Do GLP-1 Medicines Raise Heart Rate? (October 2026)

01 · The core answer

Do GLP-1 medicines raise resting heart rate?

Some people do notice a higher resting pulse while taking a GLP-1 medicine, and it is a reasonable thing to monitor. The UK patient leaflet lists a fast pulse as a common side effect of Mounjaro, affecting up to 1 in 10 people.¹³

The practical position is simple. A small, steady change that you can measure and that does not bother you is something to mention at your next review. A large, sudden or symptomatic change is something to raise with your prescriber promptly; a racing heart, chest pain or fainting needs medical help straight away. Our guide on Mounjaro and heart rate goes into the tirzepatide-specific picture in more depth.

02 · Both directions

Does a GLP-1 medicine lower heart rate instead?

People ask about both directions, and the honest answer is that pulse can move either way for reasons unrelated to the medicine. Losing weight, becoming fitter and eating differently can all shift resting pulse over time. Illness, dehydration and stress can push it the other way.

If your pulse seems unusually slow, with dizziness or faintness, read our page on whether Mounjaro can cause a low heart rate. If it seems fast or fluttery, our pages on a high heart rate and a rapid heart rate cover what to watch for and when to get checked.

03 · What to do next

Is this relevant to you, and what next?

This matters most if you already track your pulse on a watch or app, if you have a known heart rhythm condition, or if you are considering treatment and want to know what to watch for. Treatment is prescribed after a consultation reviewed by a GPhC-registered prescriber, who can take your heart history into account.

If you are weighing up treatment, you can read about the Mounjaro pen and how the consultation works. Our wider weight loss clinic pages explain what ongoing support looks like, including monthly reviews and side-effect support from our prescribing team.

04 · How the medicine works

How GLP-1 and GIP medicines work

Mounjaro contains tirzepatide, which acts on two gut-hormone receptors at once. Tirzepatide is the first treatment of its kind to activate two natural gut-hormone receptors at once: GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin.¹

In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.¹ Eating and drinking less than usual is one of the everyday things that can influence how your heart behaves.

05 · Reading your pulse

Resting heart rate, variability and palpitations

Resting heart rate is how fast your heart beats when you are calm, still and have not just eaten, exercised or had caffeine. It is the number that wearables and blood pressure monitors report.

Heart rate variability is different. It describes how much the time between beats naturally varies, and watches estimate it from your pulse. It is sensitive to sleep, alcohol, stress, illness and training, and different devices calculate it in different ways. For that reason a variability score is hard to compare between brands or even between nights, and we would not treat a dip on a single morning as meaningful.

Palpitations are a sensation rather than a measurement. You may feel your heart pounding, fluttering or skipping while a monitor shows a normal rate. A pattern of them is worth telling your prescriber about; a racing heart, or palpitations with chest pain or fainting, need medical help straight away.

Keeping these three ideas apart helps. A resting rate is a number, variability is a trend estimated by a device, and palpitations are a symptom. When you speak to a prescriber, describe which of these you are noticing, how often, and what you were doing at the time.

06 · Everyday pulse factors

Everyday factors that move your pulse during weight loss

Several ordinary things change pulse for anyone, and many of them shift when you start a weight-management programme. Sorting these out first often explains a change without needing to blame the medicine.

Hydration. If you feel less hungry, you may also drink less without noticing. Being short of fluid is a familiar reason for a faster resting pulse, and sipping water through the day is an easy thing to try.

Eating much less. A smaller appetite is the intended effect of treatment, but skipped meals and very low intake can leave you feeling light-headed or jittery. Regular, balanced meals, even small ones, are a sensible baseline.

Caffeine and alcohol. If you swap meals for coffee, or find alcohol hits differently now, your pulse may show it. Cutting back for a few days is a simple test.

Sleep and stress. Short or broken sleep, work pressure and anxiety about starting treatment all affect resting pulse, as does a recent illness or fever.

Fitness and activity. Treatment works alongside a reduced-calorie diet and increased physical activity.¹ Where you measure also matters: a reading taken just after climbing stairs is not a resting reading.

None of this means a persistent change should be ignored. It means you should check the simple causes first, then bring a clear pattern to your prescriber if it continues.

07 · Tracking it properly

How to track your pulse so the numbers mean something

A useful reading is a repeatable one. Measure at the same time of day, ideally after sitting quietly for a few minutes, before coffee and before exercise. Use the same device each time, because watches, chest straps and cuffs do not always agree.

Look at the pattern over days and weeks, not at a single reading. One high number after a bad night or a stressful meeting says very little. A steady drift that persists across calm mornings says more.

It also helps to record what else is going on: the day you inject, how much you have eaten and drunk, your sleep and any symptoms such as dizziness or a pounding sensation. That context lets a prescriber separate a medicine effect from a lifestyle one. If you want somewhere to keep it all, our free companion app, GLPTrackr, is designed for tracking a GLP-1 journey on iOS and Android.

Bring the log to your monthly review. Our prescribing team carries out ongoing reviews, dose-titration and follow-up assessments, and side-effect support is part of that aftercare, so a clear record makes the conversation quicker and more useful.

If you want a concise summary for your own notes, write down your typical calm reading before treatment, your reading now, and the dates it changed. Even a rough baseline from before your first dose is valuable, because without it nobody can say whether anything has moved at all.

08 · When to get help

When a heart rate change needs medical attention

Some symptoms should never wait for a routine review. Chest pain, fainting, difficulty breathing, or a racing heart that does not settle with rest need medical help straight away. Call the emergency services or go to A&E rather than messaging a pharmacy.

For less urgent but persistent changes, such as a pulse that stays higher than usual across calm mornings, tell your prescriber. Tell them which medicine you take, your current dose and when you last changed it, because the timing of a dose increase can be useful context.

If you have a known heart rhythm condition, heart disease or high blood pressure, say so during your consultation and at every review. Treatment decisions should reflect your full history, and that is exactly what a prescriber's review is for.

You can also report a suspected side effect yourself through the MHRA Yellow Card scheme, which collects reports to help monitor medicine safety.¹⁹ Reporting does not replace speaking to a clinician about your own care. Tell your prescriber about any new or lasting symptom, even if it is not on the leaflet's list of side effects.

09 · Mounjaro versus others

Is it different on Mounjaro, Wegovy or other GLP-1 medicines?

Mounjaro (tirzepatide) acts on GIP and GLP-1 receptors, while semaglutide, used in Wegovy and Ozempic, acts on GLP-1 alone. Ozempic is semaglutide licensed for type 2 diabetes — it is not a UK weight-loss medicine, and prescribing it privately for weight loss is off-label. Liraglutide is a daily injection supplied at 6mg/ml, unlike the once-weekly Mounjaro and Wegovy pens.

The headline Mounjaro trial result is about weight too. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² These are trial averages: individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

They describe weight outcomes. They are not a statement about your pulse, and nobody should read them as one.

If you are choosing between products, the more useful question is which suits your health history and goals. Our Wegovy pen page explains that option, and a prescriber can advise on the differences that matter for you, including any heart-related history.

10 · Does it need to change?

What if the change bothers you: adjusting or stopping

Never change or stop a prescribed medicine on your own because of a number on a watch. The right first move is to contact your prescriber, who can review your dose, your recent changes and your symptoms, and decide whether anything should be adjusted.

It helps to know how long the medicine stays in your body. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system — there is no way to speed this up, and nothing needs doing while it clears.¹ That means an effect would not vanish the day after you decide to stop, and it is one more reason to talk to a clinician rather than act alone.

Many people never need to change anything: the pulse settles, or turns out to reflect dehydration, caffeine or poor sleep. Where it does not settle, your prescriber has choices, and some will involve checking your blood pressure and overall health first. Our related page on whether Mounjaro can lower heart rate and the explainer on why a pulse increase might happen give more context on how clinicians think about it, and our overview of heart rate effects pulls the threads together.

11 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. Chest pain, fainting, a racing heart or swelling of the face, lips, tongue or throat also need medical help straight away. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹