unclear if intravenous sodium selenite reduces morbidity and mortality in cardiac surgery patients.

Insufficient Reliable Evidence To Rate Postpartum depression
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for postpartum depression.

Insufficient Reliable Evidence To Rate Pregnancy-induced hypertension
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces the development of hypertension during pregnancy.

Insufficient Reliable Evidence To Rate Premature rupture of membranes (PROM)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium during pregnancy prevents PROM.

Insufficient Reliable Evidence To Rate Radiation-induced diarrhea
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces diarrhea in patients receiving radiation therapy for cancer.

Insufficient Reliable Evidence To Rate Rheumatoid arthritis (RA)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces RA symptoms.

Insufficient Reliable Evidence To Rate Schizophrenia
Rating & evidence shown verbatim from Natural Medicines

Oral selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Seborrheic dermatitis
Rating & evidence shown verbatim from Natural Medicines

It is unclear if topical selenium disulfide shampoo is beneficial for seborrheic dermatitis.

Insufficient Reliable Evidence To Rate Statin-induced myopathy
Rating & evidence shown verbatim from Natural Medicines

Small clinical studies suggest that oral selenium may not improve symptoms of myopathy in patients taking statins.

Insufficient Reliable Evidence To Rate Stroke
Rating & evidence shown verbatim from Natural Medicines

It is unclear if intravenous selenium improves neurological outcomes following a stroke.

Insufficient Reliable Evidence To Rate Subarachnoid hemorrhage
Rating & evidence shown verbatim from Natural Medicines

Intravenous selenium has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Succinylcholine-induced myalgia
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for preventing succinylcholine-induced postoperative myalgia.

Insufficient Reliable Evidence To Rate Thyroid cancer
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium reduces the risk of thyroid cancer in most patients.

Insufficient Reliable Evidence To Rate Ulcerative colitis
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral selenium is beneficial for ulcerative colitis.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

At the small amounts found in food and standard supplements, selenium is generally safe for most adults. The main concern is too much. Selenium has a relatively narrow gap between a helpful amount and a harmful one, so high-dose supplements should be avoided unless a healthcare provider recommends them.

A single Brazil nut can contain a large amount of selenium, so eating many of them daily plus taking a supplement can add up quickly. People taking multiple supplements should check the total selenium across all products.

Pregnancy and breastfeeding: getting selenium in normal dietary amounts (including a prenatal vitamin with standard levels) is generally considered acceptable, but high-dose selenium supplements should be avoided unless your doctor specifically advises them. When in doubt, choose caution and ask your pharmacist or doctor.

Side effects

At normal amounts, side effects are uncommon. Taking too much selenium over time can cause a condition called selenosis. Signs include a garlic-like odor on the breath, a metallic taste, hair loss, brittle nails, skin rash, nausea, diarrhea, fatigue, and irritability.

In severe cases of overdose, more serious effects on the nervous system, kidneys, and heart can occur. If you notice unusual hair or nail changes or a persistent garlic-like breath odor while taking selenium, stop and speak with a healthcare provider.

Selenium: Reported Adverse Effects

Documented safety reports on Selenium from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, selenium is generally well-tolerated when used in doses that do not exceed the tolerable upper intake level (UL) of 400 mcg daily. Intravenously, selenium is generally well-tolerated.

Most Common Adverse Effects:

Orally: Gastric discomfort, headache, and rash. Excessive amounts can cause alopecia, dermatitis, fatigue, nail changes, nausea and vomiting, and weight loss.

Serious Adverse Effects (Rare):

Orally: Excessive ingestion has led to cases of multi-organ failure and death.

Reports by condition
Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease) Neurologic/CNS

Chronic exposure to organic and inorganic selenium may cause neurotoxicity, particularly motor neuron degeneration, leading to an increased risk of amyotrophic lateral sclerosis (ALS). Headache has been reported in patients taking up to 200 mcg of selenium daily for up to 12 months and in patients taking sodium selenate 30 mg daily for up to 24 weeks.

  1. Vinceti, M., Wei, E. T., Malagoli, C., Bergomi, M., and Vivoli, G. Adverse health effects of selenium in humans. Rev.Environ.Health 2001;16(4):233-251.
  2. Wichman J, Winther KH, Bonnema SJ, Hegedüs L. Selenium supplementation significantly reduces thyroid autoantibody levels in patients with chronic autoimmune thyroiditis: a systematic review and meta-analysis. Thyroid 2016;26(12):1681-92.
  3. Malpas CB, Vivash L, Genc S, et al. A Phase IIa Randomized Control Trial of VEL015 (Sodium Selenate) in Mild-Moderate Alzheimer's Disease. J Alzheimers Dis. 2016;54(1):223-232.
Cancer Dermatologic

Excess selenium can produce selenosis in humans, affecting liver, skin, nails, and hair as well as dermatitis. Results from the Nutritional Prevention of Cancer Trial conducted among individuals at high risk of nonmelanoma skin cancer demonstrate that selenium supplementation is ineffective at preventing basal cell carcinoma and that it increases the risk of squamous cell carcinoma and total nonmelanoma skin cancer. Mild skin rash has been reported in patients taking up to 200 mcg of selenium daily for up to 12 months.

  1. Vinceti, M., Wei, E. T., Malagoli, C., Bergomi, M., and Vivoli, G. Adverse health effects of selenium in humans. Rev.Environ.Health 2001;16(4):233-251.
  2. Abrams, C. K., Siram, S. M., Galsim, C., Johnson-Hamilton, H., Munford, F. L., and Mezghebe, H. Selenium deficiency in long-term total parenteral nutrition. Nutr Clin Pract 1992;7(4):175-178.
  3. Alexander, J. Selenium. Novartis.Found.Symp 2007;282:143-149.
  4. Srivastava, A. K., Gupta, B. N., Bihari, V., and Gaur, J. S. Generalized hair loss and selenium exposure. Vet.Hum.Toxicol. 1995;37(5):468-469.
  5. Rees K, Hartley L, Day C, et al. Selenium supplementation for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev 2013;1:CD009671.
  6. Malpas CB, Vivash L, Genc S, et al. A Phase IIa Randomized Control Trial of VEL015 (Sodium Selenate) in Mild-Moderate Alzheimer's Disease. J Alzheimers Dis. 2016;54(1):223-232.
  7. Duffield-Lillico AJ, Slate EH, Reid ME, et al. Selenium supplementation and secondary prevention of nonmelanoma skin cancer in a randomized trial. J Natl Cancer Inst 2003;95:1477-81..
  8. Wichman J, Winther KH, Bonnema SJ, Hegedüs L. Selenium supplementation significantly reduces thyroid autoantibody levels in patients with chronic autoimmune thyroiditis: a systematic review and meta-analysis. Thyroid 2016;26(12):1681-92.
Diabetes Endocrine

Multiple clinical studies have found an association between increased intake of selenium, either in the diet or as a supplement, and the risk for type 2 diabetes. One meta-analysis shows that a selenium plasma level of 90 mcg/L or 140 mcg/L is associated with a 50% or 260% increased risk for developing type 2 diabetes, respectively, when compared with plasma levels below 90 mcg/L. Additionally, consuming selenium in amounts exceeding the recommended dietary allowance (RDA) is associated with an increased risk of developing diabetes when compared with consuming less than the RDA daily. Also, taking selenium 200 mcg daily as a supplement is associated with an 11% increased risk for diabetes when compared with a placebo supplement.

Hypothyroidism, secondary to iodine deficiency, has been reported as a result of selenium intravenous administration. One large human clinical trial suggested a possible increased risk of type 2 diabetes mellitus in the selenium group.

  1. Thompson PA, Ashbeck EL, Roe DJ, et al. Selenium Supplementation for Prevention of Colorectal Adenomas and Risk of Associated Type 2 Diabetes. J Natl Cancer Inst. 2016;108(12).
  2. Vinceti M, Filippini T, Rothman KJ. Selenium exposure and the risk of type 2 diabetes: a systematic review and meta-analysis. Eur J Epidemiol. 2018 Sep;33(9):789-810. Epub 2018 Jul 5. Review.
  3. Contempre B, Dumont JE, Ngo B, et al. Effect of selenium supplementation in hypothyroid subjects of an iodine and selenium deficient area: the possible danger of indiscriminate supplementation of iodine-deficient subjects with selenium. J Clin Endocrinol
  4. Hofbauer LC, Spitzweg C, Magerstadt RA, Heufelder AE. Selenium-induced thyroid dysfunction. Postgrad Med J 1997;73:103-4.
  5. Lippmann SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the selenium and vitamin E cancer prevention trial (SELECT). JAMA 2009;301:39-51.
Myalgia Musculoskeletal

Chronic selenium exposure of 30 mg daily for up to 24 weeks may cause arthralgia, myalgia, and muscle spasms.

  1. Malpas CB, Vivash L, Genc S, et al. A Phase IIa Randomized Control Trial of VEL015 (Sodium Selenate) in Mild-Moderate Alzheimer's Disease. J Alzheimers Dis. 2016;54(1):223-232.
Nausea and vomiting Gastrointestinal

In human research, nausea, vomiting, and liver dysfunction has been reported as a result of high selenium exposure. Mild gastric discomfort has been reported in patients taking up to 200 mcg of selenium daily for up to 12 months.

  1. Kamble, P., Mohsin, N., Jha, A., Date, A., Upadhaya, A., Mohammad, E., Khalil, M., Pakkyara, A., and Budruddin, M. Selenium intoxication with selenite broth resulting in acute renal failure and severe gastritis. Saudi.J Kidney Dis.Transpl. 2009;20(1):106
  2. Spiller, H. A. and Pfiefer, E. Two fatal cases of selenium toxicity. Forensic Sci Int 8-24-2007;171(1):67-72.
  3. Malpas CB, Vivash L, Genc S, et al. A Phase IIa Randomized Control Trial of VEL015 (Sodium Selenate) in Mild-Moderate Alzheimer's Disease. J Alzheimers Dis. 2016;54(1):223-232.
  4. Wichman J, Winther KH, Bonnema SJ, Hegedüs L. Selenium supplementation significantly reduces thyroid autoantibody levels in patients with chronic autoimmune thyroiditis: a systematic review and meta-analysis. Thyroid 2016;26(12):1681-92.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

Selenium needs are usually measured in micrograms (mcg) per day, and recommended amounts differ by age and life stage. Most adults need only a small daily amount, which many people already get from food. Health authorities also set an upper limit for safe daily intake that should not be exceeded.

Because the right amount depends on your diet, health, and whether you are actually deficient, there is no single dose that fits everyone. Follow the product label and avoid stacking multiple products that all contain selenium. Talk with your pharmacist or doctor to find out whether you need a supplement and how much is appropriate for you.

Pregnancy & Breastfeeding

Selenium & Pregnancy

Possibly Safe

When used orally and appropriately. Selenium appears to be safe when used short-term in amounts that do not exceed the tolerable upper intake level (UL) of 400 mcg daily; however, there is concern that long-term use might not be safe.

  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.
  2. Reid SM, Middleton P, Cossich MC, Crowther CA. Interventions for clinical and subclinical hypothyroidism in pregnancy. Cochrane Database Syst Rev 2010;(7):CD007752.
  3. Kupka, R., Mugusi, F., Aboud, S., Msamanga, G. I., Finkelstein, J. L., Spiegelman, D., and Fawzi, W. W. Randomized, double-blind, placebo-controlled trial of selenium supplements among HIV-infected pregnant women in Tanzania: effects on maternal and chil
  4. Han, L. and Zhou, S. M. Selenium supplement in the prevention of pregnancy induced hypertension. Chin Med J (Engl) 1994;107(11):870-871.
  5. Negro, R., Greco, G., Mangieri, T., Pezzarossa, A., Dazzi, D., and Hassan, H. The influence of selenium supplementation on postpartum thyroid status in pregnant women with thyroid peroxidase autoantibodies. J Clin Endocrinol.Metab 2007;92(4):1263-1268.
Possibly Unsafe

When used orally in excessive doses. Doses above 400 mcg daily may cause significant toxicity.

  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.

Selenium & Breastfeeding

Possibly Safe

When used orally and appropriately. Selenium appears to be safe when used short-term in amounts that do not exceed the tolerable upper intake level (UL) of 400 mcg daily when taken short-term; however, there is concern that long-term use might not be safe.

  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.
  2. Kumpulainen, J., Salmenpera, L., Siimes, M. A., Koivistoinen, P., and Perheentupa, J. Selenium status of exclusively breast-fed infants as influenced by maternal organic or inorganic selenium supplementation. Am.J Clin.Nutr. 1985;42(5):829-835.
Possibly Unsafe

When used orally in excessive doses. Doses above 400 mcg daily may cause significant toxicity. ...when used orally in HIV-positive women. Selenium supplementation in HIV-positive women not taking highly active antiretroviral therapy may increase HIV-1 levels in breast milk.

  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.
  2. Trafikowska U, Zachara BA, Wiacek M, et al. Selenium supply and glutathione peroxidase activity in breastfed Polish infants. Acta Paediatr 1996;85:1143-5.
  3. Sudfeld CR, Aboud S, Kupka R, et al. Effect of selenium supplementation on HIV-1 RNA detection in breast milk of Tanzanian women. Nutrition 2014;30(9):1081-4.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 36 references that drive our Selenium monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.
  2. Brown BG, Zhao XQ, Chait A, et al. Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease. N Engl J Med 2001;345:1583-93. DOI
  3. Trafikowska U, Zachara BA, Wiacek M, et al. Selenium supply and glutathione peroxidase activity in breastfed Polish infants. Acta Paediatr 1996;85:1143-5. PubMed
  4. Duffield-Lillico AJ, Slate EH, Reid ME, et al. Selenium supplementation and secondary prevention of nonmelanoma skin cancer in a randomized trial. J Natl Cancer Inst 2003;95:1477-81.. PubMed
  5. Cheung MC, Zhao XQ, Chait A, et al. Antioxidant supplements block the response of HDL to simvastatin-niacin therapy in patients with coronary artery disease and low HDL. Arterioscler Thromb Vasc Biol 2001;21:1320-6. PubMed
  6. Schiavon R, Freeman GE, Guidi GC, et al. Selenium enhances prostacyclin production by cultured endothelial cells: possible explanation for increased bleeding times in volunteers taking selenium as a dietary supplement. Thromb Res 1984;34:389-96. PubMed
  7. Davila JC, Edds GT, Osuna O, Simpson CF. Modification of the effects of aflatoxin B1 and warfarin in young pigs given selenium. Am J Vet Res 1983;44:1877-83. DOI
  8. Heese HD, Lawrence MA, Dempster WS, Pocock F. Reference concentrations of serum selenium and manganese in healthy nulliparas. S Afr Med J 1988;73:163-5.
  9. Lloyd B, Lloyd RS, Clayton BE. Effect of smoking, alcohol and other factors on the selenium status of a healthy population. J Epidemiol Commun Health 1983;37:213-7. PubMed
  10. Capel ID, Jenner M, Williams DC, et al. The effect of prolonged oral contraceptive steroid use on erythrocyte glutathione peroxidase activity. J Steroid Biochem 1981;14:729-32. PubMed
  11. Contempre B, Dumont JE, Ngo B, et al. Effect of selenium supplementation in hypothyroid subjects of an iodine and selenium deficient area: the possible danger of indiscriminate supplementation of iodine-deficient subjects with selenium. J Clin Endocrinol PubMed
  12. Hofbauer LC, Spitzweg C, Magerstadt RA, Heufelder AE. Selenium-induced thyroid dysfunction. Postgrad Med J 1997;73:103-4. PubMed
  13. Debski B, Milner JA. Dietary selenium supplementation prolongs pentobarbital induced hypnosis. J Nutr Biochem 2004;15:548-53. PubMed
  14. Ishikawa M, Sasaki M, Koiwai K, et al. Inhibition of hepatic mixed-function oxidase enzymes in mice by acute and chronic treatment with selenium. J Pharmacobiodyn 1992;15:377-85. PubMed
  15. Lippmann SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the selenium and vitamin E cancer prevention trial (SELECT). JAMA 2009;301:39-51. DOI
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Brand directory

Brands that make products with Selenium

1,591 brands in our database make a supplement containing Selenium.

Product directory

Supplement products with Selenium

16,950 products in our database contain Selenium. Open any to see its full ingredient list and every drug interaction we check.

+E Boost Vita-E 268 mg by Shaklee Tablet Or Pill 90 Tablet(s) View ingredients & interactions +E Boost Vita-E Complex by Shaklee Softgel Capsule 90 Softgel(s) View ingredients & interactions +Immunity Immunity Formula I by Shaklee Capsule 60 Capsule(s) View ingredients & interactions 1 Vitamin + Mineral by Pioneer Tablet Or Pill 120 Vegetarian Tablet(s) View ingredients & interactions 100% Natural E-400 IU With Selenium 50 mcg by Vitamin World Softgel Capsule 250 Rapid Release Softgel(s) View ingredients & interactions 100% Plant-Based Protein Nutritional Shake Very Berry by Purely Inspired Powder 1.5 lbs · 680 Gram(s) View ingredients & interactions 100% Vegan Complete MultiVitamin by Purely Inspired Tablet Or Pill 90 Vegan Tablet(s) View ingredients & interactions 100% Whole Food Prenatal by Whole Body Research Capsule 120 Vegetarian Capsule(s) View ingredients & interactions 10x Pure Ultimate Multi-Vitamin & Mineral Supplement by CTFO Changing The Future Outcome Capsule 60 Capsule(s) View ingredients & interactions 2-in-1 Kidney & Liver Super Cleanse by Irwin Naturals Softgel Capsule 60 Liquid Soft-Gel(s) View ingredients & interactions 2/A Day Multi by Adaptogen Research Capsule 60 Vegetarian Capsule(s) View ingredients & interactions 21 Multi by Somaplex Liquid 3.38 fl. Oz. · 100 mL View ingredients & interactions 3 en 1 by Bellodec-tta Tablet Or Pill 60 Tablet(s) View ingredients & interactions 3-Day Liver Cleanse Morning Formula by Renew Life Capsule 6 Vegetarian Capsule(s) View ingredients & interactions 30 Day Beauty Regimen by Bronson Tablet Or Pill 30 Packet(s) View ingredients & interactions 40+ Every Man II Multivitamin by New Chapter Tablet Or Pill 48 Tablet(s) View ingredients & interactions 40+ Every Man II Multivitamin by New Chapter Tablet Or Pill 96 Tablet(s) View ingredients & interactions 40+ Every Man's One Daily Multi by New Chapter Tablet Or Pill 24 Tablet(s) View ingredients & interactions 40+ Every Man's One Daily Multi by New Chapter Tablet Or Pill 96 Vegetarian Tablet(s) View ingredients & interactions 40+ Every Woman II Multivitamin by New Chapter Tablet Or Pill 48 Tablet(s) View ingredients & interactions 40+ Every Woman's One Daily Multi by New Chapter Tablet Or Pill 24 Tablet(s) View ingredients & interactions 40+ Every Woman's One Daily Whole Food Multivitamin by New Chapter Tablet Or Pill 96 Vegetarian Tablet(s) View ingredients & interactions 40+ Every Woman's One Daily Whole-Food Multivitamin by New Chapter Tablet Or Pill 72 Vegetarian Tablet(s) View ingredients & interactions 40+ Every Woman's One Daily Whole-Food Multivitamin by New Chapter Tablet Or Pill 48 Vegetarian Tablet(s) View ingredients & interactions
Drug-induced depletion

Medications associated with Selenium depletion

27 medications in our licensed clinical database have been associated with lower Selenium levels. An association is not a guarantee — it is a talking point for your pharmacist.

See all medications that may deplete Selenium

Pharmacist Counseling Corner

Selenium: Common Questions

What is Selenium used for, and does it work?
People use Selenium for many reasons, but the evidence varies by use. According to the Natural Medicines database, there is at least some clinical evidence supporting Selenium for Selenium deficiency, Autoimmune thyroiditis, Kashin-Beck disease and Pre-eclampsia. For most other uses it has been studied for, the evidence is currently insufficient to rate. See the graded list on this page, and always confirm with your pharmacist or doctor.
Does Selenium interact with prescription medications?
Yes. We list 321 medications with a known interaction with Selenium. Use the checker above to see how Selenium interacts with a specific drug.
How are Selenium interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Selenium with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Selenium interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Selenium used for?
Selenium is an essential mineral needed for thyroid function, antioxidant protection, and immune health. People most often supplement it to correct a deficiency or as part of a multivitamin.
Do I need a Selenium supplement?
Most people who eat a varied diet get enough Selenium from foods like seafood, meat, eggs, and nuts. Supplements are mainly helpful if you are deficient, so ask your doctor before starting one.
Can you take too much Selenium?
Yes. Selenium can be toxic in high amounts, causing symptoms like garlic-breath odor, hair and nail loss, nausea, and fatigue. Stay within recommended limits and avoid combining several Selenium-containing products.
Are Brazil nuts a good source of Selenium?
Brazil nuts are one of the richest natural sources, and even a couple can provide a large amount. Because of this, eating many daily plus taking a supplement could give you more than you need.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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