Saxenda® (liraglutide) and palpitations

How the Saxenda® documents measure the faster pulse

The US label reports heart rate in several ways, which makes the change easier to picture than a single average would. ^[1] The Canadian monograph repeats the same figures, and the EU summary adds how the rise behaved over time. ^[2][3]

Reading those numbers

An average of 2 to 3 beats is small, but averages hide spread: about one adult in three on Saxenda® had a rise of more than 10 beats at two visits in a row, against one in five on placebo. ^[1] The 24-hour study matters because routine clinic readings are taken in the daytime, and a daily injection keeps the medicine in the body around the clock. ^[1] A separate 3-week study of liraglutide in people with type 2 diabetes and high blood pressure found small increases in 24-hour and night-time heart rate. ^[6]

The EU summary reports that across its phase 3 trials the average rise was 2.5 beats per minute, ranging from 1.6 to 3.6, that it peaked after about six weeks, and that it went away when liraglutide was stopped. ^[2] Its tachycardia entries were mostly mild or moderate, isolated, and usually settled while people kept taking Saxenda®. ^[2] The long-term impact of the higher rate has not been established, the same summary adds. ^[2]

Rhythm findings and heart conditions

Beyond rate, the US label notes that 0.3% of adults on Saxenda® developed a cardiac conduction disorder, described as first-degree heart block or a bundle branch block, against none on placebo. ^[1] The Canadian monograph adds that the PR interval on the ECG lengthened by up to 10 milliseconds in healthy volunteers and asks for caution in people who already have conduction problems or fast heart rhythms. ^[3] It also notes that people with a recent heart attack, unstable angina or more severe heart failure were not studied, and asks for caution with other medicines that raise heart rate or lengthen the PR interval, such as some beta blockers, calcium channel blockers and digoxin. ^[3]

Two outside trials help frame this. In LIVE, 241 people with reduced heart pumping function took liraglutide at the 1.8 mg diabetes dose or placebo for 24 weeks; heart rate rose by about 7 beats per minute and serious cardiac events occurred in 10% versus 3%, which the authors called a concern for this group. ^[4] In the small LEAF trial, adding three months of liraglutide before ablation for atrial fibrillation was linked with fewer recurrences at one year than risk-factor management alone. ^[5] Neither trial used Saxenda® itself. For overall heart safety, the US label cites LEADER, where liraglutide 1.8 mg did not raise the risk of major cardiovascular events in people with type 2 diabetes and heart disease. ^[1]

Why your heart might be racing on Saxenda®

• A direct effect: the rise in resting rate is described as an effect of the medicine itself, and the label treats it as a warning in its own right. ^[1][2]
• Low blood sugar: a fast heartbeat is among its listed signs. The risk is higher in adults with type 2 diabetes using insulin or a sulfonylurea, and in teenagers. ^[1]
• Fluid loss: nausea, vomiting and diarrhoea are the most common Saxenda® reactions, and dehydration can speed up the heart. ^[1][9]
• Lower blood pressure: reactions related to low blood pressure were reported in 1.1% of adults on Saxenda® versus 0.5% on placebo. ^[1]
• Allergic reaction: rare anaphylaxis with liraglutide has included palpitations, low blood pressure and breathlessness. ^[1][2]

Palpitations that have nothing to do with Saxenda®

MedlinePlus lists anxiety and stress, caffeine, nicotine, alcohol, exercise, fever, stimulant drugs, decongestants such as pseudoephedrine and diet pills as everyday triggers. ^[7] Some palpitations come from an abnormal rhythm linked to heart disease, valve problems, abnormal potassium, an overactive thyroid, low oxygen or medicines for asthma, blood pressure or the heart. ^[7] Cleveland Clinic adds pregnancy, anaemia, dehydration and menopause, and notes that palpitations are common and usually harmless. ^[8]

If palpitations began after a new cold remedy, a stronger coffee habit or a stressful week, those deserve a look before the injection gets the blame. Saxenda® users are asked to list every medicine, including over-the-counter products, for their provider. ^[1]

What helps, and what your prescriber may check

MedlinePlus suggests cutting back on caffeine, nicotine and other stimulants, learning ways to reduce stress, trying breathing or relaxation exercises, staying active and not smoking. ^[7] Once a serious cause has been ruled out, it advises not focusing too closely on each flutter, but contacting your provider if the pattern changes. ^[7]

For Saxenda®, the label expects heart rate to be checked at regular intervals as part of usual care. ^[1] A clinician may ask how the beats feel, when they happen and whether they start suddenly, and may order an ECG or a 24-hour heart monitor. ^[7] Writing down the time of day and what you were doing makes that conversation easier. Whether Saxenda® continues is your prescriber’s decision; the label’s rule is that a sustained rise in resting rate means stopping. ^[1]

Saxenda® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.