Side effects of GLP-1 treatment: what's common and what helps
Most side effects affect the gut and ease over time. An overview of what's typical, what you can do yourself and when you need help straight away.
- GLP-1
- side effects
- overview
In short
Whether semaglutide, tirzepatide or liraglutide: the most common side effects are similar across GLP-1 medicines. They mainly affect the gut and usually appear in the first weeks and after a dose increase.
A lot can be eased with small changes to daily habits. Some rare symptoms, though, need medical help straight away. You'll find them below. Whether and how a switch or a dose change happens is decided by the doctor in each individual case.
Why the stomach in particular reacts
GLP-1 medicines slow stomach emptying. Food stays in the stomach longer and you feel full sooner. That same effect explains the typical complaints: eat as you used to, and your stomach quickly has too much in it.
That's why the dose is increased slowly. Your body gets time to adjust, and for most people the complaints ease noticeably after a few weeks.
Common side effects
These are described in the product information as very common or common:
- Nausea, especially in the days after a dose increase
- Diarrhoea or constipation
- Vomiting
- Fullness, bloating, burping, heartburn
- Reduced appetite, tiredness, headache, often linked to drinking too little
- With injections: redness or itching at the injection site
What helps day to day
- Smaller portions, eat slowly and stop as soon as you're full
- Avoid very fatty, fried and very sweet foods, especially at the start
- Drink across the day, particularly with diarrhoea or vomiting
- For constipation: increase fibre gradually, drink enough, keep moving
- For heartburn: don't eat right before lying down
- Note your symptoms; it helps decide whether the next increase should wait
When you need help straight away
Rare but important. Don't wait with these signs:
- Severe, persistent abdominal pain that may spread to the back, possibly with vomiting (a sign of pancreatitis)
- Pain in the upper right abdomen, fever or yellowing of the skin (a sign of gallbladder problems)
- Persistent vomiting or diarrhoea where you can't keep fluids down
- Signs of an allergic reaction such as facial swelling or difficulty breathing
- Sudden worsening of vision
Frequently asked questions
Note
This Journal article offers general information. It is not a diagnosis, a prescription or a promise of any result. Whether treatment is suitable for you is decided by a doctor after reviewing your questionnaire. For acute or severe symptoms, contact your GP, the out-of-hours medical service (116117) or, in an emergency, 112. Whether and how a switch or a dose change happens is decided by the doctor in each individual case.
Sources and medical review
Based on European Medicines Agency product information for semaglutide, tirzepatide and liraglutide. Educational only; does not replace an individual medical decision. Medical review pending.
- European Medicines Agency product information for semaglutide, tirzepatide and liraglutide