Guide · Safety · 3 min read

Contraception, pregnancy and breastfeeding

By the CalJab team, with sources · Last reviewed October 21, 2026

Anyone who can become pregnant and uses a GLP-1 medicine is advised to take steps not to become pregnant. ^1·2·3 These medicines are not used in pregnancy or while trying to get pregnant, because there is not enough safety data to know whether they can harm the baby. ¹

If you are planning a pregnancy

The medicine needs to be stopped before you start trying, and how long depends on the medicine. ¹

• Semaglutide (Wegovy, Ozempic, Rybelsus): at least 2 months before. ^1·2
• Tirzepatide (Mounjaro): at least 1 month before. ^1·3

Keep using contraception during this time too, or avoid sex where you could become pregnant. ¹ Talk to your doctor before making any change to your medicine. ¹

If you become pregnant

If you think you might be pregnant, speak to a healthcare professional straight away. ¹ According to the leaflets, the medicine is stopped when a pregnancy is recognized. ^2·3·4

If you take the pill

• If you use Mounjaro: the MHRA and the US prescribing information advise adding a barrier method such as a condom for 4 weeks after starting and for 4 weeks after each dose increase, or switching to a non-oral method such as a coil or implant. ^1·4·5
• Why: the medicine slows stomach emptying, which can make the pill less effective; this effect is largest after the first dose and fades over time. ⁴
• The European leaflet, however, does not consider Mounjaro's effect on the pill clinically relevant. ³
• For semaglutide, the European leaflet does not expect the pill to become less effective. ²
• Hormonal methods that are not taken by mouth should not be affected. ^1·4

Not every method works straight away; talk to a healthcare professional about which option suits you. ¹

If you are breastfeeding

The MHRA advises that GLP-1 medicines should not be taken while breastfeeding, and the European Wegovy leaflet also says not to use it if you are breastfeeding. ^1·2 The European Mounjaro leaflet, on the other hand, says the medicine passes into breast milk in very low amounts and is not expected to be absorbed by the baby. ³ If you are breastfeeding or planning to, talk to your doctor before starting or continuing the medicine. ³

In CalJab

Your dose history shows the day you moved to a new dose, so you can count the 4 weeks from there. Add the questions you want to ask to your doctor report.

Make decisions about contraception and pregnancy with your doctor.

Written by the CalJab team, with sources. It does not replace your doctor's advice. Found a mistake? Write to support@caljab.app.