Weight loss injections and oral contraception: What you need to know
Most weight loss injection in the UK are a kind of drug called GLP-1 agonists. We know them better by their brand names.
Some common ones include:
- Mounjaro (Tirzepatide)
- Ozempic, Wegovy & Rybelsus (Semaglutide)
- Bydureon BCise (Exenatide)
- Saxenda Diavic & Victoza (Liraglutide)
- Trulicity (Dulaglutide)
- Suliqua (contains Lixisenatide)
I'm on the pill. Will this affect it?
If you're on Mounjaro yes, it could affect your pill. You need to use an extra barrier method (like condoms) for four weeks after starting on Mounjaro and for four weeks after any dose increase. So you might want to think about switching to a non-oral method (like the implant, coil, or injection) while you're on Mounjaro.
If you're on the others listed: There's no evidence yet that they make the pill less effective.
What if I have a dodgy tummy (diarrhoea or vomiting)?
Being sick or having diarrhoea is are common side effects of these meds, and can stop your pill from working properly.
- If you're sick within 3 hours of taking your pill.
- If you have really bad diarrhoea that lasts for more than 24 hours.
…then you need to follow the usual "missed pill" advice. There’s a missed pill calculator here.
If it keeps happening, think about using condoms as well or changing to a contraception that isn't affected by tummy troubles, like an implant or coil.
What about non-pill contraception, like the coil, implant, or injection?
No worries at all! There's no reason to think GLP-1 agonists affect methods that aren't taken by mouth. So, the coil, implant, injection, patch, or ring are all perfectly fine to use with these medications.
I'm switching to a different GLP-1. Does the advice change?
The key thing is if you are switching to Mounjaro from any other GLP-1, then you need to use condoms as well as your pill for four weeks after the switch and after any dose increase if you don’t want to become pregnant.
What if I need the morning-after pill?
We don't know yet if GLP-1s affect the emergency contraceptive pill. Because of this, the copper coil (IUD) is your best bet. It's the most effective form of emergency contraception and isn't affected by any medication, or by vomiting. Always tell the doctor, nurse or pharmacist giving you emergency contraception about all the medicines you're taking.
Can I use them when I’m pregnant or planning to be?
It's really important to use effective contraception while on these drugs, as you shouldn't take them during pregnancy. If you find out you're pregnant while taking one, speak to your doctor straight away.
You should also plan to come off the medication a good while before you try to get pregnant. The recommended "washout" period is different for each drug. Here are some examples:
- Mounjaro (Tirzepatide) - one month
- Ozempic, Wegovy & Rybelsus (Semaglutide) - two months
- Bydureon BCise (Exenatide) - 12 weeks
For more detailed information, visit College of Sexual and Reproductive Healthcare's (CoSRH) website