Can You Smoke Weed on Mounjaro? UK Guidance (October 2026)

01 · The short answer

Can you smoke weed while on Mounjaro?

Cannabis is not listed in the Mounjaro patient leaflet. The Summary of Product Characteristics and the patient leaflet are the authorities on interactions, and they are where your prescriber will look.¹¹³

Cannabis is also a controlled drug in the UK unless it has been lawfully prescribed.

02 · What you are really deciding

The decisions you are actually facing

Most readers are weighing up a practical question: will weed make my treatment harder or less effective? There are three angles worth thinking about.

• Appetite. Mounjaro works partly by helping you feel fuller sooner and less hungry between meals.¹ Cannabis is widely associated with increased appetite. If you notice strong hunger after using it, that works against the point of treatment, even if it is not a drug interaction in the pharmacological sense.
• Stomach comfort. Mild nausea is among the commonest early effects of Mounjaro and usually settles.¹ If you already feel queasy after an injection, adding anything else that unsettles your stomach is unlikely to help.
• Honesty with your prescriber. Your prescriber can only advise on what they know. Mentioning cannabis lets them judge whether it matters for your medical history.

If you want a wider read on this theme, our guide to Mounjaro and smoking covers tobacco and other smoked substances, and our page on smoking while on treatment takes a similar practical view.

03 · What to do next

What to do if you use cannabis and want to start

Start the conversation early. Our consultation is free, and your answers are reviewed by a GPhC-registered prescriber, who can discuss anything relevant to your health.

04 · What the label says

What the label says about cannabis

Cannabis is not listed in the Mounjaro patient leaflet.

The patient leaflet and the Summary of Product Characteristics are the documents to check, and your prescriber or pharmacist can interpret them for your circumstances.¹¹³

If you notice a new symptom after using cannabis while on treatment, discuss it with your prescriber. You can also report suspected side effects through the MHRA Yellow Card scheme, which is how real-world safety signals are gathered in the UK.¹⁹

05 · How Mounjaro works

How Mounjaro works on appetite

Tirzepatide activates 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. In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.¹

This is why the appetite question matters. The treatment is designed to quieten hunger so that eating less feels manageable. If something else in your routine regularly sends you towards the kitchen, that is worth noticing, whatever the cause.

It also explains why the medicine is paired with lifestyle changes rather than replacing them. 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 Trial averages do not predict your own result, and the trial measured people following a reduced-calorie diet, not people free to eat whatever appetite suggests.

06 · Appetite and the munchies

Appetite, cravings and the "munchies"

The main practical concern is not toxicity but goals. Cannabis is commonly associated with a surge in appetite, often for snacky, calorie-dense food. Mounjaro is meant to make you feel fuller and less hungry between meals.¹ If you use weed in the evening and find yourself raiding the cupboards, you may feel the medicine is working less well than it should.

It varies from person to person. What helps is awareness. If you do use cannabis, notice what happens to your eating afterwards and be honest in your reviews.

Some practical ideas people find helpful, none of which are medical instructions:

• Keep protein-rich, filling foods in the house rather than ultra-processed snacks.
• Decide in advance what you will eat if hunger appears, so you are not improvising.
• Keep a simple note of when you use cannabis and how your appetite felt the next day.
• Raise any pattern at your monthly review so your prescriber has the full picture.

If you want to understand the other direction, our pages on weed and appetite suppression and whether weed can suppress appetite explore the common confusion, and our explainer on whether smoking suppresses appetite looks at smoking more generally.

07 · Nausea and stomach upset

Nausea, stomach upset and timing

Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹ The starting weeks on 2.5mg are about adjustment, and experiences differ widely.

Because your stomach is already adapting, it is sensible to avoid piling extra variables on top, especially in the days right after an injection or a dose increase. If you feel unwell and also used cannabis, it becomes hard to tell which caused what. That makes it harder for your prescriber to help you.

Mounjaro is injected once a week on the same day, at any time of day, with or without food.¹ Many people choose a weekend morning so early side effects fall on days off.

If nausea or vomiting is persistent or you cannot keep fluids down, contact your clinical team, as dehydration needs medical help straight away.

08 · Smoking and other medicines

Other substances and medicines with Mounjaro

People often ask what they should avoid while taking Mounjaro and what drugs interact with it. The reliable answer sits in the leaflet and the Summary of Product Characteristics, and your prescriber should always know every medicine you take, including those bought over the counter.¹¹³

Two points are worth stating clearly. Mounjaro slows stomach emptying, which can reduce how well oral contraceptive pills are absorbed. The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹ And if you take insulin or sulfonylureas, doses may need adjusting because of the risk of low blood sugar. Neither point is about cannabis, but both show why full disclosure matters.

The same logic applies to anything else you use: tobacco, vapes, alcohol, supplements or recreational drugs. Tell your prescriber.

Be cautious with online lists of "things to avoid". Many mix up tirzepatide with other medicines or repeat advice from other countries. When in doubt, the leaflet and your prescriber outrank a forum thread.

09 · Weight loss while using weed

Can you still lose weight if you smoke weed?

Weight loss on Mounjaro is gradual by design. The early weeks on 2.5mg are an adjustment phase and losses are usually modest, with most measurable progress building from 5mg onward, month by month.

Trials measured results at 72 weeks, so think in months, not days, and judge progress by trend rather than individual weigh-ins.² Early loss includes water weight, so single readings mislead.

Your response is reviewed by your prescriber. If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, they will discuss whether continuing or stopping is right for you.¹ If cannabis-driven eating is part of why progress is slow, that is exactly the sort of thing to say out loud at a review. It is a solvable problem, not a failure.

Treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them. Anything that regularly undermines the diet side will show up in the trend.

10 · Heavy use and cutting down

Is daily use heavy, and should you cut down?

If you use it daily, or feel you rely on it to sleep, relax or manage stress, that is worth discussing with a clinician regardless of Mounjaro.

Some people use the start of treatment as a moment to review habits generally. If you decide to reduce or stop, it is sensible to talk to your GP or a drug and alcohol support service first, especially if you use cannabis regularly, because stopping suddenly can be unpleasant for some people. Your GP or a local service can help without judgement.

None of this is a condition of getting treatment from us. Your consultation is reviewed by a GPhC-registered prescriber who looks at your overall suitability, and honest answers help them do that properly.

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. 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

12 · Talking to your prescriber

How to raise it with your prescriber

Be direct and specific. Saying "I sometimes use cannabis in the evenings" gives far more to work with than staying silent. Prescribers hear this regularly, and their job is to keep you safe and make treatment work.

Useful things to mention:

• How often you use cannabis and in what form, such as smoked or edible.
• Whether you notice more hunger or snacking afterwards.
• Any nausea, stomach upset or dizziness you link to it.
• Any other medicines or supplements you take.

With us, ongoing monthly reviews, dose-titration and follow-up assessments are handled by the prescribing team, and repeat orders re-check suitability. If something unexpected happens, you can also report it through the Yellow Card scheme.¹⁹ Support is available Monday to Friday, 9am to 5pm, at support@everydaymeds.co.uk or 0333 207 0413.

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.