Side effects of weight-loss injections, and who should avoid them.

Common side effects

These are usually worst in the days after starting or after a dose increase, and they ease with time:

• Nausea, the most common side effect. It is reduced by smaller meals, eating slowly and stopping at the first sign of fullness.
• Constipation or diarrhoea. Fluids and fibre help.
• Reflux, burping and bloating, especially after fatty or large meals.
• Tiredness in the first weeks, often linked to eating much less.
• Injection-site redness. Rotating sites helps.

Serious side effects: seek medical care

• Severe, persistent abdominal pain, sometimes spreading to the back, with or without vomiting. This could be pancreatitis.
• Pain in the upper right abdomen, fever or yellowing of the eyes. This could be gallbladder disease, which is more likely with rapid weight loss.
• Repeated vomiting or being unable to keep fluids down. This risks dehydration and kidney injury.
• Shakiness, sweating and confusion if you also take insulin or a sulfonylurea. These are signs of low blood sugar.
• Swelling of the face or throat, or difficulty breathing. This is an allergic reaction and an emergency.
• Changes in vision in people with diabetic eye disease.

Who should not use them

• Anyone pregnant, breastfeeding or trying to conceive. Medicines like semaglutide should be stopped well before a planned pregnancy, on medical advice.
• Anyone with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2 (MEN2)
• Anyone with a previous serious allergic reaction to the medicine

Use with caution and close review: past pancreatitis, gallbladder disease, severe stomach-emptying problems, kidney disease, diabetic eye disease, or a current or past eating disorder.

Less obvious points

• Muscle loss. A meaningful share of the weight lost can be lean tissue. Adequate protein and strength training protect it.
• Hair shedding. This can follow rapid weight loss and usually recovers.
• The contraceptive pill. Tirzepatide can reduce how well oral contraceptives work around the time of starting and after each dose increase. A barrier method or a non-oral contraceptive is advised.
• Surgery and sedation. Slowed stomach emptying matters for anaesthesia. Always tell the surgical team you are on one of these medicines.

Reporting side effects in Kenya

Suspected side effects and poor-quality medicines can be reported to the Pharmacy and Poisons Board, including through the USSD code *271#.