Wegovy side effects

The common ones

In the STEP trials, nausea was reported by around 4 in 10 people at some point, mostly mild and short-lived. The mechanism is the medicine itself: a slower stomach means big or fatty meals linger.

• Nausea, worst in the 48 hours after a dose increase. Cold, plain food and small portions help.
• Constipation, fibre, fluids and walking first. Macrogol from a pharmacist if needed.
• Diarrhoea, usually settles in days. Hydration is the priority.
• Reflux and bloating, eat earlier, stay upright after meals, cut fat for a few days after each dose.
• Fatigue, often undereating. Check protein and total calories before assuming it is the medicine.
• Dizziness, can reflect dehydration or, if you take diabetes medicines, low blood sugar. Tell us which.

What eases them

• Half portions, eaten slowly, stopping at the first fullness signal.
• Two litres of fluid across the day in small sips.
• Bland, cold or room-temperature food on rough days, hot smells amplify nausea.
• Holding a dose for an extra 4 weeks instead of stepping up. Normal, safe, common.
• Ginger tea or ginger capsules, modest but useful evidence for nausea.

The rare but serious ones

Contact 111 or your GP promptly for right-upper-abdominal pain with fever or jaundice (gallbladder), persistent vomiting (dehydration and kidney risk), or, if you have diabetic retinopathy, any sudden vision change. Rapid blood sugar improvement can temporarily worsen retinopathy, so eye screening matters during treatment.

What the long-term data shows

Semaglutide has the deepest safety dataset in this class: years of use in diabetes (as Ozempic) plus the obesity trial programme. The SELECT trial followed over 17,000 people for about 3 years and found no new safety signals, and a 20% reduction in major cardiovascular events. Long-term does not mean risk-free, but it does mean well-mapped.

Report suspected reactions

Tell the clinical team first, then report through the MHRA Yellow Card scheme. Patient reports are how rare problems surface early.