Tirzepatide (Zepbound, Mounjaro): may make the pill less effective because it slows stomach emptying, most after the first dose. Switch to a non-oral method, or add a barrier method, for 4 weeks after starting and 4 weeks after each dose increase.12
Non-oral hormonal methods (patch, ring, implant, injection, hormonal IUD) should not be affected, the label says.1
Semaglutide: in a study of women taking a combined pill, semaglutide did not reduce the pill's bioavailability, and its labels carry no contraception instruction.53
Untested drugs, untested interactions. No research GLP-1 sold online has an interaction study with the pill (our reasoning: none has a label or a published one).
On this page
- What the tirzepatide labels say
- Why it happens: gastric emptying
- Semaglutide and the pill
- Research GLP-1s
- Frequently asked questions
- Related on Grey Peptides
- Sources
What the tirzepatide labels say
The contraception advice sits in section 8.3 of both tirzepatide labels, and again in section 7 (drug interactions). Quoted word for word, with the pharmacokinetic finding from section 12.3 that it rests on:
From the FDA label (quoted word for word from the current US label)
| Product | What the label says | Label section |
|---|---|---|
| Zepbound (tirzepatide) | “Use of ZEPBOUND may reduce the efficacy of oral hormonal contraceptives due to delayed gastric emptying. This delay is largest after the first dose and diminishes over time.” | section 8.31 |
| Zepbound (tirzepatide) | “Advise patients using oral hormonal contraceptives to switch to a non-oral contraceptive method, or add a barrier method of contraception for 4 weeks after initiation with ZEPBOUND and for 4 weeks after each dose escalation” | section 8.31 |
| Zepbound (tirzepatide) | “Hormonal contraceptives that are not administered orally should not be affected” | section 71 |
| Mounjaro (tirzepatide) | “Advise patients using oral hormonal contraceptives to switch to a non-oral contraceptive method or add a barrier method of contraception for 4 weeks after initiation and for 4 weeks after each dose escalation with MOUNJARO” | section 8.32 |
| Zepbound (tirzepatide) | “mean C max of ethinyl estradiol, norgestimate, and norelgestromin was reduced by 59%, 66%, and 55%, while mean AUC was reduced by 20%, 21%, and 23%, respectively.” | section 12.31 |
| Wegovy (semaglutide) | “WEGOVY delays gastric emptying. May impact absorption of concomitantly administered oral medications.” | section 73 |
| Ozempic injection (semaglutide) | “Metformin and oral contraceptive drug (ethinylestradiol/levonorgestrel) were assessed at steady state.” | section 12.34 |
Put plainly: in the label's study, a single dose of tirzepatide cut the peak blood levels of the pill's hormones by more than half and the total exposure by about a fifth, and delayed the peak by a few hours.1 Because the slowing of the stomach is largest after the first dose and fades, the label's window is the four weeks after starting and after each step up.12
Why it happens: gastric emptying
GLP-1 drugs slow how fast the stomach empties. A tablet swallowed while the stomach is emptying slowly reaches the gut, and the blood, later and more spread out. The Wegovy label puts it generally: the drug delays gastric emptying and may affect the absorption of oral medicines taken with it.3 A 2026 review notes that a fall in peak concentration is not the same as a loss of contraceptive effect: the active metabolite's total exposure fell only about a fifth, and nobody has tested whether pregnancies actually increase.6
The label still asks for a back-up method, because a contraceptive failure cannot be undone and the drug's animal data counsel against pregnancy (our reasoning; see the pregnancy page).
Semaglutide and the pill
Semaglutide was tested against a combined pill (ethinylestradiol and levonorgestrel) in 43 postmenopausal women with type 2 diabetes at steady state. The pill's bioavailability was not reduced: ethinylestradiol exposure met the bioequivalence criterion, and levonorgestrel exposure was 20% higher.5 The Ozempic label lists the oral contraceptive among the medicines assessed at steady state.4 Because that study was done at steady state, not in the first weeks, it says less about the start of treatment, when slowing of the stomach is greatest (our reasoning).
A 2026 review for obstetricians singled out tirzepatide's delay in gastric emptying as the reason for the back-up advice, and called for contraception counselling for women of reproductive age on these drugs.7
Research GLP-1s
Retatrutide and other GLP-1-class compounds sold as research chemicals have no label, so there is no contraception section to read and no published interaction study with the pill (our reasoning). Anyone using one while relying on the pill is relying on an untested combination. Our GLP-1 drug interactions guide covers the other oral medicines the labels flag.
Frequently asked questions
Do I need back-up contraception on Zepbound or Mounjaro?
If you use the pill, yes: the labels advise switching to a non-oral method or adding a barrier method for 4 weeks after starting and for 4 weeks after each dose increase.
Does Wegovy or Ozempic affect the pill?
In a steady-state study semaglutide did not reduce the bioavailability of a combined pill, and the semaglutide labels carry no contraception instruction. They do say the drug delays gastric emptying and may affect oral medicines generally.
Is my patch, ring, implant or hormonal IUD affected?
The tirzepatide labels say hormonal contraceptives that are not taken by mouth should not be affected.
Related on Grey Peptides
Sources
Labels are cited by their DailyMed set and version and quoted from the cached text; studies by PMID, checked on PubMed. All read November 3, 2026.
- Zepbound (tirzepatide) US prescribing information (Eli Lilly; DailyMed set 487cd7e7, version 40, effective August 28, 2026), sections 7, 8 and 12. DailyMed
- Mounjaro (tirzepatide) US prescribing information (Eli Lilly; DailyMed set d2d7da5d, version 40, effective August 27, 2026), sections 7, 8 and 12. DailyMed
- Wegovy (semaglutide) US prescribing information (Novo Nordisk; DailyMed set ee06186f, version 19, effective June 18, 2026), sections 7, 8 and 12. DailyMed
- Ozempic injection (semaglutide) US prescribing information (Novo Nordisk; DailyMed set adec4fd2, version 20, effective June 1, 2026), sections 7, 8 and 12. DailyMed
- Kapitza C, Nosek L, Jensen L, et al. Semaglutide, a once-weekly human GLP-1 analog, does not reduce the bioavailability of the combined oral contraceptive, ethinylestradiol/levonorgestrel. J Clin Pharmacol 2015;55(5):497-504. PMID 25475122. Source
- Viana DPDC, Invitti AL, Jacobsen L, Schor E. Tirzepatide and oral progestogens: A hypothesis-generating review of a biologically plausible pharmacokinetic interaction in gynaecologic disease control and menopausal hormone therapy. Maturitas 2026;214:109116. PMID 42721915. Source
- Chauhan I, et al. What obgyns need to know about GLP-1 receptor agonists. Curr Opin Obstet Gynecol 2026;38(5):366-373. PMID 42108205. Source
This section reports what labels, LactMed and published studies say; it is not medical advice, and it does not replace the obstetrician, midwife, prescriber or pharmacist who knows your history. Grey Peptides sells nothing, links to no seller and rates none. If you are pregnant and have taken something you are unsure of, the MotherToBaby service (1-866-626-6847 in the US) answers questions about exposures in pregnancy and breastfeeding.