GLP-1 agonists (weight loss injections) and contraception or HRT
The GLP-1 agonist medications may interact with contraceptive methods and HRT.
What are GLP-1 agonists?
GLP-1 agonists include medications such as Mounjaro (tirzepatide), Ozempic or Wegovy (semaglutide) and others. They may be prescribed to treat type two diabetes, or to facilitate weight loss.
One of the main ways they work is by slowing the rate at which food leaves the stomach (delayed gastric emptying). This may reduce the absorption of oral medications.
Interaction with HRT
The British Menopause Society has issued guidelines for women on GLP-1 medications. This applies to both tirzepatide (Mounjaro) and semaglutide (Ozempic, Wegovy).
Oestrogen
Transdermal oestrogen (gel, patch or spray) is preferred if you are using a GLP-1 agonist, also, if you are overweight or obese. There are no interactions with transdermal HRT.
If you take oestrogen tablets, you may need to switch to a transdermal route.
Progestogen
If you take oral progestogen as part of your HRT (e.g. utrogestan, norethisterone, medroxyprogesterone), you should know that tirzepatide and semaglutide might reduce the effectiveness in protecting the endometrium (womb lining). Progestogen is important to protect your womb lining if you are taking oestrogen. If the absorption of progestogen is reduced, your womb lining could increase, which can cause abnormal bleeding or even endometrial cancer.
Please contact the practice to book an HRT review.
Switching to a non-oral form of progestogen (combined patch, hormone-releasing coil) is preferable while the GLP-1 agonist is being used.
If you stay on oral progesterone (e.g. Utrogestan), the dose should be increased:
After starting or increasing the dose of tirzepatide or semaglutide, you should double your progesterone dose for 4 weeks.
If you do not take your HRT orally (e.g., you use a patch, hormonal coil or vaginal tablet) there are no interactions and you don’t need to worry.
Leaflet
BMS -Use of incretin-based therapies in women using hormone replacement therapy (PDF)