Drug & supplement interaction

Green Tea + Levothyroxine

Levothyroxine brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, and others.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Green Tea and Levothyroxine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the label for Levothyroxine states a food rule worth keeping to, and the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Green Tea and Levothyroxine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Levothyroxine and Green Tea in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Green Tea safety at a glance

Green Tea overall Use caution Drinking green tea is generally safe, but concentrated extracts in high doses have been linked to rare liver injury.

Pregnancy Possibly Safe When used orally in moderate amounts. Due to the caffeine content of green tea, pregnant patients should closely monitor their intake to ensure moderate consump... Read the full pregnancy detail

Breastfeeding Possibly Safe When used orally in moderate amounts. Due to the caffeine content of green tea, nursing parents should closely monitor caffeine intake. Breast milk concentratio... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Levothyroxine and Green Tea? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Levothyroxine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Levothyroxine is filed under 3 classifications — including thyroid hormone, oral drugs. Green Tea has documented interactions with 58 drug classes — the most serious being atorvastatin (lipitor) (major), ephedrine (major) and nadolol (corgard) (major) — and none of Levothyroxine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Green Tea Does Interact With Other Medications

Green Tea has 13 major, 905 moderate, 375 minor known drug interactions in our database — Levothyroxine isn’t one of them. If you take anything else, check it against the full list below.

Major 13 Moderate 905 Minor 375 No known interaction 1,537 (incl. Levothyroxine)

Taking anything else?

Check Another of Your Medications Against Green Tea

Covers the 2,830 medications we’ve checked against Green Tea. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Green Tea and Levothyroxine May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. 5 of them are worth acting on rather than waiting out — marked below.

Bone thinning Worth acting on Additional detail
Green Tea
“Orally, the ingestion of the green tea constituent epigallocatechin gallate (EGCG) or a decaffeinated green tea polyphenol mixture may cause mild muscle pain.

There is some concern regarding the association between caffeinated green tea products and osteoporosis. Epidemiological evidence regarding the relationship between caffeinated beverages such as green tea and the risk for osteoporosis is contradictory.”

Green Tea · Natural Medicines adverse-effect record, reported in bone loss.
5 sources cited

36398. Chow, H. H., Cai, Y., Hakim, I. A., Crowell, J. A., Shahi, F., Brooks, C. A., Dorr, R. T., Hara, Y., and Alberts, D. S. Pharmacokinetics and safety of green tea polyphenols after multiple-dose administration of epigallocatechin gallate and polyphenon E i

2669. Rapuri PB, Gallagher JC, Kinyamu HK, Ryschon KL. Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes. Am J Clin Nutr 2001;74:694-700. PubMed

10202. Massey LK. Is caffeine a risk factor for bone loss in the elderly? Am J Clin Nutr 2001;74:569-70. PubMed

11317. Massey LK, Whiting SJ. Caffeine, urinary calcium, calcium metabolism and bone. J Nutr 1993;123:1611-4. PubMed

6025. Lloyd T, Johnson-Rollings N, Eggli DF, et al. Bone status among postmenopausal women with different habitual caffeine intakes: a longitudinal investigation. J Am Coll Nutr 2000;19:256-61. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Seizures Worth acting on Additional detail
Green Tea
“Orally, green tea can cause central nervous system stimulation and adverse effects such as headache, anxiety, dizziness, insomnia, fatigue, agitation, tremors, restlessness, and confusion. These effects are more common with higher doses of green tea or green tea extract, equivalent to 5-6 liters of tea per day.”

Green Tea · Natural Medicines adverse-effect record, reported in anxiety.
6 sources cited

8117. Pisters KM, Newman RA, Coldman B, et al. Phase I trial of oral green tea extract in adult patients with solid tumors. J Clin Oncol 2001;19:1830-8. PubMed

11366. Jatoi A, Ellison N, Burch PA, et al. A phase II trial of green tea in the treatment of patients with androgen independent metastatic prostate carcinoma. Cancer 2003;97:1442-6.. PubMed

53719. Laurie, S. A., Miller, V. A., Grant, S. C., Kris, M. G., and Ng, K. K. Phase I study of green tea extract in patients with advanced lung cancer. Cancer Chemother.Pharmacol. 2005;55(1):33-38. PubMed

90139. Crew KD, Brown P, Greenlee H, Bevers TB, Arun B, Hudis C, McArthur HL, Chang J, Rimawi M, Vornik L, Cornelison TL, Wang A, Hibshoosh H, Ahmed A, Terry MB, Santella RM, Lippman SM, Hershman DL. Phase IB randomized, double-blinded, placebo-controlled, dose

102716. Filippini T, Malavolti M, Borrelli F, et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database Syst Rev. 2020;3(3):CD005004. PubMed

36398. Chow, H. H., Cai, Y., Hakim, I. A., Crowell, J. A., Shahi, F., Brooks, C. A., Dorr, R. T., Hara, Y., and Alberts, D. S. Pharmacokinetics and safety of green tea polyphenols after multiple-dose administration of epigallocatechin gallate and polyphenon E i
“Acute or short-term oral administration of green tea may cause hypertension. The risk may be greater for green tea products containing more than 200 mg epigallocatechin gallate (EGCG). However, consumption of brewed green tea does not seem to increase blood pressure or pulse, even in mildly hypertensive patients.”

Green Tea · Natural Medicines adverse-effect record, reported in arrhythmia.
6 sources cited

53719. Laurie, S. A., Miller, V. A., Grant, S. C., Kris, M. G., and Ng, K. K. Phase I study of green tea extract in patients with advanced lung cancer. Cancer Chemother.Pharmacol. 2005;55(1):33-38. PubMed

54014. Miller, R. J., Jackson, K. G., Dadd, T., Mayes, A. E., Brown, A. L., and Minihane, A. M. The impact of the catechol-O-methyltransferase genotype on the acute responsiveness of vascular reactivity to a green tea extract. Br.J.Nutr. 2011;105(8):1138-1144.

54065. Miller, R. J., Jackson, K. G., Dadd, T., Mayes, A. E., Brown, A. L., Lovegrove, J. A., and Minihane, A. M. The impact of the catechol-O-methyltransferase genotype on vascular function and blood pressure after acute green tea ingestion. Mol.Nutr.Food Res.

54076. Jurgens, T. M., Whelan, A. M., Killian, L., Doucette, S., Kirk, S., and Foy, E. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane.Database.Syst.Rev. 2012;12:CD008650. PubMed

102716. Filippini T, Malavolti M, Borrelli F, et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database Syst Rev. 2020;3(3):CD005004. PubMed

90161. Onakpoya I, Spencer E, Heneghan C, Thompson M. The effect of green tea on blood pressure and lipid profile: a systematic review and meta-analysis of randomized clinical trials. Nutr Metab Cardiovasc Dis. 2014 Aug;24:823-36. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
A severe allergic reaction / Hives Worth acting on Additional detail
Green Tea
“Orally, matcha tea has resulted in at least one case of anaphylaxis related to green tea proteins. A 9-year-old male experienced systemic redness and hives, nausea, and anaphylaxis 60 minutes after consuming matcha tea-flavored ice cream. The caffeine found in green tea can also cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare.”

Green Tea · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).
2 sources cited

107169. Kajita N, Miyama S, Kinoshita K, Yoshida K, Narita M. Green tea-induced anaphylaxis: The first pediatric case report. Allergol Int 2021;70(4):507-508. PubMed

11315. Infante S, Baeza ML, Calvo M, et al. Anaphylaxis due to caffeine. Allergy 2003;58:681-2. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
An allergic reaction Worth acting on Additional detail
Green Tea
“There is concern that some green tea products, especially green tea extracts, can cause hepatotoxicity in some patients. In 2017, the regulatory agency Health Canada re-issued a warning to consumers about this concern. The updated warning advises patients taking green tea extracts, especially those with liver disease, to watch for signs of liver toxicity.”

Green Tea · Natural Medicines adverse-effect record, reported in cholestasis.
6 sources cited

94897. Green Tea Extract-Containing Natural Health Products - Rare Risk of Serious Liver Injury. Recalls & alerts. November 15, 2017. http://healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2017/65100a-eng.php. Accessed November 10, 2017.

102722. Oketch-Rabah HA, Roe AL, Rider CV, et al. United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts. Toxicol Rep. 2020;7:386-402. PubMed

14136. Bonkovsky HL. Hepatotoxicity associated with supplements containing Chinese green tea (Camellia sinensis). Ann Intern Med 2006;144:68-71.

15026. Jimenez-Saenz M, Martinez-Sanchez, MDC. Acute hepatitis associated with the use of green tea infusions. J Hepatol 2006;44:616-9. PubMed

53740. Javaid, A. and Bonkovsky, H. L. Hepatotoxicity due to extracts of Chinese green tea (Camellia sinensis): a growing concern. J Hepatol 2006;45(2):334-335. PubMed

53746. Molinari, M., Watt, K. D., Kruszyna, T., Nelson, R., Walsh, M., Huang, W. Y., Nashan, B., and Peltekian, K. Acute liver failure induced by green tea extracts: case report and review of the literature. Liver Transpl. 2006;12(12):1892-1895. PubMed
“A case of granulomatous alveolitis with lymph follicles has been reported for a 67-year-old female who used green tea infusions to wash her nasal cavities for 15 years. Her symptoms disappeared 2 months after stopping this practice and following an undetermined course of corticosteroids. In a case report, hypersensitivity pneumonitis was associated with inhalation of catechin-rich green tea extracts.”

Green Tea · Natural Medicines adverse-effect record, reported in dental caries.
3 sources cited

54088. Sakamoto, O., Saita, N., Yamasaki, H., Tamanoi, M., and Ando, M. Pulmonary granulomatosis caused by aspirated green tea. Chest 1994;106(1):308-309. PubMed

54025. Otera, H., Tada, K., Sakurai, T., Hashimoto, K., and Ikeda, A. Hypersensitivity pneumonitis associated with inhalation of catechin-rich green tea extracts. Respiration 2011;82(4):388-392. PubMed

11365. Shirai T, Hayakawa H, Akiyama J, et al. Food allergy to green tea. J Allergy Clin Immunol 2003;112:805-6. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Weight loss Additional detail

Green Tea

Recorded for Green Tea in the same Natural Medicines adverse-effect record shown under Seizures above.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Mood changes or irritability Additional detail
Green Tea
“Green tea contains a significant amount of caffeine. Chronic use, especially in large amounts, can produce tolerance, habituation, and psychological dependence. The existence or clinical importance of caffeine withdrawal is controversial. Some researchers think that if it exists, it appears to be of little clinical significance. Other researchers suggest symptoms such as headache; tiredness and fatigue;”

Green Tea · Natural Medicines adverse-effect record, reported in anxiety.
4 sources cited

11832. Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: http://books.nap.edu/books/0309082587/html/index.html. DOI

11839. Dews PB, O'Brien CP, Bergman J. Caffeine: behavioral effects of withdrawal and related issues. Food Chem Toxicol 2002;40:1257-61. PubMed

13738. Juliano LM, Griffiths RR. A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology (Berl) 2004;176:1-29. PubMed

2723. Dews PB, Curtis GL, Hanford KJ, O'Brien CP. The frequency of caffeine withdrawal in a population-based survey and in a controlled, blinded pilot experiment. J Clin Pharmacol 1999;39:1221-32. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Sweating Additional detail

Green Tea

Recorded for Green Tea in the same Natural Medicines adverse-effect record shown under An allergic reaction above.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Anxiety or restlessness Additional detail

Green Tea

Recorded for Green Tea in the same Natural Medicines adverse-effect record shown under Seizures above.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Trouble sleeping Additional detail

Green Tea

Recorded for Green Tea in the same Natural Medicines adverse-effect record shown under Seizures above.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›

Showing the 10 most notable of 18 shared effects — ranked by how unusual each one is, not just whether both lists mention it.

Reported for Green Tea but not commonly for Levothyroxine: yellowing of the skin or eyes, trouble concentrating, dependence or withdrawal symptoms and liver problems.

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Green Tea come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Green Tea in Pregnancy & Breastfeeding

Pregnancy Possibly Safe

When used orally in moderate amounts. Due to the caffeine content of green tea, pregnant patients should closely monitor their intake to ensure moderate consumption. Fetal blood concentrations of caffeine approximate maternal concentrations. The use of caffeine during pregnancy is controversial; however, moderate consumption has not been associated with clinically important adverse fetal effects. In some studies consuming amounts over 200 mg daily is associated with a significantly increased risk of miscarriage. This increased risk may be most likely to occur in those with genotypes that confer a slow rate of caffeine metabolism. According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, most healthy pregnant patients can safely consume doses up to 300 mg daily without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations. Advise keeping caffeine consumption below 300 mg daily. This is similar to the amount of caffeine in about 6 cups of green tea. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as green tea, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product. Based on animal models, green tea extract catechins are also transferred to the fetus, but in amounts 50-100 times less than maternal concentrations. The potential impact of these catechins on the human fetus is not known, but animal models suggest that the catechins are not teratogenic.

Pregnancy Possibly Unsafe

When used orally in amounts providing more than 300 mg caffeine daily. Caffeine from green tea crosses the placenta, producing fetal blood concentrations similar to maternal levels. Consumption of caffeine in amounts over 300 mg daily is associated with a significantly increased risk of miscarriage in some studies. Advise keeping caffeine consumption from all sources below 300 mg daily. This is similar to the amount of caffeine in about 6 cups of green tea. High maternal doses of caffeine throughout pregnancy have also resulted in symptoms of caffeine withdrawal in newborn infants. High doses of caffeine have also been associated with spontaneous abortion, premature delivery, and low birth weight. However, some research has also found that intrauterine exposure to even modest amounts of caffeine, based on maternal blood levels during the first trimester, is associated with a shorter stature in children ages 4-8 years. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as green tea, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product. There is also concern that consuming large amounts of green tea might have antifolate activity and potentially increase the risk of folic acid deficiency-related birth defects. Catechins in green tea inhibit the enzyme dihydrofolate reductase in vitro. This enzyme is responsible for converting folic acid to its active form. Preliminary evidence suggests that increasing maternal green tea consumption is associated with increased risk of spina bifida. Also, evidence from epidemiological research suggests that serum folate levels in pregnant patients with high green tea intake (57.3 mL per 1000 kcal) are decreased compared to participants who consume moderate or low amounts of green tea. More evidence is needed to determine the safety of using green tea during pregnancy. For now, advise pregnant patients to avoid consuming large quantities of green tea.

Lactation Possibly Safe

When used orally in moderate amounts. Due to the caffeine content of green tea, nursing parents should closely monitor caffeine intake. Breast milk concentrations of caffeine are thought to be approximately 50% of maternal serum concentrations.

Lactation Possibly Unsafe

When used orally in large amounts. Consumption of green tea might cause irritability and increased bowel activity in nursing infants. There is insufficient reliable information available about the safety of green tea extracts when applied topically during breast-feeding.

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

How to take them

Some Levothyroxine Products Have a Food Rule — Green Tea Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Green Tea included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Levothyroxine on its own and move Green Tea to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Levothyroxine products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

Overlapping uses

What Levothyroxine Is Prescribed For, and What Green Tea Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Levothyroxine is a prescription medicine with approved uses on its FDA label. Green Tea is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Levothyroxine is prescribed for: Levothyroxine replaces or supplements the thyroid hormone your body isn't making enough of. It's used for hypothyroidism — an underactive thyroid — in adults, children, and even newborns, whether the cause is the thyroid gland itself, the pituitary gland, or the hypothalamus in the brain. It's also used alongside surgery and radioiodine treatment in people with certain types of thyroid cancer, to help suppress the hormone that can stimulate cancer growth. It is not meant for weight loss, treating benign thyroid nodules in people who have enough iodine, or for hypothyroidism during recovery from a temporary condition called subacute thyroiditis.

Green Tea has been studied for:

Depression studied, not established Green Tea has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

Green Tea for depression

It is unclear if drinking green tea is beneficial for depression prevention.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Levothyroxine on your own; if you are taking Green Tea for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Green Tea or Levothyroxine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Green Tea or Levothyroxine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Levothyroxine

This page covers Green Tea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levothyroxine page lists 50 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Tiratricol (major), Acetyl-l-carnitine (moderate), Alpha-lipoic Acid (moderate) and Ascophyllum Nodosum (moderate).

By severity: 2 major · 39 moderate · 9 minor.

From our pharmacist’s overview on the Levothyroxine page

“Levothyroxine replaces a hormone your body measures in tiny amounts, so small shifts in its blood level show up in how you feel, and I treat this list with genuine care. Nearly everything on it does one of two things: blocks the pill from being absorbed in the gut, the way everyday minerals like calcium do by binding it into complexes,…”

Reviewed by 2 · Jul 18, 2026

Open the Levothyroxine interaction page

One more smart check

Taking Green Tea as Part of a Dietary Supplement Product? Check It for Interactions

We hold 9,084 real supplement products containing Green Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Green Tea. Even though Green Tea itself has no known interaction with Levothyroxine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Green Tea and Levothyroxine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Green Tea

Top 5%

#26 of 1,452 supplements looked up here in the last 7 days

29 days ago today

Medication Levothyroxine

Top 10

#2 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?

Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Green Tea reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Green Tea and Levothyroxine records this page draws on were last updated July 11, 2026.
What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.

Data structure & sourcing designed and verified by Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Green Tea

What is Green Tea?

Antioxidant support
Weight loss
Heart health
Mental alertness
Cancer risk reduction

Green tea is a popular beverage rich in antioxidants called catechins, and drinking it in normal amounts is considered safe for most people. Concentrated green tea extracts are a different story—they may help modestly with weight or heart health for some, but high doses have been linked to rare liver problems. Talk to your pharmacist or doctor before taking green tea supplements, especially if you have liver concerns or are pregnant.

Camellia sinensis · Theaceae · Leaves and leaf buds · Brewed tea, capsules, tablets, standardized extracts, powders (matcha), and topical ointments

An interaction check asks whether these two react with each other — it does not ask whether Green Tea is a good idea for someone in your situation. Here is what our Green Tea record says about it on its own.

Green Tea: dosing

There is no single official dose for green tea. As a beverage, many people drink a few cups per day without problems. For supplements, the right amount depends on the product and how concentrated it is.Because extracts vary widely in strength, it is best to follow the directions on the product label and not exceed the recommended dose. They can help you decide if it is appropriate and what amount is reasonable.

From our Green Tea monograph — the full record covers uses, side effects and every documented interaction.

Read the full Green Tea monograph & all interactions

Medication

About Levothyroxine

What Is Levothyroxine Used For?

Brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, Levo-T, Eltroxin, Estre, Levothyroxine, Novothyrox, Levolet

Levothyroxine replaces or supplements the thyroid hormone your body isn't making enough of. It's used for hypothyroidism — an underactive thyroid — in adults, children, and even newborns, whether the cause is the thyroid gland itself, the pituitary gland, or the hypothalamus in the brain.

It's also used alongside surgery and radioiodine treatment in people with certain types of thyroid cancer, to help suppress the hormone that can stimulate cancer growth. It is not meant for weight loss, treating benign thyroid nodules in people who have enough iodine, or for hypothyroidism during recovery from a temporary condition called subacute thyroiditis.

See full Levothyroxine drug information

Keep checking

Other Drugs & Green Tea

Browse every other medication we’ve checked against Green Tea — both the ones with a known interaction and the ones without. Select any drug for the full detail.

13Major

905Moderate

375Minor

1,536No known interaction

13 Major 905 Moderate 375 Minor 1,536 No interaction

Major

13 interactions

Moderate

905 interactions

Showing 60 of 905 moderate interactions — see all 905 on the Green Tea page.

Minor

375 interactions

Showing 60 of 375 minor interactions — see all 375 on the Green Tea page.

No interaction 1,536 drugs checked — show the list

We also checked Green Tea against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,536 medications checked with no known interaction — see the full Green Tea list.

See the full Green Tea interactions page

See every supplement checked against Levothyroxine, ranked by severity

Evidence & sources

Green Tea References

The 219 references that drive our Green Tea 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.

McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
Harder S, Fuhr U, Staib AH, Wolff T. Ciprofloxacin-caffeine: a drug interaction established using in vivo and in vitro investigations. Am J Med 1989;87:89S-91S. PubMed
Carbo M, Segura J, De la Torre R, et al. Effect of quinolones on caffeine disposition. Clin Pharmacol Ther 1989;45:234-40. PubMed
Healy DP, Polk RE, Kanawati L, et al. Interaction between oral ciprofloxacin and caffeine in normal volunteers. Antimicrob Agents Chemother 1989;33:474-8. PubMed
Mester R, Toren P, Mizrachi I, et al. Caffeine withdrawal increases lithium blood levels. Biol Psychiatry 1995;37:348-50. PubMed
Jefferson JW. Lithium tremor and caffeine intake: two cases of drinking less and shaking more. J Clin Psychiatry 1988;49:72-3.
Mitscher LA, Mitscher LA, Jung M, Shankel D, et al. Chemoprotection: a review of the potential therapeutic antioxidant properties of green tea (Camellia sinensis) and certain of its constituents. Med Res Rev 1997;17:327-65.
Joeres R, Klinker H, Heusler H, et al. Influence of mexiletine on caffeine elimination. Pharmacol Ther 1987;33:163-9. PubMed
Vahedi K, Domingo V, Amarenco P, Bousser MG. Ischemic stroke in a sportsman who consumed MaHuang extract and creatine monohydrate for bodybuilding. J Neurol Neurosurg Psychiatr 2000;68:112-3.
Wakabayashi K, Kono S, Shinchi K, et al. Habitual coffee consumption and blood pressure: A study of self-defense officials in Japan. Eur J Epidemiol 1998;14:669-73. PubMed
Hodgson JM, Puddey IB, Burke V, et al. Effects on blood pressure of drinking green and black tea. J Hypertens 1999;17:457-63. PubMed
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Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Green Tea and Levothyroxine Together: Common Questions

Is it safe to take Green Tea with Levothyroxine?

We do not list a known interaction between Green Tea and Levothyroxine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.

Do Green Tea and Levothyroxine have any of the same side effects?

Yes — our sources link each of them separately to 10 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.

Should I take Green Tea and Levothyroxine at the same time of day?

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Levothyroxine on its own and move Green Tea to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.

Are Green Tea and Levothyroxine used for the same thing?

They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Green Tea in each. That is a conversation for your prescriber, especially if Levothyroxine is being adjusted to a target.

How was the Green Tea and Levothyroxine combination checked?

Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Green Tea has documented interactions with 58 drug classes — none of Levothyroxine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.

Does Green Tea interact with any other medications?

Yes. Green Tea has 1,293 documented drug interactions in our database — Levothyroxine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

Does Levothyroxine interact with any supplements?

Yes. Levothyroxine has documented interactions with 50 supplements in our database — Green Tea is not one of them. The Levothyroxine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Green Tea monograph Uses, safety profile, and every drug interaction in one place Levothyroxine drug information The full plain-English guide to this medication Levothyroxine supplement interactions Every supplement checked against Levothyroxine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 219 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine and Green Tea?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.

case report: A written account of what happened to one patient, useful as a signal but not proof of cause.

Absorption: How a medicine moves from where it is taken, such as the stomach or gut, into the bloodstream.

agitation: A state of feeling restless and upset and being unable to relax, sometimes with pacing or fidgeting.

anaphylaxis: A sudden, severe, whole-body allergic reaction that can cause trouble breathing, swelling, and a drop in blood pressure, needing emergency care.

anxiety: A feeling of worry, nervousness, or unease, sometimes along with a racing heart or restlessness.

Drug Interactions: The label section listing other medicines, foods, or substances that can change how a medicine works or raise the chance of side effects.

hepatotoxicity: Damage to the liver caused by a medicine or other substance.

hypersensitivity: An overreaction of the body's defense system to a substance, causing symptoms such as rash, swelling, or trouble breathing.

hypertension: Blood pressure that stays higher than normal, commonly called high blood pressure.

inhalation: Breathed in through the mouth or nose so the medicine reaches the lungs or airways.

insomnia: Trouble falling asleep, staying asleep, or getting restful sleep.

osteoporosis: A condition where bones become thin and weak, making them more likely to break.

pneumonitis: Inflammation of the lung tissue that is not caused by an infection and can lead to cough and breathlessness.

restlessness: An inability to stay calm or still, with a constant feeling of needing to move.

tolerance: When the body gets used to a medicine over time, so a larger dose is needed to get the same effect.

withdrawal: Uncomfortable physical or mental symptoms that appear when a medicine the body has gotten used to is reduced or stopped.