What Are the Chances of Getting Gastroparesis From Tirzepatide? (October 2026)

01 · The honest answer

So what are the chances?

Tirzepatide activates two gut-hormone receptors, 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 Slowed emptying is part of the design, and it is one reason most people feel fuller sooner and less hungry between meals.

The UK Mounjaro patient leaflet lists slower stomach emptying as an uncommon side effect (up to 1 in 100 people); very common effects (more than 1 in 10) include feeling sick, diarrhoea, being sick, stomach pain and constipation.

02 · Two different things

Slowed stomach emptying is not the same as gastroparesis

Slower stomach emptying is the intended pharmacological action of tirzepatide, while gastroparesis is a medical diagnosis made by a clinician.

The first is an effect of the medicine on a healthy digestive system, and it is part of why the medicine supports a reduced-calorie diet. The second is a clinical condition that needs proper assessment. A person who feels fuller for longer after a meal is not necessarily developing it, and a clinician is the right person to tell the difference.

If you are worried about your symptoms, our guide to gastroparesis and Mounjaro and our wider explainer on GLP-1 medicines and gastroparesis give more detail, and your prescriber can review you directly.

03 · Your next step

What to do if you are worried

If you are worried, talk to a prescriber before you start rather than after a problem appears. A prescriber will assess your BMI, medical history and current medicines before deciding whether Mounjaro is suitable.¹ Mention any existing digestive condition, past stomach problems and every medicine you take, including over-the-counter ones.

If you are already taking tirzepatide and notice a new symptom that concerns you, contact your prescriber and report it through the Yellow Card scheme. If you have severe, persistent stomach pain, with or without vomiting, stop using Mounjaro and get medical help straight away.¹⁹ Reports help regulators monitor safety across the UK. Do not wait for a symptom to settle on its own if it worries you.

04 · Where to check

Where to check side effect frequencies

The authoritative places to check are the Mounjaro KwikPen Summary of Product Characteristics and the Patient Information Leaflet, both published on the electronic medicines compendium.¹¹³ The leaflet is written for patients and lists side effects in plain language.

When you read it, look for three things:

• which digestive effects are listed and how often each is said to occur;
• which symptoms the leaflet tells you to raise with a doctor or pharmacist;
• any warnings about other medicines or existing conditions that apply to you.

Bring anything you are unsure about to your prescriber.

05 · How the medicine works

How tirzepatide affects digestion

Tirzepatide is the first treatment of its kind to activate both GIP and GLP-1 receptors at once.¹ These two natural gut hormones help regulate appetite, slow how quickly the stomach empties and improve how the body responds to insulin.

In practice, most people feel fuller sooner and less hungry between meals. That supports the reduced-calorie diet the medicine is designed to work alongside. The dual action distinguishes it from single-action GLP-1 medicines such as semaglutide (Wegovy and Ozempic).

Because the effect on the stomach is part of the mechanism, it is also the reason prescribers ask about your digestive history. If you want to know where the active ingredient comes from, see what Mounjaro is derived from.

Tirzepatide has a half-life of about five days. After a final dose it takes roughly 4 to 5 weeks to clear the system, and there is no way to speed this up. Nothing needs doing while it clears.¹ That is worth knowing if you ever stop treatment because of a symptom: speak to your prescriber rather than waiting to see what happens.

06 · Related safety questions

Other safety questions people ask

• Can you get pancreatitis from Mounjaro? Our dedicated page explains what to raise with your prescriber.
• Thyroid cancer and Mounjaro is covered separately.
• Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly.

Discuss any new symptom with your prescriber and report it via Yellow Card.

07 · Who it is for

Who Mounjaro is licensed for

Mounjaro is licensed for weight management in adults with a BMI of 30 or above, or a BMI between 27 and 30 with at least one weight-related condition. Examples include high blood pressure, high cholesterol, obstructive sleep apnoea, cardiovascular disease, prediabetes or type 2 diabetes. It must be used alongside a reduced-calorie diet and increased physical activity.¹

In SURMOUNT-1, which involved 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. The comparison group on lifestyle changes alone lost 3.1%.²

These are trial averages and individual results vary. For someone starting at 100 kg, 20.9% is about 21 kg. Your own result depends on many things, and the trial averages do not predict it.

08 · NHS and private

NHS and private access

Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition. The NHS primary-care rollout began in June 2025 with the highest-need groups first, initially BMI 40+ with four or more qualifying conditions.⁴⁶

Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment.

If you go privately, check the pharmacy is registered. We are registered with the GPhC under number 9012878, and you can verify that on the GPhC register.¹²

09 · 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. 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

Mounjaro (tirzepatide) is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary. This page is information, not a substitute for medical advice.