Drug facts

Semaglutide and headaches

By David Chen·Editor·Reviewed September 2026

How common it was¹

Headache is sixth in the label’s table of reactions reported in 2% or more of adults, the first row that is not a stomach or bowel complaint. The arm was 2,116 adults on semaglutide 2.4 mg against 1,261 on placebo, in trials of up to 68 weeks.

The placebo arm shows how common headaches were anyway: one participant in ten reported one with no drug at all. Of the 14 people in every 100 on semaglutide who reported a headache, roughly 10 would be expected without it. Read with its placebo column, this is among the rows in the side-effects table that the drug explains least.

In the other trials¹

The label reports headache in two more tables, and both put the drug and placebo rates close together:

The 7.2 mg table lists only the reactions reported more often at 7.2 mg than at both 2.4 mg and placebo, so headache qualified, by one percentage point. These are different trials from the ones in the first table, with their own placebo rate, so the 8% here and the 14% above are not a contradiction and should not be compared directly.

On Ozempic²

Headache is not in the Ozempic label’s table of common reactions, which lists those reported in 5% or more of patients in its placebo-controlled diabetes trials. The word appears twice in the whole Ozempic document. One is in the postmarketing list, under “Neurologic: dysesthesia, headache.” That list is built from reports sent in voluntarily after approval, and the label says such reports cannot reliably establish how often something happens or whether the drug caused it. The other is in the Medication Guide’s list of low-blood-sugar signs, the same list the Wegovy guide carries.

When a headache is a sign of low blood sugar⁴

The Wegovy Medication Guide lists headache among the signs of low blood sugar, alongside dizziness or light-headedness, sweating, shakiness, blurred vision, weakness, hunger, a fast heartbeat and confusion. It raises low blood sugar as a risk for people with type 2 diabetes, especially those also taking insulin or a sulfonylurea. The Ozempic guide carries the same list.

The prescribing information puts numbers on it³. In the trial of adults with type 2 diabetes, blood sugar below 54 mg/dL was reported by 6.2% on Wegovy against 2.5% on placebo, and the risk was higher with a sulfonylurea. For people without diabetes, the label says low blood sugar was not systematically captured in the weight-reduction trials, so it gives no rate. What the label says about insulin and sulfonylureas →

What the label does not say¹

“Headache” appears six times in the Wegovy label: in the summary list of common reactions, in each of the three adverse-reaction tables, and twice in the Medication Guide (its list of common side effects and its list of low-blood-sugar signs). None of the six says when headaches start, how long they last, or why they happen. Any page that explains the cause is not reading it from this label.

What none of this covers

Nothing here is medical advice, and this page suggests no remedy. Whether a side effect needs attention, and what kind, is a question for the prescriber. The full list of reported reactions is on side effects, and fatigue has its own page. See the medical disclaimer.