Injectable weight loss drugs, contraception and HRT

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Weight loss medications such as Mounjaro (Tirzepatide) and Ozempic, Wegovy and Rybelsus (Semaglutide) work by slowing down how your stomach empties, which can affect how well other medicines (including your contraceptive pill and HRT tablets) are absorbed by your body. Newly released clinical guidance has highlighted safety concerns regarding the combined use of these treatments.

Injectable weight loss drugs and the contraceptive pill

If you take Mounjaro (Tirzepatide), weight moss medication may reduce how well your contraceptive pill is absorbed.

You should:

  • Use a non-oral method of contraception (eg. coil or implant), or
  • Add a barrier method (such as condoms) for 4 weeks after starting or increasing the dose.

Use extra protection (like condoms) if you have vomiting or diarrhoea and follow the missed pill rules in your pill patient information leaflet if you vomit within 3 hours of taking the pill or have diarrhoea for more than 24 hours.

Ozempic, Wegovy and Rybelsus (Semaglutide) do not appear to reduce the effectiveness of the pill.

Injectable weight loss drugs and HRT

If your HRT includes progesterone tablets like Utrogestan, Norethisterone or Medroxyprogestone acetate (also called Provera), there is some concern that weight loss medication may reduce how well your HRT tablet is absorbed. This could lead to irregular bleeding and may affect the protection of your womb lining (potentially leading to an increased risk of endometrial cancer).

Other options are available for your HRT:

  • Mirena Coil (IUS) – Progestrone cover for HRT for up to 5 years and a contraceptive for 8 years.
  • Combined HRT patch – Can contain both hormones (oestrogen and progestogen) and bypasses the stomach.
  • Increase oral progesterone dose – Your clinician or private specialist may recommend a higher dose for 4 weeks after starting or increasing the dose of your weight loss medication.
  • Using progesterone oral capsules vaginally – Not licensed but is commonly used in other cases. You can start using this if already prescribed.