Why a GLP-1 Raises Your Heart Rate, and When Palpitations Matter

Every GLP‑1 drug raises resting heart rate, usually by a few beats a minute, and some people notice it as a pounding or racing heart. Whether your own leaflet warns you about it depends less on how big the effect is than on which brand you take. And some palpitations on these drugs come from something else, such as low blood sugar, too much thyroid medication or caffeine.

How much it rises, and which labels warn about it

Ozempic and Wegovy contain the same molecule, yet only Wegovy carries the warning. The gap is widest on tirzepatide. Mounjaro’s label has no heart-rate warning, but its own trial data show episodes of a fast sinus rhythm with a rise of at least 15 beats a minute in 10% of people on 15 mg against 4.3% on placebo, climbing with each dose, and in 23% against 7% in the small group of patients enrolled in Japan. The label says the clinical relevance is uncertain.^[4] Foundayo reports the largest average rise of any label, and tachycardia in 3% against 0.9%.^[7] So someone on Zepbound or Ozempic who looks up palpitations will not find in their own leaflet the instruction a Wegovy user gets.

The average hides the spread

A rise of a few beats a minute on average means some people rise much more. On Wegovy, 26% of adults had a jump of 20 beats a minute or more at some visit, against 16% on placebo, and 41% against 34% had a jump of 10 to 19. In teenagers with a normal starting heart rate, 54% against 39% had a jump of 20 or more.^[1] Saxenda counts differently, requiring the rise at two visits in a row: more than 10 beats a minute in 34% against 19%, and more than 20 in 5% against 2%.^[2] Because the two labels count differently, their percentages cannot be compared. Saxenda also reports that with 24-hour monitoring the rise was 4 to 9 beats a minute over placebo, larger than the clinic readings suggested.^[2]

Dose, timing, and what happens when you stop

On tirzepatide the rise follows the dose: in SURMOUNT-1 it was 0.5, 2.2 and 2.5 beats a minute above placebo at 5, 10 and 15 mg.^[3] Semaglutide is less tidy, and tripling the injected dose to 7.2 mg did not produce a correspondingly bigger rise.^[1] In pooled data on older GLP-1 drugs, the rise was already visible within two weeks of starting.^[13]

It lasts as long as the drug does. In SELECT, heart rate on semaglutide 2.4 mg was still 3.1 beats a minute above placebo at two years,^[1] and in LEADER, liraglutide ran 3.0 beats higher at three years.^[14] The rise also reverses. In the two trials where people who had been on the drug were randomly switched to placebo, heart rate fell about 5 beats a minute on placebo against about 2 on continued treatment, for semaglutide and tirzepatide alike.^[1][3] In the pooled older-drug data, it was back to where it started 10 weeks after stopping.^[13] Drugs that add glucagon to GLP-1 are watched for the same effect; see what survodutide’s trials show on heart rate.

Why it happens

GLP-1 receptors have been found on cells of the sinus node, the small cluster of cells that sets the pace of each heartbeat, in human and monkey tissue.^[9] Whether the drugs act there directly or through the nervous system is still argued. The same research group ran two small human studies and reached opposite conclusions: in healthy men, the rise came with signs of increased nervous-system drive; in people with type 2 diabetes, it came without them, pointing to the pacemaker itself.^[10][11] A review of 24-hour monitoring studies concluded the mechanism remains to be worked out.^[12]

Beta blockers, which slow the heart, do not prevent the rise. In the pooled older-drug data, heart rate rose in people already taking a beta blocker as well as in those who were not; if anything the rise was larger in beta-blocker users, although those groups differed in other ways.^[13] Most people in the big outcome trials were on a beta blocker already, 70% in SELECT.^[1]

Does it cancel out the heart benefit?

The trials that recorded the rise are the same trials that found fewer heart attacks, strokes and cardiovascular deaths. In SELECT, in people with heart disease and excess weight but no diabetes, semaglutide 2.4 mg cut those events by about a fifth: 6.5% against 8.0%, hazard ratio 0.80.^[16] LEADER found a hazard ratio of 0.87 for liraglutide while heart rate ran 3 beats higher,^[14] and SUSTAIN-6 found 0.74 for semaglutide.^[15] Tirzepatide’s outcome trial, SURPASS-CVOT, compared it with another GLP-1 drug rather than placebo; it proved at least as good, with a hazard ratio of 0.92, but not better.^[17] When researchers tested whether the change in heart rate helped explain the drug’s effect on deaths in the exenatide trial EXSCEL, it did not.^[18] We found no study showing that the rise itself worsens outcomes in these populations, although the lack of such a study does not prove the rise is harmless.

The exception is heart failure with a weakened pumping chamber, known as reduced ejection fraction. In the LIVE trial in that group, liraglutide raised heart rate by 7 beats a minute, and serious cardiac events occurred in 10% against 3% on placebo; the authors called the result a concern.^[19] No current label mentions ejection fraction. Anyone with that diagnosis should have a cardiologist involved in the decision.

On rhythm, the newer evidence is broadly reassuring for the class. A 2026 pooling of 24 obesity trials found GLP-1 drugs lowered new atrial fibrillation by 18%, with no difference between agents.^[20] Most trials, though, only picked up atrial fibrillation through routine side-effect reports, and none had enough patients to test it properly.^[22] A September 2026 analysis limited to tirzepatide found no significant change in atrial fibrillation but a higher rate of arrhythmias of any kind, based on few events.^[21] GLP-1 drugs and atrial fibrillation covers the rhythm question in more depth.

Palpitations that point somewhere else

• Low blood sugar. Every Medication Guide lists a fast heartbeat among its signs, and ties the risk to insulin or a sulfonylurea taken alongside.^[3] GLP-1 drugs and low blood sugar sets out who is at risk.
• Too much thyroid hormone. Levothyroxine in excess causes palpitations and a fast pulse,^[8] and the dose that was right at a higher weight can become too much as weight falls; one published case on semaglutide presented mainly as palpitations.^[23] Oral semaglutide also raises levothyroxine levels in the blood by about a third.^[6] Both effects are explained in what a GLP-1 does to levothyroxine. The thyroid test nobody reordered covers the monitoring gap.
• Coffee and energy drinks. In a randomized trial with continuous heart monitoring, coffee days brought about 50% more skipped beats from the lower chambers, but not more early beats from the upper chambers.^[24] That is not specific to GLP-1 drugs, but it is a common and fixable cause. Stimulant weight-loss drugs belong on the same list: phentermine’s label names palpitations, and phentermine and a GLP-1 together covers what is known about taking both, while phentermine vs a GLP-1 compares the two as alternatives. ADHD stimulants raise heart rate too; see Adderall and a GLP-1.
• Low blood pressure and fluid loss, or anxiety. Plausible, and often suggested, but neither has been studied as a cause of palpitations on these drugs (what is known about anxiety itself is in GLP-1s and anxiety). Dizziness and blood-pressure pills on a GLP-1 covers what is known about blood pressure falling.