Drug & supplement interaction

Coleus + Thyroid Hormone

Thyroid Hormone brand name: Etwon.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Coleus and Thyroid Hormone 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.

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Interaction report

Coleus and Thyroid Hormone

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 Thyroid Hormone and Coleus 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.

Coleus safety at a glance

Coleus overall Use caution May lower blood pressure and is not well studied for long-term use, so use with care and professional guidance.
Pregnancy Possibly Unsafe When used orally. Evidence from animal research suggests that high doses of coleus can inhibit embryo implantation and/or delay fetal development; avoid using. Read the full pregnancy detail
Breastfeeding Avoid Not enough safety data; avoid use while breastfeeding.

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 Thyroid Hormone and Coleus? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Thyroid Hormone

Interactions in our licensed database are recorded against drug classes, not just single drug names. Thyroid Hormone is filed under 2 classifications — including oral drugs. Coleus has documented interactions with 7 drug classes — the most serious being calcium channel blockers (major), nitrates (major) and anticoagulant/antiplatelet drugs (moderate) — and none of Thyroid Hormone’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

Coleus Does Interact With Other Medications

Coleus has 29 major, 886 moderate known drug interactions in our database — Thyroid Hormone isn’t one of them. If you take anything else, check it against the full list below.

Major 29 Moderate 886 No known interaction 1,915 (incl. Thyroid Hormone)
Taking anything else?

Check Another of Your Medications Against Coleus

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

What to actually watch for

What Coleus Itself Has Been Linked To

This is not an interaction — nothing below involves Thyroid Hormone. It is the side-effect record for Coleus on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Coleus, this list is the first place to look.

  • Eye irritation or redness / Tremor or shakiness / Anxiety or restlessness Additional detail

    “Orally, intravenously, ophthalmologically, and by inhalation, coleus seems to be well tolerated.

    Most Common Adverse Effects:

    Orally: Constipation, diarrhea, nausea, vomiting.

    Intravenously: Flushing, hypotension, tachycardia.

    Ophthalmologically: Conjunctival hyperemia, stinging eyes.

    Inhalation: Irritation of the respiratory tract, restlessness, tremor.”

    Coleus · Natural Medicines adverse-effect record, reported in constipation.

  • Flushing / A fast or pounding heartbeat / Low blood pressure Additional detail

    “Intravenously, the coleus constituent, forskolin, can cause tachycardia, flushing and hypotension.”

    Coleus · Natural Medicines adverse-effect record, reported in hypotension.

    3 sources cited
    1. 7279. Kramer W, Thormann J, Kindler M, Schlepper M. Effects of forskolin on left ventricular function in dilated cardiomyopathy. Arzneimittelforschung 1987;37:364-7.
    2. 44424. Schlepper, M., Thormann, J., and Mitrovic, V. Cardiovascular effects of forskolin and phosphodiesterase-III inhibitors. Basic Res Cardiol 1989;84 Suppl 1:197-212. PubMed
    3. 44431. Lindner, E., Dohadwalla, A. N., and Bhattacharya, B. K. Positive inotropic and blood pressure lowering activity of a diterpene derivative isolated from Coleus forskohli: Forskolin. Arzneimittelforschung 1978;28(2):284-289.
  • Cough Additional detail

    “Inhalation of forskolin, a constituent of coleus, can cause throat and upper respiratory tract irritation, and mild to moderate cough.”

    Coleus · Natural Medicines adverse-effect record, reported in cough.

    1 source cited
    1. 7281. Bauer K, Dietersdorfer F, Kaspar S, et al. Pharmacodynamic effects of inhaled dry powder formulations of fenoterol and colforsin in asthma. Clin Pharmacol Ther 1993;53:76-83. PubMed
  • Constipation / Diarrhea Additional detail

    “Orally, coleus can cause dose-related diarrhea and other gastrointestinal symptoms. Increased bowel movements and loose stools have been reported in 1 of 15 patients taking coleus extract in a clinical trial. Some retrospective evidence reports about a 10% rate of gastrointestinal adverse effects from oral coleus use; 81% of these adverse effects were related to diarrhea.”

    Coleus · Natural Medicines adverse-effect record, reported in constipation.

    2 sources cited
    1. 91885. Loftus HL, Astell KJ, Mathai ML, et al. Coleus forskohlii Extract Supplementation in Conjunction with a Hypocaloric Diet Reduces the Risk Factors of Metabolic Syndrome in Overweight and Obese Subjects: A Randomized Controlled Trial. Nutrients. 2015;7(11): PubMed
    2. 100851. Nishijima C, Chiba T, Sato Y, Umegaki K. Nationwide Online Survey Enables the Reevaluation of the Safety of Coleus forskohlii Extract Intake Based on the Adverse Event Frequencies. Nutrients. 2019;11(4). pii: E866. PubMed
  • A skin rash Additional detail

    “Two cases of contact dermatitis have been reported following airborne exposure to coleus.”

    Coleus · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 44426. Dooms-Goossens, A., Borghijs, A., Degreef, H., Devriese, E. G., and Geuns, J. M. Airborne contact dermatitis to Coleus. Contact Dermatitis 1987;17(2):109-110. PubMed
    2. 44418. van Hecke, E., Hindryckx, P., Geuns, J. M., and Devriese, E. Airborne contact dermatitis from coleus in a housewife. Contact Dermatitis 1991;25(2):128-129. PubMed

Showing the 10 most notable of 12 recorded effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

Everything above comes from the Natural Medicines adverse-effect record for Coleus — expand a row for the licensed statement it rests on. We haven’t matched Thyroid Hormone to its FDA label in our system yet, so we can’t compare its own side-effect list here — the leaflet that comes with your prescription is the authoritative list for Thyroid Hormone.

Special populations

Coleus in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When used orally. Evidence from animal research suggests that high doses of coleus can inhibit embryo implantation and/or delay fetal development; avoid using.

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

Everything else you take

See Every Supplement That Interacts With Thyroid Hormone

This page covers Coleus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Thyroid Hormone page lists 38 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 · 26 moderate · 10 minor.

From our pharmacist’s overview on the Thyroid Hormone page

“The riskiest pairing on this page is tiratricol, which is itself a thyroid compound, so taking it alongside thyroid hormone (Etwon) stacks two doses of the same signal. It shares the list's only two major ratings with activated charcoal, which soaks up medication in the gut before the body can absorb it.”

Reviewed by 2 · Jul 18, 2026

Open the Thyroid Hormone interaction page

One more smart check

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

We hold 803 real supplement products containing Coleus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Coleus. Even though Coleus itself has no known interaction with Thyroid Hormone, 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 Coleus and Thyroid Hormone 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 Coleus
Top 25%

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

29 days ago today
Medication Thyroid Hormone
Top 10%

#191 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 Coleus reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Coleus and Thyroid Hormone 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 .
Supplement

About Coleus

What is Coleus?

Coleus
  • Weight management
  • Asthma and breathing
  • High blood pressure
  • Heart conditions
  • Glaucoma (eye pressure)
  • Exercise and body composition

Coleus is a plant from the mint family whose root contains a compound called forskolin, often marketed for weight loss, asthma, and heart health. While early lab and small human studies are interesting, solid proof that Coleus supplements help any of these conditions is limited. Talk to your pharmacist or doctor before using it, especially if you have heart problems or low blood pressure.

Coleus forskohlii · Lamiaceae · Roots (source of forskolin) · Capsules, tablets, standardized extracts (often standardized to forskolin), powders

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

Coleus: dosing

There is no official, well-established dose for Coleus. Products vary widely in strength and are often standardized to a certain percentage of forskolin, but the best dose for any health goal has not been proven.The safest approach is to follow the directions on the product label and not exceed the recommended amount.

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

Read the full Coleus monograph & all interactions
Keep checking

Other Drugs & Coleus

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

29Major
886Moderate
0Minor
1,914No known interaction
29 Major 886 Moderate 1,914 No interaction
Major

29 interactions

Moderate

886 interactions

Showing 60 of 886 moderate interactions — see all 886 on the Coleus page.

No interaction 1,914 drugs checked — show the list

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

Showing the 60 most looked-up of 1,914 medications checked with no known interaction — see the full Coleus list.

See the full Coleus interactions page
See every supplement checked against Thyroid Hormone, ranked by severity
Evidence & sources

Coleus References

The 16 references that drive our Coleus monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Baumann G, Felix S, Sattelberger U, Klein G. Cardiovascular effects of forskolin (HL-362) in patients with idiopathic congestiv cardiomyopathy. A comparative study with dobutamine and sodium nitroprusside. J Cardiovasc Pharmacol 1990;16:93-100.
  2. Kramer W, Thormann J, Kindler M, Schlepper M. Effects of forskolin on left ventricular function in dilated cardiomyopathy. Arzneimittelforschung 1987;37:364-7.
  3. Bauer K, Dietersdorfer F, Kaspar S, et al. Pharmacodynamic effects of inhaled dry powder formulations of fenoterol and colforsin in asthma. Clin Pharmacol Ther 1993;53:76-83. PubMed
  4. Christenson JT, Thulesius O, Nazzal MM. The effect of forskolin on blood flow, platelet metabolism, aggregation and ATP release. Vasa 1995;24:56-61.
  5. Agarwal KC, Zielinski BA, Maitra RS. Significance of plasma adenosine in the antiplatelet activity of forskolin: potentiation by dipyridamole and dilazep. Thromb Haemost 1989;61:106-10. DOI
  6. Agarwal KC, Parks RE. Forskolin: a potential antimetastatic agent. Int J Cancer 1983;32:801-4. PubMed
  7. Almeida, F. C. and Lemonica, I. P. The toxic effects of Coleus barbatus B. on the different periods of pregnancy in rats. J Ethnopharmacol 2000;73(1-2):53-60. PubMed
  8. Ding, X. and Staudinger, J. L. Induction of drug metabolism by forskolin: the role of the pregnane X receptor and the protein kinase a signal transduction pathway. J Pharmacol Exp Ther 2005;312(2):849-856. PubMed
  9. Staudinger, J. L., Ding, X., and Lichti, K. Pregnane X receptor and natural products: beyond drug-drug interactions. Expert.Opin Drug Metab Toxicol 2006;2(6):847-857. PubMed
  10. van Hecke, E., Hindryckx, P., Geuns, J. M., and Devriese, E. Airborne contact dermatitis from coleus in a housewife. Contact Dermatitis 1991;25(2):128-129. PubMed
  11. Schlepper, M., Thormann, J., and Mitrovic, V. Cardiovascular effects of forskolin and phosphodiesterase-III inhibitors. Basic Res Cardiol 1989;84 Suppl 1:197-212. PubMed
  12. Dooms-Goossens, A., Borghijs, A., Degreef, H., Devriese, E. G., and Geuns, J. M. Airborne contact dermatitis to Coleus. Contact Dermatitis 1987;17(2):109-110. PubMed
  13. Lindner, E., Dohadwalla, A. N., and Bhattacharya, B. K. Positive inotropic and blood pressure lowering activity of a diterpene derivative isolated from Coleus forskohli: Forskolin. Arzneimittelforschung 1978;28(2):284-289.
  14. Loftus HL, Astell KJ, Mathai ML, et al. Coleus forskohlii Extract Supplementation in Conjunction with a Hypocaloric Diet Reduces the Risk Factors of Metabolic Syndrome in Overweight and Obese Subjects: A Randomized Controlled Trial. Nutrients. 2015;7(11): PubMed
  15. Yokotani K, Chiba T, Sato Y, et al. Hepatic cytochrome P450 mediates interaction between warfarin and Coleus forskohlii extract in vivo and in vitro. J Pharm Pharmacol. 2012;64(12):1793-801.

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 Coleus and Thyroid Hormone Together: Common Questions

Is it safe to take Coleus with Thyroid Hormone?
We do not list a known interaction between Coleus and Thyroid Hormone. 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.
How was the Coleus and Thyroid Hormone combination checked?
Interactions in our licensed database are recorded against drug classes. Thyroid Hormone is filed under 2 classifications, and Coleus has documented interactions with 7 drug classes — none of Thyroid Hormone'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 Coleus interact with any other medications?
Yes. Coleus has 915 documented drug interactions in our database — Thyroid Hormone 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 Thyroid Hormone interact with any supplements?
Yes. Thyroid Hormone has documented interactions with 38 supplements in our database — Coleus is not one of them. The Thyroid Hormone 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

Coleus monograph Uses, safety profile, and every drug interaction in one place Thyroid Hormone supplement interactions Every supplement checked against Thyroid Hormone, 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 16 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Thyroid Hormone and Coleus?

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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.