The heart rate warning in numbers
Section 5.9 of the US label is titled Heart Rate Increase. It is based on heart rate measured at routine trial visits rather than on how people felt, so it shows how often the pulse rose, not how often people noticed palpitations. [1]
| Measure | Source and population | Wegovy® | Placebo |
|---|---|---|---|
| Average change in resting heart rate | US, adults, weight trials [1] | +1 to 4 beats/min vs placebo | — |
| Largest rise of 10–19 beats/min at any visit | US, adults [1] | 41% | 34% |
| Largest rise of 20 beats/min or more | US, adults [1] | 26% | 16% |
| Largest rise of 20 beats/min or more | US, adolescents with normal starting rate [1] | 54% | 39% |
| Rise of 10 beats/min or more at any time | EU, STEP 1–4 [2] | 67.0% | 50.1% |
| Increased heart rate as a reported reaction | EU SmPC; Canadian monograph [2][3] | Uncommon; under 1% | — |
What the label asks of you and your prescriber
The label tells prescribers to check heart rate at regular intervals, in line with usual practice, and to stop Wegovy® if a person’s resting heart rate stays raised. It asks patients to report palpitations or a racing heartbeat while at rest. [1] The Medication Guide puts this in plain terms: tell your provider if your heart races or pounds in your chest and the feeling lasts for several minutes. [1]
The same findings were seen with Wegovy® tablets, according to the label. [1] A separate study found semaglutide did not prolong the QTc interval, a measure of the heart’s recovery between beats, at doses up to 1.5 mg. [1]
The Canadian and EU view
The Canadian monograph includes the same heart rate warning and adds two points. It asks for caution in people whose heart conditions, such as fast rhythm disorders, could be made worse by a higher heart rate. It also says semaglutide lengthens the PR interval on an ECG, which reflects how electrical signals pass through the heart, and asks for caution in people with conduction problems such as heart block or a history of rhythm disturbances, and when it is combined with other medicines that lengthen the PR interval, such as certain heart rhythm medicines, calcium channel blockers, beta-blockers and digoxin-type medicines. [3]
The EU and Canadian patient leaflets list “fast heartbeat” as an uncommon side effect, affecting up to 1 in 100 people. [2][3] In teenagers, the Canadian monograph reports rises of 20 beats per minute or more in 36.4% on Wegovy® and 33.3% on placebo, a different analysis from the US figure for teens with a normal starting rate. [3]
Putting the heart rate rise in context
SELECT followed 17,604 adults with established heart disease and overweight or obesity, without diabetes, for an average of almost 40 months. A first major cardiovascular event (cardiovascular death, heart attack or stroke) occurred in 6.5% on semaglutide 2.4 mg and 8.0% on placebo. [4] Wegovy® is now approved to reduce that risk in this group. [1]
That result is about heart attacks and strokes across a large population. It does not tell any individual that palpitations are harmless, and the label’s instruction to report a racing heart at rest still applies. [1] Adverse events led 16.6% on semaglutide and 8.2% on placebo to stop treatment in SELECT. [4]
Other reasons the heart can race on Wegovy®
- Low blood sugar: a fast heartbeat is one of its signs in the Medication Guide, mainly for people with type 2 diabetes who also use insulin or a sulfonylurea. [1]
- Fluid loss: vomiting or diarrhea can dehydrate you, [1] and a rapid heartbeat is a sign of more severe dehydration. [6] The label also reports low blood pressure reactions in 1.3% vs 0.4% and fainting in 0.8% vs 0.2%. [1]
- Allergy: a very rapid heartbeat with swelling, severe rash or breathing trouble can be a serious allergic reaction. [1]
- Everyday triggers: MedlinePlus lists anxiety, caffeine, nicotine, alcohol, fever, exercise, decongestants and diet pills, and, for true rhythm problems, heart disease, low potassium, an overactive thyroid and some asthma, blood pressure or heart medicines. [5]
Steps that general guidance describes
To limit palpitations, MedlinePlus suggests cutting back on caffeine, nicotine and other stimulants, learning ways to reduce stress and anxiety, relaxation or breathing exercises, yoga or similar practices, regular exercise and not smoking. Once a serious cause has been ruled out, it advises not focusing too closely on each flutter, but to contact a provider if they suddenly increase or change. [5]
Over-the-counter cold and decongestant products can make palpitations worse, [5] so ask a pharmacist before using them. If you have a heart condition or take heart rhythm medicines, make sure your prescriber knows before and during Wegovy® treatment. [3]
Wegovy® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Palpitations with chest pain, shortness of breath, unusual sweating, dizziness or loss of consciousness | Emergency services (911 or local number) | Emergency | MedlinePlus [5] |
| Very rapid heartbeat with swelling of the face or throat, severe rash or trouble breathing | Stop Wegovy® and get emergency help | Emergency | Medication Guide [1] |
| Heart racing or pounding at rest for several minutes | Your prescriber | Today | Medication Guide [1] |
| Resting pulse over 100 without exercise, anxiety or fever, or new or different palpitations | Your provider, right away | Today | MedlinePlus [5] |
| Occasional flutters that you have not mentioned before | Raise at your next visit | At your next appointment | Label §5.9 [1]; MedlinePlus [5] |
