Weight-loss injections: effects, risks and stopping

This mainly means the active substances semaglutide, tirzepatide and liraglutide. Semaglutide acts like the body's own hormone GLP-1 and regulates appetite: you feel full sooner and less hungry.^[2] Tirzepatide also acts like the hormone GIP.^[3]

Semaglutide is now also available as a tablet for adults.^[2] For the substance orforglipron, the EMA recommended approval in October 2026. A decision by the European Commission was still pending as of 6 November 2026.^[4]

They are approved as an addition to a reduced-calorie diet and more physical activity, for adults with a BMI from 30, or from 27 with at least one weight-related condition such as high blood pressure or sleep apnoea.^[5][6] What BMI says is under BMI and waist size.

For adolescents from 12, separate conditions apply for semaglutide and liraglutide. For weight management, tirzepatide is approved for adults only.^[5][6][23]

These medicines are neither approved nor intended for cosmetic weight loss, say the EMA and the European medicines agencies.^[1] People outside the approved use should get lifestyle advice instead.^[1]

The stomach and gut are affected most often. With semaglutide, 43.9% had nausea over 68 weeks against 16.1% on placebo, and 24.5% vomiting against 6.3%. This mainly occurred while the dose was being raised. 4.3% stopped because of it.^[5]

The picture with tirzepatide is similar, and the full lists are in the product information.^[6]

• Pancreas: Severe, lasting abdominal pain that may spread to the back needs medical attention at once.^[5]
• Gallbladder: Gallstones and inflammation occur, more likely with greater weight loss.^[5][6]
• Kidneys: Vomiting and diarrhoea can dehydrate you and strain the kidneys. So drink enough.^[5]
• Eyes: For semaglutide, a certain optic nerve condition counts as a very rare side effect, in up to 1 in 10,000. With sudden loss of vision, see a doctor at once.^[7] With diabetes, retinal disease can also worsen in the short term.^[5]
• Anaesthesia: Tell your team before surgery that you take such a medicine. Cases of inhaled stomach contents have been described.^[5]
• Mood: The EMA found no causal link with suicidal thoughts for semaglutide and liraglutide.^[8] Tirzepatide was not part of this review. If your mental health gets worse, talk to your doctor at once.

Thyroid tumours occurred in rodents. Their relevance for humans is considered low but not fully excluded.^[5] More on muscle under Strength training and muscle during weight loss.

• Pregnancy: Semaglutide must not be used during pregnancy and must be stopped at least 2 months before a planned pregnancy. Tirzepatide is not recommended during pregnancy and should be stopped at least 1 month before. Contraception is advised for women who can become pregnant.^[5][6]
• Breastfeeding: The rules differ by substance, so talk to your doctor.^[5][6]
• Other conditions: Semaglutide is not studied or recommended in type 1 diabetes and severe kidney impairment, among others. Caution applies after pancreatitis and with inflammatory bowel disease.^[5]
• Other medicines: With insulin or sulfonylureas, the risk of low blood sugar rises.^[5]
• Eating behaviour: Experts advise looking at eating behaviour and mental health beforehand.^[9] If you have an eating disorder or are afraid of one, read Stress and emotional eating.

According to the S3 guideline, weight usually rises again once the medicines end.^[10] The EMA describes obesity as a chronic disease and these medicines as intended for long-term use.^[1]

One year after semaglutide ended, 327 participants of a study had regained on average two thirds of their loss, and metabolic values moved back towards the start. Lifestyle support ended there along with the medicine.^[11] After switching to placebo, weight rose by 14.0% within a year in a study of 670 people on tirzepatide.^[12]

A review of 37 studies found an average regain of 0.8 kg per month for semaglutide and tirzepatide. Longer values there are projections, and the data only reach 12 months.^[13] These are averages. No study predicts how it will go for you. So plan stopping together with your doctor. More under Keeping weight off.

The S3 guideline says medicines should only be used together with a programme of nutrition, movement and behaviour, and reviewed regularly.^[10] The German Diabetes Society advises combining movement with enough protein to preserve muscle.^[14] With reduced kidney function, this does not apply without medical advice.^[14]

The studies behind the guideline mostly ran for 1 to 2 years.^[10] The WHO, too, gives only conditional recommendations and names missing long-term data as a reason.^[15]

As of November 2026, people with statutory health insurance in Germany pay for weight-reduction medicines themselves. Section 34 of Book V of the Social Code excludes medicines for regulating body weight.^[16] The Federal Joint Committee saw no leeway here, even at a BMI over 30.^[17] For type 2 diabetes, insurers can pay for products approved for it.^[17]

This is under political debate, but nothing has been decided.^[18] Check again before you decide, as this is changing.

The EMA and European agencies warn of a sharp rise in illegal products, often sold through fake websites and social media. They may contain no active substance or harmful substances.^[19] In 2023, falsified pens appeared in Europe which, according to the German agency BfArM, contained insulin instead of semaglutide.^[20]

• Never buy without a prescription or outside pharmacies.^[19]
• Distrust offers on social media and claimed endorsements by authorities.^[19]
• For mail-order pharmacies, look for the EU safety logo and the register.^[21]

Online prescriptions call for caution too: in test purchases by the consumer centre NRW in March 2026, several platforms issued prescriptions without checking identity or weight.^[22] Good support looks different. More under When to get medical advice.