Drug & supplement interaction

Tiratricol + Promethazine

Promethazine brand name: Phenergan.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Tiratricol and Promethazine 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 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

Tiratricol and Promethazine

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 Promethazine and Tiratricol 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.

Tiratricol safety at a glance

Tiratricol overall Avoid It is a potent thyroid-active drug that the FDA has warned against using in supplements.
Pregnancy Possibly Safe When used orally under medical supervision for treating fetal hypothyroidism. Read the full pregnancy detail
Breastfeeding Avoid It is unsafe and may pass thyroid effects to the infant, so avoid completely.

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 Promethazine and Tiratricol? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Promethazine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Promethazine is filed under 4 classifications — including phenothiazines, anticholinergic drugs, photosensitizing drugs. Tiratricol has documented interactions with 4 drug classes — the most serious being thyroid hormone (major), anticoagulant/antiplatelet drugs (moderate) and antidiabetes drugs (moderate) — and none of Promethazine’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

Tiratricol Does Interact With Other Medications

Tiratricol has 16 major, 209 moderate known drug interactions in our database — Promethazine isn’t one of them. If you take anything else, check it against the full list below.

Major 16 Moderate 209 No known interaction 2,605 (incl. Promethazine)
Taking anything else?

Check Another of Your Medications Against Tiratricol

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

What to actually watch for

No Interaction Found — But Data Suggests Tiratricol and Promethazine 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.

  • A fast or pounding heartbeat Additional detail

    Tiratricol

    “Orally, tiratricol has been associated with increased pulse and blood pressure, tachycardia, chest pain, cardiac arrhythmias, and heart attacks.”

    Tiratricol · Natural Medicines adverse-effect record, reported in arrhythmia.

    1 source cited
    1. 1605. US Food and Drug Administration (FDA). Dietary Supplements Containing Tiratricol: FDA Warns Consumers Against Consuming Tiratricol. Potent Thyroid Hormone Promoted as Dietary Supplement, Nov 21, 2000. Available at: https://www.fda.gov/inspections-complian

    Promethazine

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

  • Anxiety or restlessness / Trouble sleeping / Tiredness reported in 6.6% of FDA reports for Promethazine Additional detail

    Tiratricol

    “Orally, tiratricol is associated with symptoms of both thyrotoxicosis and hypothyroidism. Two young adults presented with symptoms of hypothyroidism, including lethargy, muscle weakness, and weight gain despite loss of appetite, after taking tiratricol 3000-4000 mcg daily for 5 weeks or 6000 mcg daily for 3 weeks.”

    Tiratricol · Natural Medicines adverse-effect record, reported in fatigue.

    3 sources cited
    1. 98213. Scally MC, Hodge A. A report of hypothyroidism induced by an over-the-counter fat loss supplement (Tiratricol). Int J Sport Nutr Exerc Metab 2003;13(1):112-6. PubMed
    2. 98214. Bauer BA, Elkin PL, Erickson D, Klee GG, Brennan MD. Symptomatic hyperthyroidism in a patient taking the dietary supplement tiratricol. Mayo Clin Proc 2002;77(6):587-90. PubMed
    3. 1620. Chow WS, Lam KS. An overweight woman with galactorrhoea. Postgrad Med J 1998;74:121-2. PubMed

    Promethazine

    Listed in the ADVERSE REACTIONS section of the FDA label for Promethazine, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Tiratricol but not commonly for Promethazine: an irregular heartbeat, stomach pain, reduced appetite and muscle weakness.

Effects for Promethazine come from the ADVERSE REACTIONS section of its FDA label; effects for Tiratricol come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 22,361 voluntary FDA FAERS reports for Promethazine that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Tiratricol in Pregnancy & Breastfeeding

Pregnancy Possibly Safe

When used orally under medical supervision for treating fetal hypothyroidism.

Pregnancy Likely Unsafe

When used orally without medical supervision due to possible risk of fetal heart damage; 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

From our Q&A

Questions About Tiratricol or Promethazine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Tiratricol or Promethazine, 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 Promethazine

This page covers Tiratricol only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Promethazine page lists 83 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Henbane (major), Scopolia (major), Alfalfa (moderate) and Angel's Trumpet (moderate).

By severity: 3 major · 57 moderate · 23 minor.

From our pharmacist’s overview on the Promethazine page

“Promethazine (Phenergan) is a phenothiazine antihistamine used for allergies, nausea, and motion sickness, and it is strongly anticholinergic on its own, causing dry mouth, blurred vision, drowsiness, and constipation. That is why the 83 supplements and herbs on this list deserve real attention, starting with the three rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Promethazine interaction page

How much people look this up

Where Tiratricol and Promethazine 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 Tiratricol
Top half

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

29 days ago today
Medication Promethazine
Top half

#1,206 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 Tiratricol reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Tiratricol and Promethazine 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 Tiratricol

What is Tiratricol?

  • Weight loss
  • Fat burning
  • Boosting metabolism
  • Bodybuilding and cutting
  • Thyroid-related supplementation

Tiratricol (also called TRIAC) is a powerful synthetic thyroid hormone metabolite, not a natural herb, and it has been illegally added to some weight-loss and bodybuilding supplements. It can cause serious heart and thyroid problems, and the U.S. FDA has warned consumers not to use products containing it. It is not a safe or approved dietary supplement, and you should avoid it.

Synthetic thyroid hormone metabolite (not a plant) · Tablets, capsules, powders (often sold in weight-loss or 'fat-burner' products)

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

Tiratricol: dosing

There is no safe, established dietary supplement dose for tiratricol, and we will not suggest one. It is not an approved supplement, and the FDA has warned against using products that contain it.Do not try to dose this on your own.

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

Read the full Tiratricol monograph & all interactions
Medication

About Promethazine

What Is Promethazine Used For?

Brand name: Phenergan

Promethazine is used for a wide range of conditions. Tablets, oral solution, and rectal suppositories (brands including Phenergan, Promethegan, and Phenadoz) are approved for seasonal and perennial allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, hives (urticaria), angioedema, dermographism, and allergic reactions to blood or plasma. They are also used for motion sickness (both prevention and active treatment), nausea and vomiting related to anesthesia and surgery, sedation, and as a helper medication alongside pain relievers after surgery.

Promethazine hydrochloride injection (brands including Phenergan and Promethazine HCl injection) is used for many of the same purposes but is reserved for situations where oral treatment is not possible — including allergic emergencies as an adjunct to epinephrine, sedation during labor, and as an aid during certain surgical procedures such as bronchoscopy and eye surgery.

Most-Reported Side Effects for Promethazine

From FAERS, the FDA’s public side-effect reporting system (22,614 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dependence 3,586 reports
Nausea 2,646 reports
Vomiting 1,802 reports
Fatigue 1,496 reports
Diarrhea 1,341 reports
See full Promethazine drug information
Keep checking

Other Drugs & Tiratricol

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

16Major
209Moderate
0Minor
2,604No known interaction
16 Major 209 Moderate 2,604 No interaction
Major

16 interactions

Moderate

209 interactions

Showing 60 of 209 moderate interactions — see all 209 on the Tiratricol page.

No interaction 2,604 drugs checked — show the list

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

Showing the 60 most looked-up of 2,604 medications checked with no known interaction — see the full Tiratricol list.

See the full Tiratricol interactions page
See every supplement checked against Promethazine, ranked by severity
Evidence & sources

Tiratricol References

The 12 references that drive our Tiratricol 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. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. US Food and Drug Administration (FDA). Dietary Supplements Containing Tiratricol: FDA Warns Consumers Against Consuming Tiratricol. Potent Thyroid Hormone Promoted as Dietary Supplement, Nov 21, 2000. Available at: https://www.fda.gov/inspections-complian
  3. Nicolini U, Venegoni E, Acaia B, et al. Prenatal treatment of fetal hypothyroidism: is there more than one option? Prenat Diagn 1996;16:443-8. DOI
  4. Asteria C, Rajanayagam O, Collingwood TN, et al. Prenatal diagnosis of thyroid hormone resistance. J Clin Endocrinol Metab 1999;84:405-10. PubMed
  5. Mueller-Gaertner HW, Schneider C. 3,5,3'-Triiodothyroacetic acid minimizes the pituitary thyrotrophin secretion in patients on levo-thyroxine therapy after ablative therapy for differentiated thyroid carcinoma. Clin Endocrinol (Oxf) 1988;28:345-51.
  6. Chow WS, Lam KS. An overweight woman with galactorrhoea. Postgrad Med J 1998;74:121-2. PubMed
  7. Lledo Carreres M, Lajo Garrido JL, Gonzalez Rico M, et al. Toxic internuclear ophthalmoplegia related to antiobesity treatment. Ann Pharmacother 1992;26:1457-8. PubMed
  8. Hawkey CM, Olsen EG, Symons C. Production of cardiac muscle abnormalities in offspring of rats receiving triiodothyroacetic acid (triac) and the effect of beta adrenergic blockade. Cardiovasc Res 1981;15:196-205. PubMed
  9. Olsen EG, Symons C, Hawkey C. Effect of triac on the developing heart. Lancet 1977;2:221-3. PubMed
  10. Scally MC, Hodge A. A report of hypothyroidism induced by an over-the-counter fat loss supplement (Tiratricol). Int J Sport Nutr Exerc Metab 2003;13(1):112-6. PubMed
  11. Bauer BA, Elkin PL, Erickson D, Klee GG, Brennan MD. Symptomatic hyperthyroidism in a patient taking the dietary supplement tiratricol. Mayo Clin Proc 2002;77(6):587-90. PubMed
  12. Cohen-Lehman J, Charitou MM, Klein I. Tiratricol-induced periodic paralysis: a review of nutraceuticals affecting thyroid function. Endocr Pract 2011;17(4):610-5. 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 Tiratricol and Promethazine Together: Common Questions

Is it safe to take Tiratricol with Promethazine?
We do not list a known interaction between Tiratricol and Promethazine. 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 Tiratricol and Promethazine have any of the same side effects?
Yes — our sources link each of them separately to 4 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.
How was the Tiratricol and Promethazine combination checked?
Interactions in our licensed database are recorded against drug classes. Promethazine is filed under 4 classifications, and Tiratricol has documented interactions with 4 drug classes — none of Promethazine'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 Tiratricol interact with any other medications?
Yes. Tiratricol has 225 documented drug interactions in our database — Promethazine 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 Promethazine interact with any supplements?
Yes. Promethazine has documented interactions with 83 supplements in our database — Tiratricol is not one of them. The Promethazine 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

Tiratricol monograph Uses, safety profile, and every drug interaction in one place Promethazine drug information The full plain-English guide to this medication Promethazine supplement interactions Every supplement checked against Promethazine, 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 12 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Promethazine and Tiratricol?

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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.