Drug & supplement interaction

Oolong 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 Oolong 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

Oolong 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 Oolong 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.

Oolong Tea safety at a glance

Oolong Tea overall Generally safe Generally safe for most healthy adults when consumed as a beverage in moderate amounts.

Pregnancy Possibly Safe When used orally in moderate amounts. Due to the caffeine content of oolong tea, mothers should closely monitor their intake to ensure moderate consumption. Fet... Read the full pregnancy detail

Breastfeeding Possibly Safe When used orally in moderate amounts. Due to the caffeine content of oolong tea, caffeine intake should be closely monitored. Breast milk concentrations of caff... 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 Oolong 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. Oolong Tea has documented interactions with 37 drug classes — the most serious being ephedrine (major), adenosine (adenocard) (moderate) and anticoagulant/antiplatelet drugs (moderate) — 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

Oolong Tea Does Interact With Other Medications

Oolong Tea has 8 major, 518 moderate, 126 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 8 Moderate 518 Minor 126 No known interaction 2,178 (incl. Levothyroxine)

Taking anything else?

Check Another of Your Medications Against Oolong Tea

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

What to actually watch for

No Interaction Found — But Data Suggests Oolong 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. 4 of them are worth acting on rather than waiting out — marked below.

Bone thinning Worth acting on Additional detail
Oolong Tea
“Oolong tea contains caffeine. Some epidemiological research has found that caffeine may be associated with an increased risk of osteoporosis, but conflicting evidence exists. Caffeine can increase urinary excretion of calcium. Women identified with a genetic variant of the vitamin D receptor appear to be at an increased risk for the detrimental effect of caffeine on bone mass.”

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

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

98806. Wikoff D, Welsh BT, Henderson R, et al. Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children. Food Chem Toxicol 2017;109:585-648. 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 ›
Seizures Worth acting on Additional detail
Oolong Tea
“Oolong tea contains caffeine. Orally, caffeine can cause insomnia, nervousness, headache, anxiety, agitation, jitteriness, restlessness, ringing in the ears, tremors, delirium, and convulsions. Caffeine may also exacerbate sleep disturbances in patients with acquired immunodeficiency syndrome (AIDS).

There is some concern that stopping regular use of caffeine may cause withdrawal symptoms such as headache, tiredness…”

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

10755. Schechter MD, Timmons GD. Objectively measured hyperactivity--II. Caffeine and amphetamine effects. J Clin Pharmacol 1985;25:276-80.. PubMed

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

11838. Holmgren P, Norden-Pettersson L, Ahlner J. Caffeine fatalities--four case reports. Forensic Sci Int 2004;139:71-3. PubMed

13735. Leson CL, McGuigan MA, Bryson SM. Caffeine overdose in an adolescent male. J Toxicol Clin Toxicol 1988;26:407-15. PubMed

10204. Dreher HM. The effect of caffeine reduction on sleep quality and well-being in persons with HIV. J Psychosom Res 2003;54:191-8.. 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
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Chest pain Worth acting on Additional detail
Oolong Tea
“Orally, oolong tea can cause some cardiovascular-related adverse effects. Some of these effects may be due to the caffeine content of oolong tea. Acute oral administration of caffeine can cause increased blood pressure, but regular consumption does not seem to increase either blood pressure or pulse, even in mildly hypertensive patients.”

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

1451. 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

1452. 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

2722. Nurminen ML, Niittynen L, Korpela R, Vapaatalo H. Coffee, caffeine and blood pressure: a critical review. Eur J Clin Nutr 1999;53:831-9. PubMed

13739. Winkelmayer WC, Stampfer MJ, Willett WC, Curhan GC. Habitual caffeine intake and the risk of hypertension in women. JAMA 2005;294:2330-5. PubMed

38018. Conen, D., Chiuve, S. E., Everett, B. M., Zhang, S. M., Buring, J. E., and Albert, C. M. Caffeine consumption and incident atrial fibrillation in women. Am J Clin Nutr 2010;92(3):509-514. PubMed

38076. Gronroos, N. N. and Alonso, A. Diet and risk of atrial fibrillation - epidemiologic and clinical evidence -. Circ.J 2010;74(10):2029-2038. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
A severe allergic reaction Worth acting on Additional detail
Oolong Tea
“Oolong tea contains caffeine. Caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare.”

Oolong Tea · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).
1 source cited

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 ›
Mood changes or irritability / Tiredness / Headache Additional detail

Oolong Tea

Recorded for Oolong 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 ›
A fast or pounding heartbeat Additional detail

Oolong Tea

Recorded for Oolong 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 ›
Anxiety or restlessness / Trouble sleeping Additional detail

Oolong Tea

Recorded for Oolong 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 ›

Reported for Oolong Tea but not commonly for Levothyroxine: trouble concentrating, raised blood pressure, fainting and dependence or withdrawal symptoms.

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Oolong 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

Oolong Tea in Pregnancy & Breastfeeding

Pregnancy Possibly Safe

When used orally in moderate amounts. Due to the caffeine content of oolong tea, mothers should closely monitor their intake to ensure moderate consumption. Fetal blood concentrations of caffeine approximate maternal concentrations. Use of caffeine in 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 adults can safely consume doses up to 300 mg daily during pregnancy without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations. Advise keeping caffeine consumption below 300 mg daily during pregnancy. This is similar to the amount of caffeine found in about 3 cups of tea. There is also some evidence to suggest that a component found in oolong tea may inhibit folate metabolism and decrease folic acid concentrations during pregnancy. Folic acid levels should be monitored closely.

Pregnancy Possibly Unsafe

When used orally in large amounts. Caffeine from oolong tea crosses the placenta, producing fetal blood concentrations similar to maternal levels. In a cohort of mother/infant pairs with a median maternal plasma caffeine level of 168.5 ng/mL (range 29.5-650.5 ng/mL) during pregnancy, birth weights and lengths were lower in the 4th quartile of caffeine intake compared with the 1st. By age 7, heights and weights were lower by 1.5 cm and 1.1 kg respectively. In another cohort of mother/infant pairs with higher maternal pregnancy plasma caffeine levels, median 625.5 ng/mL (range 86.2 to 1994.7 ng/mL), heights at age 8 were 2.2 cm lower, but there was no difference in weights. 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 during pregnancy. This is similar to the amount of caffeine in about 3 cups of tea. High maternal doses of caffeine throughout pregnancy have 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.

Lactation Possibly Safe

When used orally in moderate amounts. Due to the caffeine content of oolong tea, caffeine intake should be closely monitored. 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 oolong tea might cause irritability and increased bowel activity in nursing infants. Large doses or excessive intake of oolong tea should be avoided during lactation.

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 — Oolong 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 — Oolong 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 Oolong 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 Oolong 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. Oolong 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.

Oolong Tea has been studied for:

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

Oolong Tea for depression

It is unclear if oral oolong tea is beneficial for depression in older adults.

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

We hold 75 real supplement products containing Oolong Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Oolong Tea. Even though Oolong 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 Oolong 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 Oolong Tea

Steady interest

#1,108 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 Oolong Tea reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Oolong 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 Oolong Tea

What is Oolong Tea?

Weight management
Mental alertness and energy
Heart health
Blood sugar support
Antioxidant support

Oolong tea is a traditional partially oxidized tea made from the same plant as green and black tea, and it provides caffeine and plant antioxidants. As a beverage it is generally considered safe for most healthy adults in moderate amounts, but evidence for specific health benefits like weight loss or blood sugar control is limited. If you have heart, blood pressure, or caffeine-sensitivity concerns, talk with your pharmacist or doctor.

Camellia sinensis · Theaceae · Leaves (partially oxidized) · Brewed tea, tea bags, loose leaf, extract capsules, powders

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

Oolong Tea: dosing

There is no official standardized dose of oolong tea. Most people simply drink it as a beverage — typically one to several cups per day brewed from tea bags or loose leaves.For extract capsules and powders, a single best dose has not been established, and products vary widely in strength and caffeine content. The safest approach is to follow the directions on the product label and not exceed them.Keep your total daily caffeine in mind, especially if you also drink coffee, other teas, or energy drinks.

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

Read the full Oolong 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 & Oolong Tea

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

8Major

518Moderate

126Minor

2,177No known interaction

8 Major 518 Moderate 126 Minor 2,177 No interaction

Major

8 interactions

Moderate

518 interactions

Showing 60 of 518 moderate interactions — see all 518 on the Oolong Tea page.

Minor

126 interactions

Showing 60 of 126 minor interactions — see all 126 on the Oolong Tea page.

No interaction 2,177 drugs checked — show the list

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

Showing the 60 most looked-up of 2,177 medications checked with no known interaction — see the full Oolong Tea list.

See the full Oolong Tea interactions page

See every supplement checked against Levothyroxine, ranked by severity

Evidence & sources

Oolong Tea References

The 112 references that drive our Oolong 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.
Merhav H, Amitai Y, Palti H, Godfrey S. Tea drinking and microcytic anemia in infants. Am J Clin Nutr 1985;41:1210-3.
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
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
The National Toxicology Program (NTP). Caffeine. Center for the Evaluation of Risks to Human Reproduction (CERHR). Available at: http://cerhr.niehs.nih.gov/common/caffeine.html.
Klebanoff MA, Levine RJ, DerSimonian R, et al. Maternal serum paraxanthine, a caffeine metabolite, and the risk of spontaneous abortion. N Engl J Med 1999;341:1639-44. PubMed
Eskenazi B. Caffeine—filtering the facts. N Engl J Med 1999;341:1688-9. PubMed
Fernandes O, Sabharwal M, Smiley T, et al. Moderate to heavy caffeine consumption during pregnancy and relationship to spontaneous abortion and abnormal fetal growth: a meta-analysis. Reprod Toxicol 1998;12:435-44. PubMed
Pollock BG, Wylie M, Stack JA, et al. Inhibition of caffeine metabolism by estrogen replacement therapy in postmenopausal women. J Clin Pharmacol 1999;39:936-40. PubMed
DiPiro JT, Talbert RL, Yee GC, et al; eds. Pharmacotherapy: A pathophysiologic approach. 4th ed. Stamford, CT: Appleton & Lange, 1999.
Nurminen ML, Niittynen L, Korpela R, Vapaatalo H. Coffee, caffeine and blood pressure: a critical review. Eur J Clin Nutr 1999;53:831-9. PubMed
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
FDA. Proposed rule: dietary supplements containing ephedrine alkaloids. Available at: www.verity.fda.gov (Accessed 25 January 2000).
Weisburger JH. Tea and health: the underlying mechanisms. Proc Soc Exp Biol Med 1999;220:271-5. PubMed
Briggs GB, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 1998.
Hagg S, Spigset O, Mjorndal T, Dahlqvist R. Effect of caffeine on clozapine pharmacokinetics in healthy volunteers. Br J Clin Pharmacol 2000;49:59-63. PubMed
Watson JM, Jenkins EJ, Hamilton P, et al. Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes. Diabetes Care 2000;23:455-9. PubMed
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
American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 2001;108:776-89. PubMed
Sinclair CJ, Geiger JD. Caffeine use in sports. A pharmacological review. J Sports Med Phys Fitness 2000;40:71-9.
Haller CA, Benowitz NL. Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids. N Engl J Med 2000;343:1833-8. PubMed
Ferrini RL, Barrett-Connor E. Caffeine intake and endogenous sex steroid levels in postmenopausal women. The Rancho Bernardo Study. Am J Epidemiol 1996:144:642-4. PubMed
Bell DG, Jacobs I, Ellerington K. Effect of caffeine and ephedrine ingestion on anaerobic exercise performance. Med Sci Sports Exerc 2001;33:1399-403. PubMed
Horner NK, Lampe JW. Potential mechanisms of diet therapy for fibrocystic breast conditions show inadequate evidence of effectiveness. J Am Diet Assoc 2000;100:1368-80. PubMed
Bracken MB, Triche EW, Belanger K, et al. Association of maternal caffeine consumption with decrements in fetal growth. Am J Epidemiol 2003;157:456-66.. PubMed
McGowan JD, Altman RE, Kanto WP Jr. Neonatal withdrawal symptoms after chronic maternal ingestion of caffeine. South Med J 1988;81:1092-4.. PubMed
Massey LK. Is caffeine a risk factor for bone loss in the elderly? Am J Clin Nutr 2001;74:569-70. PubMed
Dreher HM. The effect of caffeine reduction on sleep quality and well-being in persons with HIV. J Psychosom Res 2003;54:191-8.. PubMed
Kockler DR, McCarthy MW, Lawson CL. Seizure activity and unresponsiveness after hydroxycut ingestion. Pharmacotherapy 2001;21:647-51.. PubMed
Schechter MD, Timmons GD. Objectively measured hyperactivity--II. Caffeine and amphetamine effects. J Clin Pharmacol 1985;25:276-80.. PubMed
Nix D, Zelenitsky S, Symonds W, et al. The effect of fluconazole on the pharmacokinetics of caffeine in young and elderly subjects. Clin Pharmacol Ther 1992;51:183. DOI
Infante S, Baeza ML, Calvo M, et al. Anaphylaxis due to caffeine. Allergy 2003;58:681-2. PubMed
Massey LK, Whiting SJ. Caffeine, urinary calcium, calcium metabolism and bone. J Nutr 1993;123:1611-4. PubMed
Nawrot P, Jordan S, Eastwood J, et al. Effects of caffeine on human health. Food Addit Contam 2003;20:1-30. PubMed
May DC, Jarboe CH, VanBakel AB, Williams WM. Effects of cimetidine on caffeine disposition in smokers and nonsmokers. Clin Pharmacol Ther 1982;31:656-61. PubMed
Abernethy DR, Todd EL. Impairment of caffeine clearance by chronic use of low-dose oestrogen-containing oral contraceptives. Eur J Clin Pharmacol 1985;28:425-8. PubMed
Brown NJ, Ryder D, Branch RA. A pharmacodynamic interaction between caffeine and phenylpropanolamine. Clin Pharmacol Ther 1991;50:363-71. PubMed
Sanderink GJ, Bournique B, Stevens J, et al. Involvement of human CYP1A isoenzymes in the metabolism and drug interactions of riluzole in vitro. Pharmacol Exp Ther 1997;282:1465-72. DOI
Wahllander A, Paumgartner G. Effect of ketoconazole and terbinafine on the pharmacokinetics of caffeine in healthy volunteers. Eur J Clin Pharmacol 1989;37:279-83. PubMed
Carrillo JA, Benitez J. Clinically significant pharmacokinetic interactions between dietary caffeine and medications. Clin Pharmacokinet 2000;39:127-53. PubMed
Underwood DA. Which medications should be held before a pharmacologic or exercise stress test? Cleve Clin J Med 2002;69:449-50. 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 Oolong Tea and Levothyroxine Together: Common Questions

Is it safe to take Oolong Tea with Levothyroxine?

We do not list a known interaction between Oolong 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 Oolong 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 Oolong 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 Oolong 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 Oolong 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 Oolong Tea in each. That is a conversation for your prescriber, especially if Levothyroxine is being adjusted to a target.

How was the Oolong Tea and Levothyroxine combination checked?

Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Oolong Tea has documented interactions with 37 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 Oolong Tea interact with any other medications?

Yes. Oolong Tea has 652 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 — Oolong 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

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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.