Drug & supplement interaction

Thyroid Extract + Tretinoin, Benzoyl Peroxide

Tretinoin, Benzoyl Peroxide brand name: Twyneo.

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 Thyroid Extract and Tretinoin, Benzoyl Peroxide 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

Thyroid Extract and Tretinoin, Benzoyl Peroxide

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 Tretinoin, Benzoyl Peroxide and Thyroid Extract 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.

Thyroid Extract safety at a glance

Thyroid Extract overall Use caution OTC thyroid extracts may contain active hormones in unknown amounts and should not be used without medical supervision.
Pregnancy Avoid Thyroid hormone levels must be carefully controlled in pregnancy, so do not use unregulated extracts.
Breastfeeding Avoid Unregulated thyroid hormone exposure could affect the nursing infant, so avoid unless directed by a doctor.

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

Still wondering about combining Tretinoin, Benzoyl Peroxide and Thyroid Extract? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Tretinoin, Benzoyl Peroxide

Interactions in our licensed database are recorded against drug classes, not just single drug names. Tretinoin, Benzoyl Peroxide is filed under 4 classifications — including retinoids, cytochrome p450 2c8 (cyp2c8) substrates, topical drugs. Thyroid Extract has documented interactions with 2 drug classes — the most serious being levothyroxine (synthroid, others) (moderate) and oral drugs (minor) — and none of Tretinoin, Benzoyl Peroxide’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

Thyroid Extract Does Interact With Other Medications

Thyroid Extract has 3 moderate, 2,019 minor known drug interactions in our database — Tretinoin, Benzoyl Peroxide isn’t one of them. If you take anything else, check it against the full list below.

Moderate 3 Minor 2,019 No known interaction 808 (incl. Tretinoin, Benzoyl Peroxide)
Taking anything else?

Check Another of Your Medications Against Thyroid Extract

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

What to actually watch for

No Interaction Found — But Data Suggests Thyroid Extract and Tretinoin, Benzoyl Peroxide May Share a Side Effect

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. One of them is worth acting on rather than waiting out — marked below.

  • Hives Worth acting on Additional detail

    Thyroid Extract

    “A 30-year-old female with allergic rhinitis and multinodular goiter developed allergic urticaria after treatment with desiccated thyroid extract.”

    Thyroid Extract · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    1 source cited
    1. 28619. Benvenga, S., Trimarchi, F., Barbera, C., Costante, G., Morabito, S., Barberio, G., and Consolo, F. Circulating immunoglobulin E (IgE) antibodies to L-thyroxine in a euthyroid patient with multinodular goiter and allergic rhinitis. J Endocrinol Invest 198 PubMed

    “In one case report, a teenage female taking thyroid extract developed multiple nevi on the skin. In another case report, a 30-year-old female with allergic rhinitis and multinodular goiter developed allergic urticaria after treatment with desiccated thyroid extract.”

    Thyroid Extract · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    2 sources cited
    1. 28622. Tofahrn, J. and Hundeiker, M. [Nevus eruption following thyroidin with spontaneous involution]. Z Hautkr 1976;51(15):617-620.
    2. 28619. Benvenga, S., Trimarchi, F., Barbera, C., Costante, G., Morabito, S., Barberio, G., and Consolo, F. Circulating immunoglobulin E (IgE) antibodies to L-thyroxine in a euthyroid patient with multinodular goiter and allergic rhinitis. J Endocrinol Invest 198 PubMed

    Tretinoin, Benzoyl Peroxide

    Listed in the ADVERSE REACTIONS section of the FDA label for Tretinoin, Benzoyl Peroxide. Read the label on DailyMed ›

Reported for Thyroid Extract but not commonly for Tretinoin, Benzoyl Peroxide: raised blood pressure, a fast or pounding heartbeat, anxiety or restlessness and vomiting.

Effects for Tretinoin, Benzoyl Peroxide come from the ADVERSE REACTIONS section of its FDA label; effects for Thyroid Extract 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.

Everything else you take

See Every Supplement That Interacts With Tretinoin, Benzoyl Peroxide

This page covers Thyroid Extract only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tretinoin, Benzoyl Peroxide page lists 35 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Vitamin A (major), African Wild Potato (moderate), Alfalfa (moderate), Angelica Archangelica (moderate) and Arrach (moderate).

By severity: 1 major · 30 moderate · 4 minor.

From our pharmacist’s overview on the Tretinoin, Benzoyl Peroxide page

“Twyneo pairs tretinoin, a vitamin A derivative, with benzoyl peroxide in an acne cream, and its interaction list deserves genuine care. The single major-rated entry among the 35 supplements on file is vitamin A itself; stacking supplements on a drug built from vitamin A can push levels toward toxicity, so that pairing is the one to und…”

Reviewed by 2 · Jul 18, 2026

Open the Tretinoin, Benzoyl Peroxide interaction page

How much people look this up

Where Thyroid Extract and Tretinoin, Benzoyl Peroxide 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 Thyroid Extract
Top half

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

29 days ago today
Medication Tretinoin, Benzoyl Peroxide
Steady interest

#2,605 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 Thyroid Extract reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Thyroid Extract and Tretinoin, Benzoyl Peroxide records this page draws on were last updated July 10, 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 Thyroid Extract

What is Thyroid Extract?

Thyroid Extract
  • Hypothyroidism (underactive thyroid)
  • Fatigue and low energy
  • Weight management
  • Sluggish metabolism
  • General thyroid support

Thyroid extract supplements are made from dried animal thyroid gland and may contain real thyroid hormones (T3 and T4), but the amounts in over-the-counter products are not standardized and can be unpredictable. Self-treating a thyroid problem with these supplements can be risky, so always work with a doctor or pharmacist and use prescription thyroid medicine when treatment is needed.

Animal thyroid gland tissue (commonly from pigs or cows) · Capsules, tablets, dried powder

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

Thyroid Extract: dosing

There is no established or standardized safe dose for over-the-counter thyroid extract supplements, partly because their hormone content varies from product to product. This is a major reason healthcare providers are cautious about them.If thyroid hormone replacement is truly needed, it should be prescribed and monitored by a doctor, often with regular blood tests to fine-tune the dose. Never adjust or stop prescription thyroid medicine on your own.

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

Read the full Thyroid Extract monograph & all interactions
Keep checking

Other Drugs & Thyroid Extract

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

0Major
3Moderate
2,019Minor
807No known interaction
3 Moderate 2,019 Minor 807 No interaction
Moderate

3 interactions

Minor

2,019 interactions

Showing 60 of 2,019 minor interactions — see all 2,019 on the Thyroid Extract page.

No interaction 807 drugs checked — show the list

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

Showing the 60 most looked-up of 807 medications checked with no known interaction — see the full Thyroid Extract list.

See the full Thyroid Extract interactions page
See every supplement checked against Tretinoin, Benzoyl Peroxide, ranked by severity
Evidence & sources

Thyroid Extract References

The 6 references that drive our Thyroid Extract 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. Benvenga, S., Trimarchi, F., Barbera, C., Costante, G., Morabito, S., Barberio, G., and Consolo, F. Circulating immunoglobulin E (IgE) antibodies to L-thyroxine in a euthyroid patient with multinodular goiter and allergic rhinitis. J Endocrinol Invest 198 PubMed
  2. Gerard, P., Malvaux, P., and De Visscher, M. Accidental poisoning with thyroid extract treated by exchange transfusion. Arch Dis Child 1972;47(256):981-982. PubMed
  3. Tofahrn, J. and Hundeiker, M. [Nevus eruption following thyroidin with spontaneous involution]. Z Hautkr 1976;51(15):617-620.
  4. Rees-Jones RW, Larsen PR. Triiodothyronine and thyroxine content of desiccated thyroid tablets. Metabolism 1977;26(11):1213-1218. PubMed
  5. Jackson IM, Cobb WE. Why does anyone still use desiccated thyroid USP? Am J Med 1978;64(2):284-8. PubMed
  6. Jha S, Waghdhare S, Reddi R, Bhattacharya P. Thyroid storm due to inappropriate administration of a compounded thyroid hormone preparation successfully treated with plasmapheresis. Thyroid. 2012;22(12):1283-6. 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 Thyroid Extract and Tretinoin, Benzoyl Peroxide Together: Common Questions

Is it safe to take Thyroid Extract with Tretinoin, Benzoyl Peroxide?
We do not list a known interaction between Thyroid Extract and Tretinoin, Benzoyl Peroxide. 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 Thyroid Extract and Tretinoin, Benzoyl Peroxide have any of the same side effects?
Yes — our sources link each of them separately to one 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 Thyroid Extract and Tretinoin, Benzoyl Peroxide combination checked?
Interactions in our licensed database are recorded against drug classes. Tretinoin, Benzoyl Peroxide is filed under 4 classifications, and Thyroid Extract has documented interactions with 2 drug classes — none of Tretinoin, Benzoyl Peroxide'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 Thyroid Extract interact with any other medications?
Yes. Thyroid Extract has 2,022 documented drug interactions in our database — Tretinoin, Benzoyl Peroxide 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 Tretinoin, Benzoyl Peroxide interact with any supplements?
Yes. Tretinoin, Benzoyl Peroxide has documented interactions with 35 supplements in our database — Thyroid Extract is not one of them. The Tretinoin, Benzoyl Peroxide 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

Thyroid Extract monograph Uses, safety profile, and every drug interaction in one place Tretinoin, Benzoyl Peroxide supplement interactions Every supplement checked against Tretinoin, Benzoyl Peroxide, 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 6 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Tretinoin, Benzoyl Peroxide and Thyroid Extract?

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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.