Glucagon-like peptide-1 receptor agonists (GLP-1s or GLP-1RAs) are used in the management of obesity and type 2 diabetes. Note that Tirzepatide (Mounjaro) is a dual receptor agonist for GLP-1 and glucose-dependent insulinotropic polypeptide (GIP).
The UK Medicines and Healthcare products Regulation Agency (MRHA) has produced a summary document outlining considerations for both prescribers and patients to consider when taking these medications for weight loss and/or diabetes:
- adverse effects associated with GLP-1s
- some of the most common side effects are gastrointestinal effects such as nausea, vomiting, and diarrhoea
- although infrequent, acute pancreatitis) has been reported with GLP-1s
- GLP-1s and pregnancy and contraception
- all individuals of child-bearing potential (who are able to become pregnant) using GLP-1 medications should take steps to ensure they do not become pregnant
- as a precautionary measure, you should use contraception while taking GLP-1 medicines and for a defined “wash-out” period after (the length of time the medicine should be stopped before trying to get pregnant)
- if taking semaglutide then this should be stopped for at least 2 months before attempting to conceive
- if taking tirzepatide then this should be stopped for at least 1 month before attempting to conceive
- oral contraceptive pill/progestogen only pill (min-pill) and tirzepatide
- if using tirzepatide and taking an oral contraceptive (the pill) then the patient should use a non-oral form of contraception for four weeks after starting, and for four weeks after any increase in dose
- can be a barrier form of contraception (e.g. condom) alongside your pill, or switching to a non-oral contraceptive like the coil or implant
- tirzepatide may reduce the effectiveness of oral contraceptives in those who are overweight or obese
- note that is currently no evidence that semaglutide, exenatide, liraglutide, dulaglutide or lixisenatide reduce the effectiveness of oral contraception (i.e. the combined pill, or the progestogen only pill/ “mini-pill”)
- GLP-1 medicines should not be taken by people who are breastfeeding
Summary: What do those taking or planning to take these medicines need to remember (1)
- You should only take GLP-1 medicines if they have been prescribed to you by a healthcare professional
- Always have a conversation with your prescriber about the benefits and risks of GLP-1 medicines before you start taking them
- Do not take GLP-1 medicines if you are pregnant, trying to get pregnant or breastfeeding. If you get pregnant while using them, talk to a healthcare professional straight away
- If you are prescribed Mounjaro (tirzepatide), and you are using an oral contraceptive (the pill), use a non-oral form (such as condoms, the coil, or implant) of contraception in addition to your pill for four weeks after starting GLP-1 medicines, and for four weeks after any increase in dose
- Understand the potential side effects and have a conversation with a healthcare professional if you are concerned
- Tell your doctor you take a GLP-1 medicine if you are about to have surgery
- Report any adverse reactions to the Yellow Card scheme
- After taking the recommended four doses in your syringe, any medicine left in the syringe should not be extracted and should be disposed of in the bin
- Use of these medicines is not a quick fix to lose weight and the MHRA has not assessed the safety and effectiveness of these medicines when used by people who do not meet the medical requirements
Reference:
- MHRA (June 5th 2025). GLP-1 medicines for weight loss and diabetes: what you need to know