Heart rate increase in GLP-1 labels

Average changes, label by label

Section 6.1 of each US label gives the mean change in heart rate seen in the trials. Wegovy® and Saxenda® also list it in section 5, the warnings that call for active monitoring ^[1][2]. The table keeps each label’s own reference point; trials differ in people and doses, so the figures are not a ranking.

Larger rises and fast-rhythm reports

• Wegovy®: at some visit, 41% of adults on the medicine had a rise of 10 to 19 beats per minute (34% on placebo) and 26% a rise of 20 or more (16%). In adolescents aged 12 and over with a normal starting rate, rises of 20 or more were seen in 54% against 39%. The label says a trial of Wegovy® tablets found much the same ^[1].
• Saxenda®: rises of more than 10 beats at two visits in a row in 34% against 19%, and of more than 20 in 5% against 2%. At least one resting reading above 100 was recorded in 6% against 4%. Continuous 24-hour monitoring in one study found rates 4 to 9 beats higher than placebo ^[2].
• Mounjaro®: episodes of sinus tachycardia, a fast but regular rhythm, with a rise of 15 beats or more, were reported in 4.6%, 5.9% and 10% at the three doses against 4.3% on placebo, and more often among people enrolled in Japan. The label calls the clinical relevance of the rises uncertain ^[5].
• Foundayo™: tachycardia, counting reports of fast heart rate and sinus tachycardia together, in 3% against 0.9% on placebo ^[7].
• A separate question: the Wegovy® and Saxenda® labels report that semaglutide up to 1.5 mg and liraglutide up to 1.8 mg did not prolong the QTc interval, a measure of the heart’s electrical recovery between beats. That says nothing either way about pulse rate ^[1][2].

What European and Canadian information adds

European package leaflets sort side effects into frequency classes: “common” means up to 1 in 10 people, “uncommon” up to 1 in 100. In the EU, tirzepatide is sold only as Mounjaro®, for diabetes and weight management alike, so there is no separate European Zepbound® document; the Canadian Zepbound® monograph fills that gap ^[10][12].

What studies outside the labels show

A 2017 review gathered published 24-hour heart rate recordings from 1,112 people on GLP-1 medicines. Short-acting ones raised the average rate by about 1 to 3 beats per minute for a few hours at a time. Long-acting ones raised it more and for longer, by day and at night: 6 to 10 beats with liraglutide and albiglutide, 3 to 4 with dulaglutide and long-acting exenatide ^[13]. Semaglutide, tirzepatide and orforglipron were not included.

It is a narrative review rather than a new trial, and most of its authors worked for a company that makes a short-acting GLP-1 medicine, which is worth knowing when it compares the two groups. On outcomes, it concluded that cardiovascular trials up to then had not linked the rise to extra cardiovascular risk in type 2 diabetes, while noting that a marked rise may matter in advanced heart failure ^[13]. What the later SELECT and SURPASS-CVOT trials found about heart attacks and strokes is covered in the Wegovy® and Mounjaro® heart indication articles.

Why the pulse goes up

• What the labels support: they describe the rise and how often it happens, but none of them names a cause. The European Saxenda® information adds that the rise reversed after liraglutide was stopped, so it depends on ongoing treatment ^[11].
• Proposed but not measured: the 2017 review suggests that the medicines may act directly on the sinus node, which sets the heart’s rhythm, and/or through stimulation of the sympathetic nervous system, possibly related to how long each medicine acts. Its authors say the mechanism remains to be worked out ^[13].
• General background: MedlinePlus notes that a fast pulse can also be a sign of dehydration or infection ^[15]. Dehydration is a known risk on days of vomiting or diarrhea, which the labels warn about separately ^[1].

Other reasons the heart may race

Palpitations, the feeling that the heart is pounding or racing, are usually not serious, according to MedlinePlus. Common triggers include anxiety and stress, caffeine, nicotine, alcohol, fever, exercise, diet pills and decongestants such as phenylephrine or pseudoephedrine. Less often they reflect an abnormal rhythm, linked for example to heart disease, a valve problem, low potassium, an overactive thyroid or some asthma, blood pressure and heart medicines ^[14].

Two label sections list a fast heartbeat among other warning signs. It can be one sign of low blood sugar, a risk mainly for people who also use insulin or a sulfonylurea, and a very rapid heartbeat can be part of a serious allergic reaction ^[1]. The Canadian Zepbound® monograph also asks people to mention medicines that may raise heart rate ^[12].

What may help

MedlinePlus lists simple steps for palpitations once a serious cause has been ruled out: cutting back on caffeine, nicotine and other stimulants, learning ways to manage stress, trying relaxation or breathing exercises, regular exercise and not smoking. It also suggests not watching the heartbeat too closely, since that can add stress, but contacting a provider if the palpitations suddenly increase or change ^[14].

If your prescriber asks for pulse readings, MedlinePlus describes measuring a resting heart rate after sitting quietly for a while and counting for a full minute ^[15]. Write the reading down with the time rather than judging it yourself. The labels leave any decision about stopping or continuing the GLP-1 medicine to the prescriber ^[1][2].

Wegovy®, Ozempic®, Rybelsus® and Saxenda® are registered trademarks of Novo Nordisk A/S. Mounjaro® and Zepbound® are registered trademarks and Foundayo™ is a trademark of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Novo Nordisk or Eli Lilly and Company.