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HealthRX.com · Printable medication review sheet

St John's wort and Mounjaro: whole-medicine-list check

Mounjaro's label does not mention St John's wort, and it describes tirzepatide being broken down by protein cleavage rather than by the CYP enzymes the herb switches on, so this sheet is about everything else you take by mouth. List each medicine, note when St John's wort started or stopped, and take the sheet to a pharmacist.

Companion to “Can I Take St. John's Wort with Mounjaro (Tirzepatide)?” · healthrx.com/supplements-mounjaro/with-st-johns-wort · Facts checked 2026-10-18

Your St John's wort

Product, extract and amount per tablet (mg)
Tablets per day
Date started, and date stopped if you have
What you take it formood, sleep, something else

Every other medicine and supplement

Include anything taken by mouth, even occasionally.

MedicineDose and timeSwallowed, injected or other routeStarted before or after St John's wort?Pharmacist's note
Mounjaro (tirzepatide)weeklyinjection

Medicines the sources name: tick any you take

  • Birth control pills
  • Warfarin
  • Simvastatin or another statin
  • An antidepressant, including an SSRI or SNRI
  • Seizure medicines such as phenytoin or carbamazepine
  • Digoxin or another heart medicine
  • HIV or transplant medicines

What the label and studies say

  • Mounjaro's label does not mention St John's wort.[1]
  • Mounjaro's label: tirzepatide is metabolized by proteolytic cleavage, and laboratory studies showed low potential for it to inhibit or induce CYP enzymes.[1]
  • Mounjaro's label: if you use oral hormonal birth control, switch to a non-oral method or add a barrier method for 4 weeks after starting and for 4 weeks after each dose increase.[1]
  • NCCIH lists birth control pills, warfarin and certain statins, including simvastatin, among medicines St John's wort can weaken.[2]
  • In 12 healthy volunteers, 14 days of St John's wort shortened alprazolam's half-life from 12.4 to 6.0 hours.[3]
  • After St John's wort was stopped, CYP3A activity returned to its starting level in about 1 week.[4]
  • NCCIH: combined with certain antidepressants or other drugs that affect serotonin, St John's wort may cause serious serotonin-related side effects.[2]

Questions for the pharmacist

  1. Which of my oral medicines does St John's wort affect?
  2. If I stop it, which medicine levels could rise over the following week, and should any be checked?
  3. Do I need backup contraception, and for how long?
  4. Is my antidepressant safe to combine with it?
  5. Should my INR, cholesterol or another level be rechecked?
Sources for the facts on this sheet
  1. Eli Lilly and Company, via DailyMed. Mounjaro (tirzepatide) injection, for subcutaneous use: prescribing information and Medication Guide. Effective 2026-08-27. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d2d7da5d-ad07-4228-955f-cf7e355c8cc0
  2. National Center for Complementary and Integrative Health (NIH). St. John's Wort: Usefulness and Safety. Accessed 2026-10-18. https://www.nccih.nih.gov/health/st-johns-wort
  3. Markowitz JS, Donovan JL, DeVane CL, et al. Effect of St John's wort on drug metabolism by induction of cytochrome P450 3A4 enzyme. JAMA 2003. PMID 13129991. https://pubmed.ncbi.nlm.nih.gov/13129991/
  4. Imai H, Kotegawa T, Tsutsumi K, et al. The recovery time-course of CYP3A after induction by St John's wort administration. Br J Clin Pharmacol 2008. PMID 18294328. https://pubmed.ncbi.nlm.nih.gov/18294328/

This sheet records information for a conversation with your prescriber or pharmacist. It does not replace their instructions or the medication's prescribing information.