Mounjaro (tirzepatide) is FDA-approved for type 2 diabetes, not weight loss. For weight management, the same molecule is available as Zepbound, which is FDA-approved for chronic weight management. At PEAK, we prescribe Zepbound for weight-loss patients.
The Bottom Line
Mounjaro (tirzepatide) should be stopped at least 2 months before attempting to conceive. Not recommended during pregnancy or breastfeeding. This applies to both Mounjaro and Zepbound.
Why Tirzepatide Is Not Safe in Pregnancy
Animal studies showed embryo-fetal toxicity with tirzepatide at clinically relevant doses. While human data is limited, the concerning animal findings led to a clear prescribing information warning recommending discontinuation before conception.
- Reduced fetal growth and skeletal variations observed in animal studies
- Mechanism may relate to reduced maternal nutrition and/or direct fetal effects
- No adequate human pregnancy studies exist
If You Discover You’re Pregnant
- Stop the medication immediately and contact your provider
- Don’t panic—early exposure doesn’t automatically mean harm
- Your provider will discuss monitoring options
The 2-Month Washout Period
Eli Lilly recommends stopping tirzepatide at least 2 months before planned conception:
- Tirzepatide half-life is approximately 5 days
- Near-complete clearance takes 5–7 half-lives (~5–7 weeks)
- The 2-month recommendation provides a safety margin
The 2-month washout is a minimum. Discuss timing with your provider 3–6 months before you want to start trying to conceive.
Tirzepatide and Fertility
Weight loss from tirzepatide can significantly improve reproductive health:
- Improved ovulation as hormonal balance restores with weight loss
- PCOS improvement—insulin resistance and androgen levels decrease
- Better pregnancy outcomes—lower starting weight reduces gestational risks
Contraception warning: Weight loss can unexpectedly restore fertility. Use reliable contraception during treatment and through the 2-month washout period unless actively planning pregnancy.
Planning for Pregnancy
- Discuss timing 3–6 months before target conception date
- Maximize weight loss and metabolic health while on medication
- Stop tirzepatide at least 2 months before trying to conceive
- Transition to pregnancy-safe weight management strategies
- Use reliable contraception until washout is complete
- Expect some weight regain after stopping
Tirzepatide and Breastfeeding
Safety during breastfeeding is unknown. Most providers recommend waiting until breastfeeding is complete before restarting tirzepatide.
Boxed warning — thyroid C-cell tumors: GLP-1 receptor agonists (semaglutide, tirzepatide, liraglutide) carry an FDA boxed warning for thyroid C-cell tumors observed in rodent studies. They are contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2). Tell your provider immediately if you notice a lump in your neck, difficulty swallowing, or persistent hoarseness.
