Side effects and reasons to pause
Know what needs attention
Keep this in mind
Bring concerns into the consultation before agreeing to treatment. Ask which symptoms need a message, a prompt review or emergency help.
Medicine safety information checked September 26, 2026.
Stomach problems are common
Wegovy injection’s official medicine information, called the label, lists common side effects: constipation, feeling sick to your stomach, vomiting and diarrhea. Wegovy side-effect information
In its adult weight-loss studies, 44% of people on Wegovy injection felt sick to their stomach, compared with 16% on a dummy injection.
The label also reports severe stomach reactions. Losing fluid through vomiting or diarrhea has been linked to kidney injury. Warnings about fluid loss
Severe gastroparesis means very slow stomach emptying; the label does not recommend Wegovy for people with that condition.
Keep this in mind
The small gland called the thyroid sits in your neck. The warning about tumors there needs both parts: what happened in animals, and what remains unknown in people.
Understand the thyroid caution
The Food and Drug Administration (FDA) has no stronger warning format than a boxed warning. Semaglutide’s warning describes thyroid tumors in rats and mice; whether it causes those tumors in humans is unknown. The boxed warning
The rare cancer named in this warning involves a particular group of thyroid cells called C cells. Its medical name is medullary thyroid cancer. A personal or family history of that specific cancer means the label says semaglutide must not be used.
If all you know is that a relative had thyroid cancer, tell the person treating you. Ask for help finding the exact diagnosis before deciding on treatment.
The label also rules semaglutide out for people with MEN 2, short for multiple endocrine neoplasia type 2. The name refers to a rare condition involving tumors in glands that make hormones, the body’s chemical messengers. It is inherited, meaning it can pass from parent to child. If that name appears in your family’s medical history, bring it to the visit. If you are unsure of a family diagnosis, ask for help checking it.
A previous serious allergic reaction to semaglutide or any of its other ingredients also rules it out.
Keep this in mind
A safety claim in an advert still needs checking. Look at the proposed medicine and the way care is provided.
Pause at these claims and gaps
The FDA warns against two service gaps: selling medicine without checking the need for a prescription, and having no licensed doctor available for questions once it arrives. Another FDA warning concerns offers that describe a compounded drug as equivalent to an FDA-approved medicine. Compounded medicine is made to order, with a doctor or pharmacy preparing it. FDA warning signs for online care
Watch for “not for human consumption” on a product offered for people to use; another warning label is “for research purposes”. These words do not mean an approved medicine that has been studied. The FDA advises against buying these products because their quality is unknown and they could be harmful. FDA warning about research-use labels
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