How weight-loss injections affect your HRT and Contraception
If you are currently taking, or considering starting, a weight loss injection, it is important to understand how it might interact with your other medications.
Medicines such as Mounjaro (tirzepatide), Wegovy, Ozempic (semaglutide), and Saxenda (liraglutide) all belong to a similar class of drugs. While they are highly effective for weight management, they can alter how your body absorbs certain oral medications, including oral contraception and oral Hormone Replacement Therapy (HRT).
Why Does This Happen?
Weight loss injections work partly by slowing down the speed at which your stomach empties its contents into your intestines.
Because oral medications need to reach your intestines to be properly absorbed into your bloodstream, this delay means that pills can take longer to be absorbed. In some cases, the full dose may not be absorbed effectively at all.
What This Means for Your Contraception
If you take an oral contraceptive pill (the combined pill or the progestogen-only “mini pill”), a weight loss injection could make it less effective, increasing your risk of an unplanned pregnancy.
What you should do:
Consider a switch: The most reliable option is to switch to a non-oral method of contraception. These bypass the digestive system entirely. Excellent alternatives include the contraceptive implant, injection, hormonal coil (IUS), copper coil (IUD), vaginal ring, or contraceptive patches.
Use extra precautions: If you wish to stay on the pill, you should use an additional barrier method (such as condoms) when you first start the weight loss injection and for four weeks every time your injection dose is increased.
What This Means for Your HRT
If you take HRT in tablet form, the delayed absorption caused by weight loss injections can lead to fluctuating hormone levels. This means you might experience a sudden return of menopause symptoms, such as hot flushes, mood changes, or poor sleep.
What you should do:
- Switch to transdermal HRT: Speak to us about switching your oral HRT to a transdermal method. Transdermal HRT is absorbed directly through the skin into the bloodstream. Options include HRT patches or gels.
- Monitor your symptoms: If you are already on transdermal HRT, your symptom control should not be affected by weight loss injections. However, as you lose weight, your hormone needs may change naturally, so keep track of your symptoms.
Planning a Pregnancy
These medications must not be taken if you are pregnant or trying to conceive. Because the drug stays in your system for a long time, you must stop taking it well in advance.
Wegovy/Ozempic (Semaglutide): Stop at least 2 months before trying to conceive.
Mounjaro (Tirzepatide): Stop at least 1 month before trying to conceive.
Your health and safety are our priority. If you are taking any of these weight loss injections—whether prescribed by us or a private clinic—please let us know.
Disclaimer: This guidance is based on current recommendations from the NHS, the Faculty of Sexual and Reproductive Healthcare (FSRH), and the British Menopause Society. Advice may change as new evidence emerges.