Interactions on record — worth a quick check against your medications. Check your meds →
Dietary supplement

Day Ingredients & Drug Interactions

by Natrol

Day label
See full label image
Tablet Or Pill Category: Other Combinations
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Day against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Day is a dietary supplement by Natrol with 5 active ingredients. Its ingredients are commonly taken for morning sickness in pregnancy, premenstrual syndrome (pms), preventing or treating b6 deficiency.Based on those ingredients, 599 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are L-Theanine, 5-HTP, Vitamin B6. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Day by Natrol

Ask about any prescription or over-the-counter medication and we check it for interactions with Day by Natrol — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Day by Natrol

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 23, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 5 of its 5 active ingredients.
  • “Folate” is listed as a grouped ingredient — the label gives one combined amount (333 mcg DFE) without saying how much of each component you get.

Natrol Day contains five active ingredients: vitamin B6, folic acid, vitamin B12, 5-HTP, and L-theanine. Vitamin B6 supports nerve function and is used to treat deficiency and certain types of anemia.

Folic acid is essential for cell division and birth defect prevention in pregnancy. Vitamin B12 is needed for nerve health and red blood cell formation.

5-HTP is a precursor to serotonin, a brain chemical involved in mood. L-theanine is an amino acid that may support calm focus.

The tablet also contains inactive ingredients including calcium phosphate, cellulose, stearic acid, and silica as fillers and binders.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: calm and relaxation during the day.
  • We looked for evidence on: Anxiety, Depression, stress, mood support.
  • The strongest evidence on file: 5-htp is rated "Possibly Effective" for Depression (Natural Medicines).
  • Also on file: Folic Acid is rated "Possibly Effective" for Depression.
  • Also on file: 5-htp is rated "Insufficient Reliable Evidence To Rate" for Anxiety.

Vitamin B6 is effective for sideroblastic anemia and B6 deficiency, and likely effective for high homocysteine levels. It's possibly effective for pregnancy-related nausea.

Folic acid is effective for folate deficiency, likely effective for preventing neural tube birth defects and reducing methotrexate side effects, and possibly effective for depression and gum overgrowth from phenytoin. Vitamin B12 is effective for B12 deficiency and certain genetic conditions, likely effective for cyanide poisoning, and possibly effective for canker sores and nerve pain after shingles.

5-HTP is possibly effective for depression but possibly ineffective for Down syndrome; evidence is insufficient for Alzheimer's disease, panic disorder, and cerebellar ataxia. L-theanine is possibly effective for cognitive function, but evidence is insufficient for age-related cognitive decline, Alzheimer's disease, generalized anxiety, obsessive-compulsive disorder, and cancer.

The evidence, ingredient by ingredient Vitamin B6 Vitamin B12 Folic Acid 5-htp Theanine

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 5 of the 5 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 5 of 5.
  • General safety write-ups exist for 5 of 5.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Vitamin B6 is generally well-tolerated at standard doses but can damage nerves (sensory neuropathy) at high doses, especially over 1,000 mg daily or cumulative totals of 1,000 grams or more. Common side effects include abdominal pain, nausea, and headache.

It's likely safe in pregnancy and lactation at normal amounts, though high doses should be avoided without medical guidance. Folic acid is generally well-tolerated at recommended doses; at 5 mg daily, some people report abdominal cramps and diarrhea, and at 15 mg daily, confusion and sleep disturbances can occur.

Use in late pregnancy has been associated with increased asthma risk in children in some studies. It's likely safe during pregnancy and lactation at standard prenatal doses.

Vitamin B12 is very well-tolerated with no established upper limit; excess is removed in the urine and it's safe at recommended doses in pregnancy and lactation. 5-HTP is generally tolerated short-term but causes drowsiness, nausea, diarrhea, and abdominal pain in a small number of people; rare serious effects include mania and hallucinations.

It should be avoided during pregnancy and breastfeeding due to insufficient safety data. L-theanine may cause headaches and drowsiness; long-term safety is not well studied.

It should be avoided in pregnancy and lactation due to lack of safety data.

Side effects, ingredient by ingredient Vitamin B6 Vitamin B12 Folic Acid 5-htp Theanine

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 5 of the 5 matched ingredients can interact with medications — 5-htp, Vitamin B12, Vitamin B6, Folic Acid, Theanine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: Parkinson's medications.
  • For scale: 599 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking this product, check with your doctor or pharmacist if you take seizure medications (phenobarbital, phenytoin, primidone), blood pressure medications, carbidopa (for Parkinson's), cancer medications (capecitabine, 5-fluorouracil, pyrimethamine, methotrexate), serotonergic antidepressants, CNS depressants (sedatives), amiodarone (Cordarone), metformin (Glucophage), or levodopa. The most serious interactions are with seizure medications, where high-dose B6 or folic acid can reduce their blood levels and effectiveness.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

Natrol Day may be worth considering if you're looking to support B-vitamin intake, mood, and calm focus—but it has significant interactions with seizure medications, blood pressure drugs, cancer treatments, and serotonergic antidepressants. If you take any prescription medication, especially for seizures, heart rhythm, blood pressure, diabetes, or mood, talk with your doctor or pharmacist before starting this product.

Pregnant or breastfeeding women should check with their provider, particularly about 5-HTP and L-theanine.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 5 of 5 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated May 28, 2019.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Day, straight from the product label.

Brand Natrol
Net contents 2 Blister Pack(s)
Market status On market
Date entered into DSLD May 28, 2019
DSLD ID 203169
Product type Other Combinations
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegetarian, Adult (18 - 50 Years), Dairy Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Day by Natrol, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Tablet(s)
Maximum serving Sizes:
1 Tablet(s)
Servings per container
30
IngredientAmount% DV
Vitamin B610 mg590%
Folic Acid200 mcg--
Vitamin B1250 mcg2080%
Folate333 mcg DFE80%
5-HTP50 mg--
L-Theanine50 mg--

Other ingredients: Dibasic Calcium Phosphate, Microcrystalline Cellulose, Stearic Acid, Hypromellose, Silicon Dioxide, Magnesium Stearate, Cellulose Gum, Methylcellulose, Glycerin

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Directions: Take 1 white tablet, one or two times daily, with food. Do not exceed recommended dose.

Precautions

Do not exceed recommended dose.

Keep out of reach of children.

Warning: Consult your healthcare professional prior to use if you have or suspect a medical condition, or are taking prescription drugs, including drugs for depression, migraines, Parkinson's disease or psychiatric disorders. Do not use with other supplements containing L-Tryptophan or 5-HTP. Do not use if you are pregnant, lactating or under the age of 18 years.

Do not use if you are pregnant, lactating or under the age of 18 years.

Tamper evident packaging. Tablets are sealed in blisters.

Formulation

No: Milk, egg, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans, yeast, artificial colors or flavors, added sugar or preservatives

100% drug-free

Vegetarian

Storage

Store in a cool, dry place.

Formula

Natrol Stress & Anxiety consists of two separate blends to meet your daytime vs. nighttime needs. The daytime promotes calm and relaxation during the day: 5-HTP supports serotonin which helps enhance moods. Vitamin B-6, B-12 and Folic Acid help maintain emotional well-being. L-Theanine ensures relaxation without making you drowsy

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.

General Statements

Mood & stress Day Promotes calm & relaxation Helps reduce occasional anxiety

Value size Two 30 tablet blister packs (60 total)

Seals/Symbols

Vegetarian

FDA Statement of Identity

Dietary Supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Day by Natrol label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Day label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Day by Natrol

These are the 5 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Tablet(s) Dosage formTablet Or Pill Servings per container30 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Vitamin B6

Interacts with
210 drugs
10 mg per serving Form: Pyridoxine Hydrochloride

Vitamin B6 (pyridoxine) is an essential water-soluble vitamin that your body needs for metabolism, brain function, and making red blood cells. It is b...

Vitamin B6 monograph & interactions

Vitamin B12

Interacts with
20 drugs
50 mcg per serving Form: Cyanocobalamin

Vitamin B12 (cobalamin) is an essential nutrient your body needs to make red blood cells, keep nerves healthy, and support DNA. Supplements are very h...

Vitamin B12 monograph & interactions

Folate

333 mcg DFE per serving

5-HTP

Interacts with
398 drugs
50 mg per serving Form: Griffonia simplicifolia

5-HTP is a compound your body uses to make serotonin, and people take it as a supplement hoping to improve mood, sleep, and headaches. Some early rese...

5-HTP monograph & interactions

L-Theanine

Interacts with
565 drugs
50 mg per serving

Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong dro...

L-Theanine monograph & interactions

Other (inactive) ingredients: Dibasic Calcium Phosphate, Microcrystalline Cellulose, Stearic Acid, Hypromellose, Silicon Dioxide, Magnesium Stearate, Cellulose Gum, Methylcellulose, Glycerin. These complete the product’s ingredient list but are not active constituents.

Interaction report

Day by Natrol Drug Interactions

Want to check YOUR meds against Day?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
599Drugs
577 Moderate 22 Minor

Ingredients driving the most interactions

L-Theanine 565
5-HTP 398
Vitamin B6 210
Folic Acid 40
Vitamin B12 20

Individual Drug Interactions

The ingredients in Day interact with 599 drugs. Click any drug to see the details.

5 of the 5 ingredients in Day interact with drugs. Each result below shows which ingredient is responsible. L-Theanine 5-HTP Vitamin B6 Folic Acid Vitamin B12

Each ingredient & the kinds of drugs it affects

For each ingredient in Day with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

L-Theanine3 drug types · 565 drugs

Antihypertensive Drugs

Theanine might lower blood pressure, potentiating the effects of antihypertensive drugs.
Animal research shows that theanine can lower blood pressure in spontaneously hypertensive animals. Theoretically, concomitant use of theanine and antihypertensive drugs might potentiate the antihypertensive activity.

Likelihood Possible Evidence D
Cns Depressants

Theoretically, theanine might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.
Theoretically, theanine may compete with glutamate and/or increase plasma gamma-aminobutyric acid (GABA) levels, which could cause CNS depression. In one clinical study, some subjects taking oral theanine reported drowsiness.

Likelihood Unlikely Evidence D
Serotonergic Drugs

Clinical studies regarding the effects of L-theanine on serotonin levels are conflicting. Some studies suggest it can increase serotonin levels in the brain while others report that it may decrease them. Nevertheless, there have been no reports of l-theanine being a causative agent in serotonergic-related side effects or serotonin syndrome.

Likelihood Unlikely Evidence C
L-Theanine full monograph & interactions

5-HTP3 drug types · 398 drugs

Carbidopa (Lodosyn)

Combining 5-HTP and carbidopa can increase the risk of serotonergic side effects.
Carbidopa is sometimes used with 5-HTP to minimize peripheral 5-HTP metabolism and boost the amount that reaches the brain. However, this combination might also increase the risk of some side effects including hypomania, restlessness, rapid speech, anxiety, insomnia, and aggressiveness. Combining carbidopa and 5-HTP might also increase the risk of scleroderma-like skin changes due to elevated serotonin levels.

Likelihood Possible Evidence D
Cns Depressants

Theoretically, concomitant use of 5-HTP with medications that cause sedation might have additive effects.
In clinical trials, 5-HTP has been associated with drowsiness and somnolence.

Likelihood Possible Evidence D
Serotonergic Drugs

Combining serotonergic drugs with 5-HTP might cause additive serotonergic effects.
5-HTP can increase serotonin levels and cause serotonergic effects. Theoretically, combining serotonergic drugs with 5-HTP might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders. However, serotonin syndrome with 5-HTP has not yet been reported in humans. Monitor patients for signs of serotonin syndrome and other serotonergic side effects if using 5-HTP with serotonergic drugs.

Likelihood Possible Evidence D
5-HTP full monograph & interactions

Vitamin B65 drug types · 210 drugs

Amiodarone (Cordarone)

Theoretically, vitamin B6 might increase the photosensitivity caused by amiodarone.
Despite initial case reports suggesting that pyridoxine may have a protective effect against amiodarone-induced photosensitivity, preliminary clinical research suggests that pyridoxine may actually exacerbate this adverse effect.

Likelihood Possible Evidence B
Antihypertensive Drugs

Theoretically, vitamin B6 may have additive effects when used with antihypertensive drugs.
Research in hypertensive rats shows that vitamin B6 can decrease systolic blood pressure. Similarly, clinical research in patients with hypertension shows that taking high doses of vitamin B6 may reduce systolic and diastolic blood pressure, possibly by reducing plasma levels of epinephrine and norepinephrine.

Likelihood Possible Evidence B
Phenobarbital (Luminal)

High doses of vitamin B6 may reduce the levels and clinical effects of phenobarbital.
Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenobarbital, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenobarbital to avoid high doses of vitamin B6.

Likelihood Possible Evidence D
Phenytoin (Dilantin)

High doses of vitamin B6 may reduce the levels and clinical effects of phenytoin.
Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenytoin, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenytoin to avoid high doses of vitamin B6.

Likelihood Possible Evidence D
Levodopa

Vitamin B6 may increase the metabolism of levodopa when taken alone, but not when taken in conjunction with carbidopa.
Vitamin B6 (pyridoxine) enhances the metabolism of levodopa, reducing its clinical effects. However, this interaction does not occur when carbidopa is used concurrently with levodopa (Sinemet). Therefore, it is not likely to be a problem in most people.

Likelihood Unlikely Evidence D
Vitamin B6 full monograph & interactions

Folic Acid7 drug types · 40 drugs

5-Fluorouracil

Theoretically, high doses of folic acid might increase the toxicity of 5-fluorouracil.
Increases in gastrointestinal side effects of 5-fluorouracil, such as stomatitis and diarrhea, have been described in two clinical studies when leucovorin, a form of folic acid, was administered with 5-fluorouracil.

Likelihood Possible Evidence D
Capecitabine (Xeloda)

Use of high-dose folic acid might contribute to capecitabine toxicity.
Clinical research suggests that higher serum folate levels are associated with an increased risk for moderate or severe toxicity during capecitabine-based treatment for colorectal cancer. Additionally, in one case report, taking folic acid 15 mg daily might have contributed to increased toxicity, including severe diarrhea, vomiting, edema, hand-foot syndrome, and eventually death, in a patient prescribed capecitabine.

Likelihood Possible Evidence D
Methotrexate (Trexall, Others)

Folic acid might reduce the efficacy of methotrexate as a cancer treatment when given concurrently.
Methotrexate exerts its cytotoxic effects by preventing conversion of folic acid to the active form needed by cells. There is some evidence that folic acid supplements reduce the efficacy of methotrexate in the treatment of acute lymphoblastic leukemia, and theoretically they could reduce its efficacy in the treatment of other cancers. Advise cancer patients to consult their oncologist before using folic acid supplements. In patients treated with long-term, low-dose methotrexate for rheumatoid arthritis (RA) or psoriasis, folic acid supplements can reduce the incidence of side effects, without reducing efficacy.

Likelihood Probable Evidence B
Phenobarbital (Luminal)

Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Folic acid can have direct convulsant activity in some people, reversing the effects of phenobarbital and worsening seizure control. Monitor closely for increased seizure activity.

Likelihood Probable Evidence B
Phenytoin (Dilantin)

Folic acid might reduce serum levels of phenytoin in some patients.
Folic acid may be a cofactor in phenytoin metabolism. Folic acid, in doses of 1 mg daily or more, can reduce serum levels of phenytoin in some patients. Increases in seizure frequency have been reported. If folic acid supplements are added to established phenytoin therapy, monitor serum phenytoin levels closely. If phenytoin and folic acid are started at the same time and continued together, adverse changes in phenytoin pharmacokinetics are avoided. Note that phenytoin also reduces serum folate levels.

Likelihood Probable Evidence B
Primidone (Mysoline)

Folic acid might have antagonistic effects on primidone and increase the risk for seizures.
Folic acid can have direct convulsant activity in some people, reversing the effects of primidone and worsening seizure control. Monitor closely for increased seizure activity. Note that primidone also reduces serum folate levels.

Likelihood Probable Evidence B
Pyrimethamine (Daraprim)

Folic acid might antagonize the effects of pyrimethamine.
Folic acid can antagonize the antiparasitic effects of pyrimethamine against toxoplasmosis and Pneumocystis carinii pneumonia. Folic acid doesn't antagonize the effects of pyrimethamine in the treatment of malaria, because malarial parasites cannot use exogenous folic acid. Use folinic acid as an alternative to folic acid when indicated.

Likelihood Probable Evidence D
Folic Acid full monograph & interactions

Vitamin B121 drug type · 20 drugs

Metformin (Glucophage)

Metformin, a common medication used to manage type 2 diabetes, has been associated with lower vitamin B12 levels in some individuals. Prolonged use of metformin can interfere with the absorption of B12 in the digestive system, potentially leading to a deficiency in this essential vitamin.

Likelihood Possible Evidence A
Vitamin B12 full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Day, from the product label.

Natrol

See all Natrol products
Name
Natrol LLC
City
Chatsworth
State
CA
ZipCode
91311
Phone Number
1-800-262-8765
Web Address
www.natrol.com
Pharmacist Counseling Corner

Day by Natrol: Common Questions

Does Day by Natrol interact with any medications?
Yes. Based on its ingredients, Day has a known interaction with 599 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Day contains 5 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Is Natrol Day safe to take in pregnancy?
The ingredients have mixed pregnancy safety ratings. Vitamin B6 and folic acid are generally safe at recommended prenatal doses, but B6 should not be taken in high doses. 5-HTP and L-theanine should be avoided in pregnancy due to insufficient safety data. Talk with your doctor or pharmacist before taking this product if you're pregnant, as they can advise on whether each ingredient is right for you.
Can I take this while breastfeeding?
Vitamin B6, folic acid, and vitamin B12 are considered safe at recommended levels while breastfeeding. 5-HTP and L-theanine lack sufficient safety data, so they should be avoided during breastfeeding. Speak with your doctor or pharmacist to confirm this product is appropriate for you.
What is 5-HTP and what does it do?
5-HTP is an amino acid your body makes from the dietary amino acid tryptophan. It's a precursor to serotonin, a brain chemical involved in mood and sleep. The supplement is possibly effective for depression, but it carries interactions with antidepressants and sedating medications and can cause drowsiness, nausea, and mood changes.
What is L-theanine and is it calming?
L-theanine is an amino acid found naturally in green tea. It's possibly effective for supporting cognitive function, but evidence for anxiety or other conditions is insufficient in the data we hold. It may cause drowsiness in some people and can theoretically lower blood pressure, so talk with your provider if you take blood pressure medications.
Can high doses of vitamin B6 in this product cause nerve damage?
Nerve damage from B6 (sensory neuropathy) typically occurs with high daily doses over 1,000 mg or cumulative lifetime doses of 1,000 grams or more. A single daily tablet of Natrol Day is unlikely to deliver that level unless you're taking very high-dose supplements in addition, but prolonged use of multiple B6 supplements warrants discussion with your pharmacist.
Why should I avoid this if I take seizure medication?
Both vitamin B6 and folic acid can interfere with seizure medications like phenobarbital and phenytoin by speeding up how your body breaks them down, which may lower blood levels and reduce their effectiveness in controlling seizures. If you take seizure medication, check with your doctor before adding this product.

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

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Day label
Go deeper

The Full Monographs Behind Day’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Vitamin B6

Interacts with 210 drugs

Vitamin B6 (pyridoxine) is an essential water-soluble vitamin that your body needs for metabolism, brain function, and making red blood cells. It is best known for helping with pregnancy-rel...

Read the full Vitamin B6 monograph → Herb & supplement monograph

Vitamin B12

Interacts with 20 drugs

Vitamin B12 (cobalamin) is an essential nutrient your body needs to make red blood cells, keep nerves healthy, and support DNA. Supplements are very helpful for people who are deficient — su...

Read the full Vitamin B12 monograph → Herb & supplement monograph

Folic Acid

Interacts with 40 drugs

Folic acid is the man-made form of vitamin B9 and is one of the most well-studied supplements, especially for preventing serious birth defects when taken before and during early pregnancy. I...

Read the full Folic Acid monograph → Herb & supplement monograph

5-htp

Interacts with 398 drugs

5-HTP is a compound your body uses to make serotonin, and people take it as a supplement hoping to improve mood, sleep, and headaches. Some early research is promising, but the overall evide...

Read the full 5-htp monograph → Herb & supplement monograph

Theanine

Interacts with 565 drugs

Theanine (usually L-theanine) is an amino acid found naturally in tea leaves that many people take to feel calmer and less stressed without strong drowsiness. Early research suggests it may...

Read the full Theanine monograph →
Sources

Sources & How We Checked

Day's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 156 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Vitamin B6 32 references
  1. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  2. Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: The new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706. PubMed
  3. Geerling BJ, Dagnelie PC, Badart-Smook A, et al. Diet as a risk factor for the development of ulcerative colitis. Am J Gastroenterol 2000;95:1008-13. PubMed
  4. South M. Neonatal seizures after pyridoxine use -- reply. Lancet 1999;354:2083. PubMed
  5. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (2000). Washington, DC: National Academy Press, 2000. Available at: http://b
  6. Baxter P, Aicardi J. Neonatal seizures after pyridoxine use. Lancet 1999;354:2082-3. PubMed
  7. Bendich A, Cohen M. Vitamin B6 safety issues. Ann N Y Acad Sci 1990;585:321-30.
  8. Schaumburg H, Kaplan J, Windebank A. Sensory neuropathy from pyridoxine abuse. A new megavitamin syndrome. N Engl J Med 1983;309:445-8. PubMed
  9. Gordon N. Pyridoxine dependency: an update. Dev Med Child Neurol 1997;39:63-5. PubMed
  10. Lewis PJ. Pain in the hand and wrist. Pyridoxine supplements may help patients with carpal tunnel syndrome. BMJ 1995;310:1534. PubMed
  11. Kaufman G. Pyridoxine against amiodarone-induced photosensitivity (letter). Lancet 1984;1:51-2. PubMed
  12. Mulrow JP, Mulrow CD, McKenna WJ. Pyridoxine and amiodarone-induced photosensitivity. Ann Intern Med 1985;103:68-9. PubMed
  13. Kawada A, Kashima A, Shiraishi H, et al. Pyridoxine-induced photosensitivity and hypophosphatasia. Dermatology 2000;201:356-60.. PubMed
  14. Vasile A, Goldberg R, Kornberg B. Pyridoxine toxicity: report of a case. J Am Osteopath Assoc 1984;83:790-1. DOI
  15. Hansson O, Sillanpaa M. Pyridoxine and serum concentration of phenytoin and phenobarbitone. Lancet 1976;1:256. DOI
  16. Jansen T, Romiti R, Kreuter A, Altmeyer P. Rosacea fulminans triggered by high-dose vitamins B6 and B12. J Eur Acad Dermatol Venereol 2001;15:484-5..
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See these in context on the 5-htp monograph →

Theanine 6 references
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  2. Haskell, C. F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., and Scholey, A. B. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol.Psychol. 2008;77(2):113-122. PubMed
  3. Yokogoshi, H., Kato, Y., Sagesaka, Y. M., Takihara-Matsuura, T., Kakuda, T., and Takeuchi, N. Reduction effect of theanine on blood pressure and brain 5-hydroxyindoles in spontaneously hypertensive rats. Biosci.Biotechnol.Biochem. 1995;59(4):615-618. PubMed
  4. Lyon MR, Kapoor MP, Juneja LR. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev. 2011;16(4):348-
  5. Hidese S, Ota M, Wakabayashi C, et al. Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. Acta Neuropsychiatr 2017;29(2):72-9.
  6. Tsuchiya T, Honda H, Oikawa M, et al. Oral administration of the amino acids cystine and theanine attenuates the adverse events of S-1 adjuvant chemotherapy in gastrointestinal cancer patients. Int J Clin Oncol 2016;21(6):1085-90. PubMed

See these in context on the Theanine monograph →

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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.

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