GLP-1 medicines: What you need to know
Glucagon-like peptide-1 receptor agonists (GLP-1s or GLP-1RAs) are medicines that help people feel fuller by mimicking a natural hormone released after eating. Some newer medicines, like Mounjaro, also act on a second hormone involved in appetite and blood sugar control. You may see them referred to in the media as “weight loss injections” or “skinny jabs” but not all of these medicines are authorised for weight loss.
GLP-1s are medicines licensed to treat specific medical disorders and should only be used if you are overweight or diabetic, and not if you want to lose weight for aesthetic or cosmetic purposes.
All GLP-1 medicines are prescription only medicines, which means they can only be prescribed by a healthcare professional.
The only way to guarantee you receive a genuine GLP-1 medicine is to obtain it from a legitimate pharmacy with a prescription issued by a healthcare professional.
Switching between GLP-1 medicines
Before switching from one GLP-1 medicine to another, including between brands containing the same type of GLP-1, you should consult a healthcare professional for advice. GLP-1 medicines vary in how strong they are, how they are used and the types of conditions they can be used for. Switching without medical advice may increase the risk of experiencing side effects or make the treatment less effective.
Risks of taking GLP-1 medicines
Like all medicines, GLP-1 medicines can cause side effects. Some of the most common side effects are gastrointestinal effects such as nausea, vomiting, and diarrhoea. These side effects were observed in clinical trials for these products and make up the majority of the Yellow Card reports the MHRA receives for these products. Most side effects are mild to moderate in severity or short in duration. However, some (such as nausea, vomiting and diarrhoea) sometimes lead to more serious complications such as severe dehydration, resulting in the need to go to hospital.
Although infrequent, inflammation of the pancreas (known as acute pancreatitis) has been reported with GLP-1 medicines and there have been rare reports of pancreatitis with serious or fatal outcomes. The main symptom of this is severe pain in the stomach that radiates to the back and does not go away. Anyone who experiences this should seek urgent medical help.
Semaglutide treatment has, in very rare reports, been linked to a serious eye condition called Non-arteritic anterior ischemic optic neuropathy (NAION), which can affect vision. Anyone treated with semaglutide who notices a change in their eyesight, such as sudden blindness or a rapid deterioration in eyesight should urgently contact a doctor.
GLP-1 medicines, contraception and pregnancy
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.
GLP-1 medicines should not be taken during pregnancy or just before trying to get pregnant. This is because there is not enough safety data to know whether taking a GLP-1 medicine can cause harm to the baby. In some animal studies, GLP-1 medicines were found to be harmful to the unborn foetus, although more information is needed to see whether or not this same effect would be seen in humans. If you are using a GLP-1 medicine and think you might be pregnant, speak to a healthcare professional straight away.
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 you are using Mounjaro (tirzepatide) and take an oral contraceptive (the pill), you should add a non-oral, barrier form of contraception (e.g. condom) for four weeks after starting GLP-1 medicines, and for four weeks after any increase in dose. This is because GLP-1 medicines may reduce the effectiveness of oral contraceptives in those who are overweight or obese. Alternatively, you may wish to switch to a non-oral form of contraception, like the coil or implant which are not as affected by GLP-1s. Not all methods of birth control become effective immediately, please discuss your chosen method with a healthcare professional or consult the patient information leaflet to ensure you are effectively covered.
GLP-1 medicines and breastfeeding
GLP-1 medicines should not be taken by people who are breastfeeding. This is because there is not enough safety data to know whether taking a GLP-1 medicine can cause harm to the baby. If you have any concerns, speak to a healthcare professional.
GLP-1 medicines and depression or suicidal thoughts
Following a comprehensive safety review, it was concluded that the available data does not support a causal association between GLP-1 medicines and depression, suicidal ideation and suicide.
Using GLP-1 medicines around the time of a surgery or an operation
If you are taking a GLP-1 medicine, make sure you inform your healthcare team including the anaesthetist about this prior to your surgical procedure.
This medicine slows the emptying of your stomach, increasing the risk that stomach contents (e.g. food and drink) could enter into your airways and lungs during surgery or procedures whilst you are under general anaesthesia or deep sedation. This means that a modification to the pre-procedure instruction and anaesthetic technique may be required.
Continue to take your prescribed medicine(s) as usual and do not stop your treatment without first discussing this with your doctor. - Source: UK Medicines & Healthcare products Regulatory Authority
