Why Your Resting Heart Rate Goes Up on Wegovy, Zepbound, and Other GLP-1 Drugs

People who start Wegovy, Ozempic, Zepbound, or Mounjaro watch the scale. Smartwatch wearers may spot a second change: a higher resting heart rate. Heart rate is counted in beats per minute (bpm), and MedlinePlus, the National Library of Medicine's health site, lists 60 to 100 bpm as the normal resting range for adults.

The rise is real and expected. Every U.S. label for these drugs reports it, usually as an average gain of a few beats per minute over placebo. Averages hide a wide spread, though. In the Wegovy weight-loss trials, 26% of adults on the drug had a jump of 20 bpm or more at some clinic visit, compared with 16% on placebo.

Other side effects people notice, such as changes in body temperature and menstrual cycles and hair and nail changes, have their own explainers.

Each label states the heart rate change seen in its own clinical trials:

Teenagers showed the same pattern. In a Wegovy trial in patients aged 12 and older who started with a normal heart rate, 54% on the drug and 39% on placebo had a rise of 20 bpm or more at some point.

Wegovy and Saxenda list the rise as a formal warning: check heart rate regularly, and stop the drug if resting heart rate stays up. The other four labels report it among adverse reactions, and the Mounjaro label says "the clinical relevance of heart rate increases is uncertain." Foundayo, Lilly's daily pill, is a small molecule rather than a peptide. The trials behind these labels differed, so the numbers are not a head-to-head ranking.

Clinic readings capture one moment. Watches record around the clock, including during sleep, and round-the-clock data can show a larger gap. The Saxenda label describes a clinical pharmacology trial that tracked heart rate for 24 hours: on liraglutide, heart rate ran 4 to 9 bpm higher than on placebo, compared with the 2 to 3 bpm average seen at routine visits.

A small Danish trial found a similar pattern. Researchers gave 12 weeks of liraglutide and 12 weeks of placebo, in random order, to people with newly diagnosed type 2 diabetes and stable coronary artery disease, and recorded their heart rhythm for 24 hours at a time. Among 27 participants, liraglutide raised average heart rate by 8.1 bpm and nighttime heart rate by 6.3 bpm. It also lowered heart rate variability, the small beat-to-beat changes that many watches report as "HRV," and reduced measures of parasympathetic activity, the "rest and digest" side of the nervous system. These changes happened even though participants lost weight and their metabolic measures improved.

So a sleeping or 24-hour average may rise more than the label's clinic average, and HRV may fall. A change on a watch is not a diagnosis by itself.

The heartbeat starts in the sinoatrial node, a small patch of tissue in the upper right chamber that works as the heart's natural pacemaker. In a 2018 study of human heart tissue, researchers detected GLP-1 receptor gene transcripts in the sinoatrial node, which made a direct push on the pacemaker an obvious suspect.

Work in mice from the same research group complicated that idea. Liraglutide raised heart rate quickly in living mice, and the beta-blocker propranolol blunted the rise, while atropine, which blocks the vagus nerve's braking signal, did not. When the team tested isolated mouse hearts and atrial tissue with no nerve connections, the drugs did not speed the heartbeat. The authors concluded that GLP-1 drugs raise heart rate through several routes, including the autonomic nervous system, the involuntary network that speeds up and slows down the heart, and that the heart's GLP-1 receptors need nerve input to produce the effect.

The Danish HRV results fit a shift in the balance between the nerves that speed the heart and those that slow it. Not every study agrees. In a small infusion study in healthy young men, the GLP-1 drug exenatide raised heart rate by about 4 bpm without a measurable change in heart rate variability. The leading explanation is still a working model, built mostly on mouse experiments and small human studies, and the details may differ from drug to drug.

A faster resting heart rate draws attention because studies have linked a higher rate and lower heart rate variability with cardiovascular death. For GLP-1 drugs, though, the large outcome trials have been reassuring. These trials count MACE, short for major adverse cardiovascular events, which here means heart attack, stroke, or death from cardiovascular causes.

• LEADER (liraglutide, 9,340 people with type 2 diabetes): 13.0% vs. 14.9% on placebo had a MACE event over a median of 3.8 years, a 13% lower risk.
• SUSTAIN-6 (semaglutide, 3,297 people with type 2 diabetes): 6.6% vs. 8.9% over two years, a 26% lower risk.
• SELECT (semaglutide 2.4 mg, 17,604 adults with heart disease and overweight or obesity but no diabetes): 6.5% vs. 8.0% over about three years, a 20% lower risk.
• SURPASS-CVOT (tirzepatide vs. dulaglutide, a GLP-1 drug with proven heart benefit): 12.2% vs. 13.1%, enough to show tirzepatide was no worse but not that it was better.

These results came despite the heart rate rise. They do not prove the extra beats are harmless, only that the overall effect was favorable or neutral in these groups.

People with heart failure with reduced ejection fraction (HFrEF), in which the heart's main pumping chamber is weakened, are a different case. In the Danish LIVE trial of 241 such patients, liraglutide 1.8 mg daily for 24 weeks raised heart rate by 7 bpm compared with placebo, did not improve pumping function, and was linked to more serious cardiac adverse events. In the U.S. FIGHT trial of 300 patients recently hospitalized with HFrEF, liraglutide did not improve stability after discharge, and a later exploratory analysis found more total adverse events with the drug.

Heart failure with preserved ejection fraction, in which the heart pumps normally but is stiff, looks different so far. The 2026 ADA-EASD type 2 diabetes consensus says semaglutide or tirzepatide should be used to improve symptoms in people with diabetes, obesity, and this form of heart failure (our guide to the consensus).

Retatrutide, survodutide, and mazdutide add activity at the glucagon receptor, and glucagon itself speeds the heart in large doses. In the infusion study in healthy young men, a high-dose glucagon drip raised heart rate by 11 bpm after two hours. In a second part of the study, exenatide and a low dose of glucagon each added about 4 bpm after an hour, and the two together added about 7 bpm.

Trials of the new drugs so far show increases in the same range as GLP-1 drugs:

• Survodutide: in a 16-week Phase 2 trial in type 2 diabetes, average heart rate rose 2.3 to 7.3 bpm across survodutide doses, compared with 5.9 bpm on semaglutide and 1.7 bpm on placebo. One dose group averaged just over 10 bpm at two time points.
• Mazdutide: in a 20-week Phase 2 trial in Chinese adults with type 2 diabetes, heart rate rose 6.4 to 6.6 bpm by the end of treatment, compared with 7.5 bpm on dulaglutide and 1.7 bpm on placebo. In a 24-week Phase 2 obesity trial, increases were 5.4 to 8.8 bpm, compared with 4.8 bpm on placebo.
• Retatrutide: in the 48-week Phase 2 obesity trial published in 2023, heart rate rose with dose, peaked at 24 weeks, and declined after that, according to the paper's abstract.

A 2026 review in the Journal of the American Heart Association concluded that dual glucagon and GLP-1 drugs such as mazdutide and survodutide have "generally" raised heart rate about as much as GLP-1-only drugs. It also noted that at least one other dual agonist was dropped partly because of large heart rate increases, and that each compound behaves differently. Retatrutide has drawn more attention for a different side effect, skin tingling.

The deciding data are still ahead. Boehringer Ingelheim's 5,500-person SYNCHRONIZE-CVOT safety trial of survodutide is listed as completed on ClinicalTrials.gov, but its results were not public when we checked in October 2026. Lilly's 10,000-person TRIUMPH-Outcomes trial of retatrutide is not expected to finish main data collection until 2029.

For most people, the average rise is a few beats per minute. The labels and MedlinePlus point to a few signals worth acting on:

• A racing or pounding heartbeat at rest. The Wegovy and Saxenda patient information tells people to contact their provider if they feel their heart racing or pounding in their chest and it lasts for several minutes.
• A resting pulse above 100 bpm. MedlinePlus advises contacting a provider if your pulse is over 100 bpm without exercise, anxiety, or fever.
• New or different palpitations, especially if you have heart disease or risk factors such as diabetes or high blood pressure.
• Dizziness or fainting. The Wegovy label reports low blood pressure in 1.3% of adults on the drug versus 0.4% on placebo, and fainting in 0.8% versus 0.2%.
• Emergency symptoms. MedlinePlus advises calling 911 for palpitations with chest pain, shortness of breath, unusual sweating, dizziness or lightheadedness, or loss of consciousness.

A watch trend from before and after starting the drug says more than one high reading. Don't stop the medicine on your own; the labels leave that call to the prescriber. People with heart failure, especially HFrEF, should ask their cardiologist how a GLP-1 drug fits with their heart treatment.