Side Effects: See also the Warning section. Nausea, vomiting, stomach upset, diarrhea, tiredness, dizziness, or constipation may occur. Nausea usually lessens as you continue to use semaglutide. If any of these effects last or get worse, tell your doctor or pharmacist promptly. Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Vomiting/diarrhea that doesnt stop may result in dehydration. Contact your doctor promptly if you notice any symptoms of dehydration, such as an unusual dry mouth, thirst, or dizziness/lightheadedness. Tell your doctor right away if you have any serious side effects, including: signs of kidney problems (such as change in the amount of urine), vision changes (such as decreased/blurred vision), fast heartbeat, mental/mood changes (such as depression or thoughts of suicide), and signs of low blood sugar (sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness, tingling hands/feet). Get medical help right away if you have any very serious side effects, including signs of pancreas or gallbladder disease (such as nausea/vomiting that doesnt stop severe stomach/abdominal pain). A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including rash, itching/swelling (especially of the face, tongue, or throat), severe dizziness, and trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US, call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.