Rare but Serious Risks, and When to Get Help?

Uncommon doesn't mean ignorable. The serious risks to know, who shouldn't take these medicines, and the red flags that mean 'get checked'.

Key takeaways

• Serious risks are rare but real — which is why these are prescription-only.
• Severe, persistent tummy pain needs urgent attention.
• Some people shouldn't take them at all.
• When in doubt, contact a clinician or NHS 111.

Most people never meet the serious risks — but knowing them is exactly why a prescriber oversees these medicines. This isn't a page to frighten you; it's a page to help you recognise the rare moments that genuinely warrant a phone call.

Keep the proportion in mind as you read. The everyday effects covered in Common Side Effects and Practical Ways to Settle Them are the ones almost everyone notices, and they're usually mild. The risks below are far less common — but because they can be more serious, it's worth knowing the warning signs so you can act early if they ever appear.

The rarer, serious risks

• Inflammation of the pancreas (pancreatitis) — typically signalled by severe, persistent tummy pain, often felt high in the abdomen and sometimes spreading to the back, which may come with vomiting. This needs urgent attention.
• Gallbladder problems — such as gallstones or inflammation, which can cause pain in the upper-right tummy, nausea, or yellowing of the skin or eyes.
• Dehydration — heavy or prolonged vomiting or diarrhoea can leave you short of fluids, which in some people can in turn affect the kidneys.
• Low blood sugar (hypoglycaemia) — uncommon with a GLP-1 on its own, but more of a consideration when it's taken alongside insulin or sulfonylureas, where a prescriber may review those medicines.
• A thyroid caution linked to findings in animal studies, so these medicines are generally avoided by people with a personal or family history of certain thyroid cancers (medullary thyroid carcinoma) or the inherited condition MEN 2.
• Serious allergic reactions — rare, but signs such as swelling of the face, lips or throat, or difficulty breathing, are a medical emergency.

Some people shouldn't take them at all

These medicines aren't suitable for everyone. They are generally avoided during pregnancy and while breastfeeding, and in people with the thyroid history noted above; a prescriber will also weigh up a past episode of pancreatitis, certain digestive conditions, and the other medicines you take. Only a clinician who knows your full history can judge whether one is appropriate for you.

If you could become pregnant, it's worth discussing contraception and timing with your prescriber, since these medicines are not recommended in pregnancy and planning ahead matters.

The red flags worth remembering

You don't need to track every possibility — just a short mental list of signs that mean 'get this checked, don't wait it out'. Severe or persistent tummy pain, especially if it spreads to your back or comes with vomiting. Signs of dehydration such as feeling very thirsty, dizzy, or passing little urine after a spell of vomiting or diarrhoea. Yellowing of the skin or eyes. Any sign of a serious allergic reaction. And, if you take insulin or a sulfonylurea, the usual symptoms of a hypo — shakiness, sweating, confusion.

Trust your own sense of things, too. If a symptom feels severe, frightening, or simply unlike normal settling-in, that's reason enough to seek advice — you don't need to be certain it's serious first.

Who to contact, and when

For non-urgent worries, a pharmacist or your GP practice can usually help quickly. If something feels urgent but you're not sure where to turn, NHS 111 is there day and night to point you to the right care. For anything that looks like a medical emergency — severe unrelenting pain, breathing difficulty, or collapse — call 999 or go to A&E.

When to get help Seek prompt advice for severe stomach pain, signs of an allergic reaction, signs of dehydration, or any symptom that worries you. If it's urgent and you're unsure where to turn, NHS 111 can help; for an emergency, call 999.

Sources

• MHRA
• manufacturer prescribing information
• NICE
• NHS