Drug & supplement interaction

Spearmint + Levothyroxine, Liothyronine

Levothyroxine, Liothyronine brand name: Armour Thyroid.

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 Spearmint and Levothyroxine, Liothyronine 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

Spearmint and Levothyroxine, Liothyronine

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, Liothyronine and Spearmint 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.

Spearmint safety at a glance

Spearmint overall Use caution Generally safe as food or tea, but concentrated supplements and oils need more caution.
Pregnancy Likely Safe When used in the amounts commonly found in foods. Read the full pregnancy detail
Breastfeeding Likely Safe When used in the amounts commonly found in foods. There is insufficient reliable information available about the safety of spearmint during lactation. Avoid usi... 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, Liothyronine and Spearmint? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Levothyroxine, Liothyronine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Levothyroxine, Liothyronine is filed under 3 classifications — including thyroid hormone, oral drugs. Spearmint has documented interactions with 2 drug classes — the most serious being cns depressants (moderate) and hepatotoxic drugs (moderate) — and none of Levothyroxine, Liothyronine’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

Spearmint Does Interact With Other Medications

Spearmint has 579 moderate known drug interactions in our database — Levothyroxine, Liothyronine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 579 No known interaction 2,251 (incl. Levothyroxine, Liothyronine)
Taking anything else?

Check Another of Your Medications Against Spearmint

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

What to actually watch for

What Spearmint Itself Has Been Linked To

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

  • Increased appetite / Weight gain Additional detail

    “Orally, taking spearmint extract 600 mg daily has been associated with one report of increased appetite and weight gain in one clinical trial. However, it is not certain that these adverse events were caused by spearmint extract.”

    Spearmint · Natural Medicines adverse-effect record, reported in myasthenia gravis.

    1 source cited
    1. 94925. Lasrado JA, Nieman KM, Fonseca BA, et al. Safety and tolerability of a dried aqueous spearmint extract. Regul Toxicol Pharmacol 2017;86:167-176. PubMed
  • Bloating or gas / Dry mouth / Stomach upset / Constipation / Diarrhea Additional detail

    “Orally, taking spearmint extract 600 mg daily has been associated with dyspepsia in one clinical trial. Taking a higher dose of 900 mg daily has been associated with diarrhea and belching. Drinking 2 cups of spearmint tea with normal amounts of rosmarinic acid has been associated with one report of dry mouth in clinical research.”

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

    3 sources cited
    1. 94925. Lasrado JA, Nieman KM, Fonseca BA, et al. Safety and tolerability of a dried aqueous spearmint extract. Regul Toxicol Pharmacol 2017;86:167-176. PubMed
    2. 94923. Connelly AE, Tucker AJ, Tulk H, et al. High-rosmarinic acid spearmint tea in the management of knee osteoarthritis symptoms. J Med Food 2014;17:1361-7. PubMed
    3. 75700. Bulat, R., Fachnie, E., Chauhan, U., Chen, Y., and Tougas, G. Lack of effect of spearmint on lower oesophageal sphincter function and acid reflux in healthy volunteers. Aliment.Pharmacol Ther. 1999;13(6):805-812. PubMed
  • A fast or pounding heartbeat Additional detail

    “Orally, taking spearmint extract 600 mg daily has been associated with one report of tachycardia in one clinical trial. However, it is not certain that this adverse event was caused by spearmint extract.”

    Spearmint · Natural Medicines adverse-effect record, reported in myasthenia gravis.

    1 source cited
    1. 94925. Lasrado JA, Nieman KM, Fonseca BA, et al. Safety and tolerability of a dried aqueous spearmint extract. Regul Toxicol Pharmacol 2017;86:167-176. PubMed
  • Anxiety or restlessness Additional detail

    “Orally, taking spearmint extract 600 mg daily has been associated with one report of anxiety in one clinical trial. However, it is not certain that this adverse event was caused by spearmint extract.”

    Spearmint · Natural Medicines adverse-effect record, reported in anxiety.

    1 source cited
    1. 94925. Lasrado JA, Nieman KM, Fonseca BA, et al. Safety and tolerability of a dried aqueous spearmint extract. Regul Toxicol Pharmacol 2017;86:167-176. PubMed
  • Swelling Additional detail

    “Topically, spearmint oil and leaves have caused allergic dermatitis. Allergic contact cheilitis has also occurred from spearmint oil in toothpaste or chewing gum. Spearmint oil inhalation has also caused allergic dermatitis. Orally, spearmint leaves have caused allergy-associated swelling of the soft palate. A specific 50 KDa protein in the spearmint was found to be the responsible allergen.”

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

    6 sources cited
    1. 75711. Bonamonte, D., Mundo, L., Daddabbo, M., and Foti, C. Allergic contact dermatitis from Mentha spicata (spearmint). Contact Dermatitis 2001;45(5):298.
    2. 75731. Tomson, N., Murdoch, S., and Finch, T. M. The dangers of making mint sauce. Contact Dermatitis 2004;51(2):92-93. PubMed
    3. 75737. Clayton, R. and Orton, D. Contact allergy to spearmint oil in a patient with oral lichen planus. Contact Dermatitis 2004;51(5-6):314-315. PubMed
    4. 31403. Poon, T. S. and Freeman, S. Cheilitis caused by contact allergy to anethole in spearmint flavoured toothpaste. Australas.J Dermatol. 2006;47(4):300-301. PubMed
    5. 31528. Andersen, K. E. Contact allergy to toothpaste flavors. Contact Dermatitis 1978;4(4):195-198. PubMed
    6. 75706. Francalanci, S., Sertoli, A., Giorgini, S., Pigatto, P., Santucci, B., and Valsecchi, R. Multicentre study of allergic contact cheilitis from toothpastes. Contact Dermatitis 2000;43(4):216-222. 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 Spearmint — expand a row for the licensed statement it rests on. We haven’t matched Levothyroxine, Liothyronine 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 Levothyroxine, Liothyronine.

Special populations

Spearmint in Pregnancy & Breastfeeding

Pregnancy Likely Safe

When used in the amounts commonly found in foods.

Pregnancy Possibly Unsafe

When used orally during pregnancy in excessive amounts. Animal research suggests that spearmint tea may cause uterine damage. Avoid using in amounts greater than those typically found in foods during pregnancy.

Lactation Likely Safe

When used in the amounts commonly found in foods. There is insufficient reliable information available about the safety of spearmint during lactation. Avoid using in amounts greater than those typically found in foods.

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 Levothyroxine, Liothyronine

This page covers Spearmint only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levothyroxine, Liothyronine 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, Liothyronine page

“For anyone taking levothyroxine or liothyronine (Armour Thyroid), this list earns real caution, not just a passing glance. Most of these 50 ingredients pull in one of two directions.”

Reviewed by 2 · Jul 18, 2026

Open the Levothyroxine, Liothyronine interaction page

One more smart check

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

We hold 408 real supplement products containing Spearmint, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Spearmint. Even though Spearmint itself has no known interaction with Levothyroxine, Liothyronine, 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 Spearmint and Levothyroxine, Liothyronine 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 Spearmint
Top 25%

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

29 days ago today
Medication Levothyroxine, Liothyronine
Top 5%

#61 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 Spearmint reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Spearmint and Levothyroxine, Liothyronine 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 Spearmint

What is Spearmint?

Spearmint
  • Digestive upset and indigestion
  • Nausea
  • Hormonal acne and unwanted hair (PCOS-related)
  • Memory and focus
  • Mild stress and anxiety
  • Joint discomfort

Spearmint is a common culinary mint that is generally safe in food and tea amounts. Early research suggests possible benefits for digestion, mild hormone-related issues (such as excess facial hair in women), and memory, but the evidence is still limited. Talk to your pharmacist or doctor before using concentrated supplements, especially if you are pregnant or have a health condition.

Mentha spicata · Lamiaceae · Leaves and essential oil · Tea, capsules, dried leaf, essential oil, extract

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

Spearmint: dosing

There is no official standard dose for spearmint. In research, people have used it as a cup of tea once or twice a day, or as standardized extracts in capsules. Because products vary widely in strength, it is best to follow the directions on the product label.Spearmint supplements are sometimes standardized to a certain amount of rosmarinic acid. Start low and watch how your body responds.

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

Read the full Spearmint monograph & all interactions
Medication

About Levothyroxine, Liothyronine

Most-Reported Side Effects for Levothyroxine, Liothyronine

From FAERS, the FDA’s public side-effect reporting system (15 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 4 reports
Asthenia 3 reports
Dizziness 3 reports
Arthralgia 2 reports
Disorientation 2 reports
Keep checking

Other Drugs & Spearmint

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

0Major
579Moderate
0Minor
2,250No known interaction
579 Moderate 2,250 No interaction
Moderate

579 interactions

Showing 60 of 579 moderate interactions — see all 579 on the Spearmint page.

No interaction 2,250 drugs checked — show the list

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

Showing the 60 most looked-up of 2,250 medications checked with no known interaction — see the full Spearmint list.

See the full Spearmint interactions page
See every supplement checked against Levothyroxine, Liothyronine, ranked by severity
Evidence & sources

Spearmint References

The 20 references that drive our Spearmint 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. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  2. Akdogan M, Ozguner M, Aydin G, Gokalp O. Investigation of biochemical and histopathological effects of Mentha piperita Labiatae and Mentha spicata Labiatae on liver tissue in rats. Hum Exp Toxicol 2004;23:21-8.
  3. Poon, T. S. and Freeman, S. Cheilitis caused by contact allergy to anethole in spearmint flavoured toothpaste. Australas.J Dermatol. 2006;47(4):300-301. PubMed
  4. Andersen, K. E. Contact allergy to toothpaste flavors. Contact Dermatitis 1978;4(4):195-198. PubMed
  5. de Sousa, D. P., Farias Nobrega, F. F., and de Almeida, R. N. Influence of the chirality of (R)-(-)- and (S)-(+)-carvone in the central nervous system: a comparative study. Chirality 5-5-2007;19(4):264-268.
  6. Larsen, W., Nakayama, H., Fischer, T., Elsner, P., Frosch, P., Burrows, D., Jordan, W., Shaw, S., Wilkinson, J., Marks, J., Jr., Sugawara, M., Nethercott, M., and Nethercott, J. Fragrance contact dermatitis: a worldwide multicenter investigation (Part II PubMed
  7. Guney, M., Oral, B., Karahanli, N., Mungan, T., and Akdogan, M. The effect of Mentha spicata Labiatae on uterine tissue in rats. Toxicol.Ind.Health 2006;22(8):343-348.
  8. Masumoto, Y., Morinushi, T., Kawasaki, H., Ogura, T., and Takigawa, M. Effects of three principal constituents in chewing gum on electroencephalographic activity. Psychiatry Clin.Neurosci. 1999;53(1):17-23. PubMed
  9. Bulat, R., Fachnie, E., Chauhan, U., Chen, Y., and Tougas, G. Lack of effect of spearmint on lower oesophageal sphincter function and acid reflux in healthy volunteers. Aliment.Pharmacol Ther. 1999;13(6):805-812. PubMed
  10. Francalanci, S., Sertoli, A., Giorgini, S., Pigatto, P., Santucci, B., and Valsecchi, R. Multicentre study of allergic contact cheilitis from toothpastes. Contact Dermatitis 2000;43(4):216-222. PubMed
  11. Bonamonte, D., Mundo, L., Daddabbo, M., and Foti, C. Allergic contact dermatitis from Mentha spicata (spearmint). Contact Dermatitis 2001;45(5):298.
  12. Tomson, N., Murdoch, S., and Finch, T. M. The dangers of making mint sauce. Contact Dermatitis 2004;51(2):92-93. PubMed
  13. Clayton, R. and Orton, D. Contact allergy to spearmint oil in a patient with oral lichen planus. Contact Dermatitis 2004;51(5-6):314-315. PubMed
  14. Dal Sacco, D., Gibelli, D., and Gallo, R. Contact allergy in the burning mouth syndrome: a retrospective study on 38 patients. Acta Derm.Venereol. 2005;85(1):63-64. PubMed
  15. Goncalves, J. C., Oliveira, Fde S., Benedito, R. B., de Sousa, D. P., de Almeida, R. N., and de Araujo, D. A. Antinociceptive activity of (-)-carvone: evidence of association with decreased peripheral nerve excitability. Biol Pharm Bull. 2008;31(5):1017- 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 Spearmint and Levothyroxine, Liothyronine Together: Common Questions

Is it safe to take Spearmint with Levothyroxine, Liothyronine?
We do not list a known interaction between Spearmint and Levothyroxine, Liothyronine. 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 Spearmint and Levothyroxine, Liothyronine combination checked?
Interactions in our licensed database are recorded against drug classes. Levothyroxine, Liothyronine is filed under 3 classifications, and Spearmint has documented interactions with 2 drug classes — none of Levothyroxine, Liothyronine'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 Spearmint interact with any other medications?
Yes. Spearmint has 579 documented drug interactions in our database — Levothyroxine, Liothyronine 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, Liothyronine interact with any supplements?
Yes. Levothyroxine, Liothyronine has documented interactions with 50 supplements in our database — Spearmint is not one of them. The Levothyroxine, Liothyronine 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

Spearmint monograph Uses, safety profile, and every drug interaction in one place Levothyroxine, Liothyronine supplement interactions Every supplement checked against Levothyroxine, Liothyronine, 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 20 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine, Liothyronine and Spearmint?

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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.