Drug & supplement interaction

Coenzyme Q10 + 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 Coenzyme Q10 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

Coenzyme Q10 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 Coenzyme Q10 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.

Coenzyme Q10 safety at a glance

Coenzyme Q10 overall Generally safe CoQ10 is generally well tolerated by most adults when used as directed.

Pregnancy Use caution There is not enough reliable safety data, so it is best to avoid unless your doctor advises otherwise.

Breastfeeding Use caution Safety while breastfeeding has not been well studied, so use caution and check with your doctor.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Pharmacist analysis

Although CoQ10 is considered relatively safe for most individuals, it does have some reported interactions that are important to be aware of.

This includes:

Antihypertensives: Clinical research has shown that CoQ10 can significantly lower blood pressure but conflicting results have been reported.

Warfarin: Research is conflicting but concomitant use of CoQ10 and warfarin might reduce the anticoagulant effects of warfarin.

Alkylating Agents: Antioxidants such as CoQ10 might also protect tumor cells from chemotherapeutic agents that work by inducing oxidative stress, such as alkylating agents (e.g., cyclophosphamide) and radiation therapy.

Outside of the interactions I've listed above, CoQ10 is generally considered safe to supplement with in most situations.

In fact, some individuals taking certain medications (e.g., 'Statins') may be recommended to take it.

If you have any questions about CoQ10 supplements, be sure to speak to your healthcare professional. We are always happy to answer questions on the matter as well!

— Dr. Brian Staiger, PharmD, BCPS

Still wondering about combining Levothyroxine and Coenzyme Q10? 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. Coenzyme Q10 has documented interactions with 3 drug classes — the most serious being alkylating agents (moderate), warfarin (coumadin) (moderate) and antihypertensive drugs (minor) — 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

Coenzyme Q10 Does Interact With Other Medications

Coenzyme Q10 has 26 moderate, 172 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.

Moderate 26 Minor 172 No known interaction 2,632 (incl. Levothyroxine)

Taking anything else?

Check Another of Your Medications Against Coenzyme Q10

Covers the 2,830 medications we’ve checked against Coenzyme Q10. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Coenzyme Q10 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. 2 of them are worth acting on rather than waiting out — marked below.

A heart attack Worth acting on Additional detail
Coenzyme Q10
“Palpitations have been reported as being possibly associated with coenzyme Q10 treatment. Death due to myocardial infarction occurred in one Parkinson disease patient taking coenzyme Q10; causality is unclear.”

Coenzyme Q10 · Natural Medicines adverse-effect record, reported in myocardial infarction (mi).
2 sources cited

89421. Parkinson Study Group QE3 Investigators, Beal MF, Oakes D, et al. A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit. JAMA Neurol. 2014;71(5):543-52.

15395. Storch A, Jost WH, Vieregge P, et al. Randomized, double-blind, placebo-controlled trial on symptomatic effects of coenzyme Q10 in Parkinson disease. Arch Neurol 2007;64:938-44. DOI
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Heart failure Worth acting on Additional detail
Coenzyme Q10
“Two of 143 participants in a case series reported skin itching after starting treatment with oral coenzyme Q10. Allergic rash has also been reported.

An itching exanthema was seen in two heart failure patients treated with intravenous coenzyme Q10.”

Coenzyme Q10 · Natural Medicines adverse-effect record, reported in congestive heart failure (chf).
4 sources cited

6047. Langsjoen PH, Langsjoen PH, Folkers K. Long-term efficacy and safety of coenzyme Q10 therapy for idiopathic dilated cardiomyopathy. Am J Cardiol 1990;65:521-3. PubMed

6409. Baggio E, Gandini R, Plauncher AC, et al. Italian multicenter study on the safety and efficacy of coenzyme Q10 as adjunctive therapy in heart failure. CoQ10 Drug Surveillance Investigators. Mol Aspects Med 1994;15 Suppl:S287-94. PubMed

11872. Sandor PS, Di Clemente L, Coppola G, et al. Efficacy of coenzyme Q10 in migraine prophylaxis: A randomized controlled trial. Neurology 2005;64:713-5. PubMed

44284. Ishiyama, T., Morita, Y., Toyama, S., Yamagami, T., and Tsukamoto, N. A clinical study of the effect of coenzyme Q on congestive heart failure. Jpn.Heart J 1976;17(1):32-42. PubMed
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

Coenzyme Q10

Recorded for Coenzyme Q10 in the same Natural Medicines adverse-effect record shown under A heart attack above.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Trouble sleeping / Tiredness / Headache Additional detail
Coenzyme Q10
“Headache and dizziness have been reported in human research. Insomnia has been reported as being possibly associated with coenzyme Q10 treatment. Cognitive decline, depression, and sudden falls were reported rarely in a clinical trial of patients with Huntington disease. Increased lethargy was reported for one patient treated with oral coenzyme Q10.”

Coenzyme Q10 · Natural Medicines adverse-effect record, reported in cluster headache.
6 sources cited

3365. Singh RB, Niaz MA, Rastogi SS, et al. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Hum Hypertens 1999;13:203-8. PubMed

11872. Sandor PS, Di Clemente L, Coppola G, et al. Efficacy of coenzyme Q10 in migraine prophylaxis: A randomized controlled trial. Neurology 2005;64:713-5. PubMed

43982. Rosenfeldt, F. L., Haas, S. J., Krum, H., Hadj, A., Ng, K., Leong, J. Y., and Watts, G. F. Coenzyme Q10 in the treatment of hypertension: a meta-analysis of the clinical trials. J Hum.Hypertens. 2007;21(4):297-306. PubMed

44330. Singh, R. B., Wander, G. S., Rastogi, A., Shukla, P. K., Mittal, A., Sharma, J. P., Mehrotra, S. K., Kapoor, R., and Chopra, R. K. Randomized, double-blind placebo-controlled trial of coenzyme Q10 in patients with acute myocardial infarction. Cardiovasc. PubMed

109392. Hansen KS, Mogensen TH, Agergaard J, et al. High-dose coenzyme Q10 therapy versus placebo in patients with post COVID-19 condition: A randomized, phase 2, crossover trial. Lancet Reg Health Eur 2022. PubMed

89421. Parkinson Study Group QE3 Investigators, Beal MF, Oakes D, et al. A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit. JAMA Neurol. 2014;71(5):543-52.
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Itching / A skin rash Additional detail

Coenzyme Q10

Recorded for Coenzyme Q10 in the same Natural Medicines adverse-effect record shown under Heart failure above.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Diarrhea / Vomiting Additional detail
Coenzyme Q10
“Gastrointestinal side effects of coenzyme Q10 have included nausea, vomiting, epigastric discomfort, constipation, diarrhea, stomach upset, loss of appetite, heartburn, and flatulence, although this occurs in less than 1% of patients. In one clinical study, gastrointestinal bleeding in association with angiodysplasia has been reported to be possibly related to coenzyme Q10 treatment.”

Coenzyme Q10 · Natural Medicines adverse-effect record, reported in constipation.
6 sources cited

3365. Singh RB, Niaz MA, Rastogi SS, et al. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Hum Hypertens 1999;13:203-8. PubMed

6409. Baggio E, Gandini R, Plauncher AC, et al. Italian multicenter study on the safety and efficacy of coenzyme Q10 as adjunctive therapy in heart failure. CoQ10 Drug Surveillance Investigators. Mol Aspects Med 1994;15 Suppl:S287-94. PubMed

8907. Burke BE, Neuenschwander R, Olson RD. Randomized, double-blind, placebo-controlled trial of coenzyme Q10 in isolated systolic hypertension. South Med J 2001;94:1112-7. PubMed

10152. Singh RB, Neki NS, Kartikey K, et al. Effect of coenzyme Q10 on risk of atherosclerosis in patients with recent myocardial infarction. Mol Cell Biochem 2003;246:75-82. DOI

43982. Rosenfeldt, F. L., Haas, S. J., Krum, H., Hadj, A., Ng, K., Leong, J. Y., and Watts, G. F. Coenzyme Q10 in the treatment of hypertension: a meta-analysis of the clinical trials. J Hum.Hypertens. 2007;21(4):297-306. PubMed

44172. Gane, E. J., Weilert, F., Orr, D. W., Keogh, G. F., Gibson, M., Lockhart, M. M., Frampton, C. M., Taylor, K. M., Smith, R. A., and Murphy, M. P. The mitochondria-targeted anti-oxidant mitoquinone decreases liver damage in a phase II study of hepatitis C
Levothyroxine

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

Showing the 10 most notable of 11 shared effects — ranked by how unusual each one is, not just whether both lists mention it.

Reported for Coenzyme Q10 but not commonly for Levothyroxine: bleeding in the gut, stomach upset, reduced appetite and a low platelet count.

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Coenzyme Q10 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.

How to take them

Some Levothyroxine Products Have a Food Rule — Coenzyme Q10 Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10 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. Coenzyme Q10 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.

Coenzyme Q10 has been studied for:

Depression studied, not established Coenzyme Q10 has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

Coenzyme Q10 for depression

It is unclear if oral coenzyme Q10 is beneficial for depression.

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 Coenzyme Q10 for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10 as Part of a Dietary Supplement Product? Check It for Interactions

We hold 6,926 real supplement products containing Coenzyme Q10, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Coenzyme Q10. Even though Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10

Top 5%

#36 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 Coenzyme Q10 reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Coenzyme Q10 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 Coenzyme Q10

What is Coenzyme Q10?

Heart health
Statin-related muscle aches
Migraine prevention
Energy and fatigue
Aging and antioxidant support

CoQ10 is a vitamin-like substance your body makes naturally that helps cells produce energy and acts as an antioxidant. It is generally well tolerated and is most studied for heart conditions, statin-related muscle symptoms, and migraine prevention, though the strength of the evidence varies. Talk with your pharmacist or doctor before starting it, especially if you take heart or blood pressure medicines.

Not applicable (naturally made in the body; supplements are produced by fermentation or synthesis) · Capsules, softgels, tablets, chewables, liquid, topical creams

An interaction check asks whether these two react with each other — it does not ask whether Coenzyme Q10 is a good idea for someone in your situation. Here is what our Coenzyme Q10 record says about it on its own.

Coenzyme Q10: dosing

There is no single official or standardized dose of CoQ10, and the amount studied has varied widely depending on the condition. Products also differ in their form (ubiquinone versus ubiquinol) and how well they are absorbed.Because CoQ10 is fat-soluble, it is generally absorbed better when taken with a meal that contains some fat. They can help you choose a reasonable dose and a quality product.

From our Coenzyme Q10 monograph — the full record covers uses, side effects and every documented interaction.

Read the full Coenzyme Q10 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 & Coenzyme Q10

Browse every other medication we’ve checked against Coenzyme Q10 — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major

26Moderate

172Minor

2,631No known interaction

26 Moderate 172 Minor 2,631 No interaction

Moderate

26 interactions

Minor

172 interactions

Showing 60 of 172 minor interactions — see all 172 on the Coenzyme Q10 page.

No interaction 2,631 drugs checked — show the list

We also checked Coenzyme Q10 against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,631 medications checked with no known interaction — see the full Coenzyme Q10 list.

See the full Coenzyme Q10 interactions page

See every supplement checked against Levothyroxine, ranked by severity

Evidence & sources

Coenzyme Q10 References

The 40 references that drive our Coenzyme Q10 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.

Kamikawa T, Kobayashi A, Yamashita T, et al. Effects of coenzyme Q10 on exercise tolerance in chronic stable angina pectoris. Am J Cardiol 1985;56:247-51. PubMed
Langsjoen P, Willis R, Folkers K. Treatment of essential hypertension with coenzyme Q10. Mol Aspects Med 1994;S265-72. PubMed
Spigset O. Reduced effect of warfarin caused by ubidecarenone. Lancet 1994;334:1372-3. PubMed
Singh RB, Niaz MA, Rastogi SS, et al. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Hum Hypertens 1999;13:203-8. PubMed
Portakal O, Ozkaya O, Erden Inal M, et al. Coenzyme Q10 concentrations and antioxidant status in tissues of breast cancer patients. Clin Biochem 2000;33:279-84. PubMed
Lund EL, Quistorff B, Spang-Thomsen M, Kristjansen PE. Effect of radiation therapy on small-cell lung cancer is reduced by ubiquinone intake. Folia Microbiol (Praha) 1998;43:505-6. PubMed
Langsjoen PH, Langsjoen PH, Folkers K. Long-term efficacy and safety of coenzyme Q10 therapy for idiopathic dilated cardiomyopathy. Am J Cardiol 1990;65:521-3. PubMed
Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm 2000;57:1221-7. DOI
Landbo C, Almdal TP. [Interaction between warfarin and coenzyme Q10]. Ugeskr Laeger 1998;160:3226-7.
Baggio E, Gandini R, Plauncher AC, et al. Italian multicenter study on the safety and efficacy of coenzyme Q10 as adjunctive therapy in heart failure. CoQ10 Drug Surveillance Investigators. Mol Aspects Med 1994;15 Suppl:S287-94. PubMed
Burke BE, Neuenschwander R, Olson RD. Randomized, double-blind, placebo-controlled trial of coenzyme Q10 in isolated systolic hypertension. South Med J 2001;94:1112-7. PubMed
The Huntington Study Group. A randomized, placebo-controlled trial of coenzyme Q10 and remacemide in Huntington's disease. Neurology 2001;57:397-404.
Hodgson JM, Watts GF, Playford DA, et al. Coenzyme Q10 improves blood pressure and glycaemic control: a controlled trial in subjects with type 2 diabetes. Eur J Clin Nutr 2002;56:1137-42. PubMed
Singh RB, Neki NS, Kartikey K, et al. Effect of coenzyme Q10 on risk of atherosclerosis in patients with recent myocardial infarction. Mol Cell Biochem 2003;246:75-82. DOI
Porterfield LM. Why did the response to warfarin change? RN 2000;63:107.
Sandor PS, Di Clemente L, Coppola G, et al. Efficacy of coenzyme Q10 in migraine prophylaxis: A randomized controlled trial. Neurology 2005;64:713-5. PubMed
Engelsen J, Nielsen JD, Winther K. Effect of coenzyme Q10 and Ginkgo biloba on warfarin dosage in stable, long-term warfarin treated outpatients. A randomised, double blind, placebo-crossover trial. Thromb Haemost 2002;87:1075-6. DOI
Berman M, Erman A, Ben-Gal T, et al. Coenzyme Q10 in patients with end-stage heart failure awaiting cardiac transplantation: a randomized, placebo-controlled study. Clin Cardiol 2004;27:295–9. PubMed
Storch A, Jost WH, Vieregge P, et al. Randomized, double-blind, placebo-controlled trial on symptomatic effects of coenzyme Q10 in Parkinson disease. Arch Neurol 2007;64:938-44. DOI
Digiesi V, Cantini F, Oradei A, et al. Coenzyme Q10 in essential hypertension. Mol Aspects Med 1994;15 Suppl:s257-63. PubMed
Yamagami T, Takagi M, Akagami H, et al. Effect of coenzyme Q10 on essential hypertension, a double blind controlled study. In: Folkers KA, Yamamura Y, eds. Biomedical and Clinical Aspects of Coenzyme Q, Vol. 5. Amsterdam: Elsevier Science Publications, 19
Ho MJ, Bellusci A, Wright JM. Blood pressure lowering efficacy of coenzyme Q10 for primary hypertension (review). Cochrane Database Syst Rev 2009;(4):CD007435. PubMed
Rosenfeldt, F. L., Haas, S. J., Krum, H., Hadj, A., Ng, K., Leong, J. Y., and Watts, G. F. Coenzyme Q10 in the treatment of hypertension: a meta-analysis of the clinical trials. J Hum.Hypertens. 2007;21(4):297-306. PubMed
Stamelou, M., Reuss, A., Pilatus, U., Magerkurth, J., Niklowitz, P., Eggert, K. M., Krisp, A., Menke, T., Schade-Brittinger, C., Oertel, W. H., and Hoglinger, G. U. Short-term effects of coenzyme Q10 in progressive supranuclear palsy: a randomized, place DOI
Keogh A, Fenton S, Leslie C, et al. Randomised double-blind, placebo-controlled trial of coenzyme Q, therapy in class II and III systolic heart failure. Heart Lung Circ. 2003;12:135-41.
Gane, E. J., Weilert, F., Orr, D. W., Keogh, G. F., Gibson, M., Lockhart, M. M., Frampton, C. M., Taylor, K. M., Smith, R. A., and Murphy, M. P. The mitochondria-targeted anti-oxidant mitoquinone decreases liver damage in a phase II study of hepatitis C
Lynch, D. R., Perlman, S. L., and Meier, T. A phase 3, double-blind, placebo-controlled trial of idebenone in friedreich ataxia. Arch Neurol. 2010;67(8):941-947. PubMed
Young, J. M., Florkowski, C. M., Molyneux, S. L., McEwan, R. G., Frampton, C. M., Nicholls, M. G., Scott, R. S., and George, P. M. A randomized, double-blind, placebo-controlled crossover study of coenzyme Q10 therapy in hypertensive patients with the me
Ishiyama, T., Morita, Y., Toyama, S., Yamagami, T., and Tsukamoto, N. A clinical study of the effect of coenzyme Q on congestive heart failure. Jpn.Heart J 1976;17(1):32-42. PubMed
Matthews, P. M., Ford, B., Dandurand, R. J., Eidelman, D. H., O'Connor, D., Sherwin, A., Karpati, G., Andermann, F., and Arnold, D. L. Coenzyme Q10 with multiple vitamins is generally ineffective in treatment of mitochondrial disease. Neurology 1993;43(5
Malm, C., Svensson, M., Sjoberg, B., Ekblom, B., and Sjodin, B. Supplementation with ubiquinone-10 causes cellular damage during intense exercise. Acta Physiol Scand. 1996;157(4):511-512. PubMed
Singh, R. B., Wander, G. S., Rastogi, A., Shukla, P. K., Mittal, A., Sharma, J. P., Mehrotra, S. K., Kapoor, R., and Chopra, R. K. Randomized, double-blind placebo-controlled trial of coenzyme Q10 in patients with acute myocardial infarction. Cardiovasc. PubMed
Digiesi V, Cantini F, and Brodbeck B. Effect of coenzyme Q10 on essential arterial hypertension. Current Therapeutic Research 1990;47(5):841-845.
Parkinson Study Group QE3 Investigators, Beal MF, Oakes D, et al. A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit. JAMA Neurol. 2014;71(5):543-52.
Alehagen U, Johansson P, Bjornstedt M, et al. Cardiovascular mortality and N-terminal-proBNP reduced after combined selenium and coenzyme Q10 supplementation: A 5-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citi
Ho MJ, Li EC, Wright JM. Blood pressure lowering efficacy of coenzyme Q10 for primary hypertension. Cochrane Database Syst Rev. 2016 Mar 3;3:CD007435. doi: 10.1002/14651858.CD007435.pub3. PubMed
Tabrizi R, Akbari M, Sharifi N, Lankarani KB, Moosazadeh M, Kolahdooz F, et al. The effects of coenzyme Q10 supplementation on blood pressures among patients with metabolic diseases: a systematic review and meta-analysis of randomized controlled trials. PubMed
Tsai IC, Hsu CW, Chang CH, Tseng PT, Chang KV. Effectiveness of coenzyme Q10 supplementation for reducing fatigue: A systematic review and meta-analysis of randomized controlled trials. Front Pharmacol 2022;13:883251. PubMed
Yaghini O, Hoseini N, Ghazavi MR, et al. A comparative study on the efficacy of coenzyme Q10 and amitriptyline in the prophylactic treatment of migraine headaches in children: A randomized controlled trial. Adv Biomed Res 2022;11:43. PubMed
Hansen KS, Mogensen TH, Agergaard J, et al. High-dose coenzyme Q10 therapy versus placebo in patients with post COVID-19 condition: A randomized, phase 2, crossover trial. Lancet Reg Health Eur 2022. PubMed

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 Coenzyme Q10 and Levothyroxine Together: Common Questions

Is it safe to take Coenzyme Q10 with Levothyroxine?

We do not list a known interaction between Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10 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 Coenzyme Q10 in each. That is a conversation for your prescriber, especially if Levothyroxine is being adjusted to a target.

How was the Coenzyme Q10 and Levothyroxine combination checked?

Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Coenzyme Q10 has documented interactions with 3 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 Coenzyme Q10 interact with any other medications?

Yes. Coenzyme Q10 has 198 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 — Coenzyme Q10 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.