Dizzy or light-headed

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What the labels report

Dizziness was reported by 8% on Wegovy 2.4 mg against 4% on placebo, and 4 to 5% on Zepbound against 2%.^[1][2] Events related to low blood pressure (hypotension, orthostatic hypotension, meaning a drop on standing) were reported in 1.3% versus 0.4% on Wegovy, and fainting in 0.8% versus 0.2%. The label says some were linked to gut side effects and fluid loss.^[1] In the Zepbound trials, hypotension was 1.6% versus 0.1%.^[2]

Blood pressure medicines

Both labels say low blood pressure was more common in people also taking blood pressure medicines. On Zepbound it was 2.2% in people on those medicines versus 1.2% in people not on them.^[1][2] As weight comes down, blood pressure often falls too, so a dose that was right before may become too much. Changing a blood pressure medicine is a prescriber decision.

Heart rate

Semaglutide raises the resting heart rate by 1 to 4 beats per minute on average. At some visit during the trials, 26% on Wegovy versus 16% on placebo had a rise of 20 beats per minute or more. The label asks prescribers to monitor heart rate.^[1] A racing heart with dizziness can also be a sign of dehydration.

When to call

• Fainting, or nearly fainting
• Dizziness every time you stand, with little urine after vomiting or diarrhea
• A resting heart rate that stays high, or a pounding or irregular heartbeat
• Shakiness, sweating or confusion if you take insulin or a sulfonylurea (possible low blood sugar)

The short version

Questions to bring to your prescriber

Print these or screenshot them. They are conversation starters, not a checklist of things to do.

• Should my blood pressure medicines be reviewed as my weight comes down?
• Should I check my blood pressure at home, and what reading would worry you?
• Is my heart rate something you want to monitor?

Sources

Every number on this page traces to one of these. "Primary read" means the full paper or label was read; "abstract only" means only the abstract was available; "secondary" means the figure was taken from a named review.

1. Novo Nordisk / FDA. Wegovy (semaglutide) injection and tablets, prescribing information, revised 06/2026. label
2. Eli Lilly / FDA. Zepbound (tirzepatide) prescribing information, revised 08/2026. label

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