Wegovy (semaglutide) is a once-weekly injectable medicine that supports weight loss by reducing appetite and helping you feel fuller for longer. Use it exactly as prescribed alongside a healthy diet and increased physical activity. Common side effects include nausea, vomiting, diarrhoea and constipation, particularly when treatment begins. Seek urgent medical advice if you develop severe abdominal pain, persistent vomiting or symptoms suggestive of pancreatitis.