Diarrhoea and constipation on Mounjaro are quite common, but these side effects don’t happen to everyone. In this article, you’ll learn how diarrhoea and constipation can develop because of Mounjaro and how to deal with it.
Three Key Takeaways
Diarrhoea and constipation are common side effects of Mounjaro, along with other digestive symptoms, like acid reflux and bloating.
Most symptoms improve with time and lifestyle adjustments, as your body gets used to treatment.
If diarrhoea goes on for longer than 7 days, contact your GP. If constipation continues for longer than 14 days without improvement or causes severe or persistent pain, speak to a clinician.
Does Mounjaro cause diarrhoea?
Yes, Mounjaro does cause diarrhoea, but not for everyone who takes it.
Two studies showed that around one in five people on Mounjaro get diarrhoea, making it the second most common side effect behind nausea.
This happens because Mounjaro slows down how fast your stomach empties and changes the way your gut processes food. Because of this, food and liquid can move differently through your intestines, which sometimes makes them speed up. That “faster movement” means less water is absorbed, leading to loose stools or diarrhoea.
While diarrhoea on Mounjaro is quite common and can last for several days, it’s usually mild or moderate and goes away on its own.
How to stop diarrhoea on Mounjaro
Most of the time, people recover from diarrhoea when taking Mounjaro without treatment within a few days. If you are worried about it or you’re struggling to manage it, our clinicians can help you prevent and stop it.
Make sure you drink plenty of water to prevent dehydration, as you’ll lose vital fluids in loose, watery stools. Severe dehydration can cause kidney problems and lead to hospital stays, so stay on top of your fluid intake. Sip fluids slowly and aim to get around 10 cups (4 pints) of water, squash, or herbal tea daily.
Stick to small, frequent meals and snacks, as this can help you avoid overloading your stomach. You might also benefit from cutting down your fibre intake, as some types can be difficult to digest. This can make diarrhoea worse.
You can choose low-fibre foods like:
White bread
Pasta
Noodles
Rice
Cooked vegetables with the skin removed
Skinless and cooked fruits
Fruit juice
Try the following soft foods, which can be easier to digest while your stomach is feeling sensitive:
Ice creams and sorbets
Jelly
Mashed potatoes
Milk puddings
Sorbets
White fish
Yoghurt
Over-the-counter (OTC) anti-diarrhoea medications, including loperamide (Imodium), are available at pharmacies, but you won’t usually need them.
When to speak to a doctor:
If you’re taking Mounjaro and have diarrhoea, the following symptoms are red flags that mean you should speak with a doctor:
Your watery stools happen frequently or are severe.
They last for more than a week.
You have blood in your stool. This may mean they’re dark or black.
You’re also vomiting and can’t keep fluids down.
You have an ongoing, severe bellyache.
You’ve unintentionally lost weight.
Diarrhoea occurs at night and disrupts your sleep.
You have symptoms of dehydration, such as passing less urine than usual or feeling drowsy, light-headed, and dizzy.
Does Mounjaro cause constipation?
Yes. People regularly experience constipation on Mounjaro. In two clinical trials, 15 out of 100 participants without diabetes and nine out of 100 with diabetes experienced Mounjaro-related constipation as a side effect.
This happens because Mounjaro slows digestion to make you feel fuller for longer. This effect can make constipation more likely, as food stays in the bowel for longer (sometimes several hours or days). During this time your body absorbs more water from the food, which can make your stools hard, dry, and difficult to pass.
Constipation is considered very common with Mounjaro, affecting more than 1 in 10 people who take it.
How to relieve constipation on Mounjaro
Diet and lifestyle changes, over-the-counter remedies, and taking the right preventive steps can all help you deal with constipation caused by Mounjaro. Like other common side effects, constipation typically improves within a few days on its own. However, if you’re finding constipation uncomfortable, changes to what you eat might help you go more regularly and feel better. Try:
Gradually including more high-fibre foods in your diet, like oats, whole bran, or linseed. These can add bulk to your stools and make them easier to pass.
Fruits containing sorbitol, a sugar alcohol that can have a laxative effect. These include apples, apricots, grapes, raspberries, and strawberries.
Staying hydrated with plenty of fluids and avoiding alcohol. Drinking fluids can help add moisture to hard, dry poops, but alcohol can have the opposite effect, causing dehydration.
Update your toilet habits
Changes to your daily toilet routine may also help. Try going to the toilet at the same time each day to establish a routine, andwhen you do, make sure you give yourself plenty of time to go. Do not pressure yourself. You should also consider resting your feet on a low stool with your knees raised above your hips.
Top tip! Listening to your urges is essential: try to find a toilet if you feel the need to go and never hold it in – unless you have to.
Try a laxative
If lifestyle and diet changes aren’t helping you go, you can ask a pharmacist for advice on laxatives like:
senna (Senokot)
bisacodyl or sodium picosulfate (Dulcolax)
ispaghula husk (Fybogel)
methylcellulose
lactulose (Duphalac, Lactugal)
macrogol (Movicol, Laxido, CosmoCol, Molaxole and Molative)
polyethylene glycol
These treatments help manage constipation in different ways. Some speed up your bowel movements, others draw water into your stools, and others make them bulkier. Your pharmacist can help you find the safest and most effective option, so be sure to speak to one before taking anything.
Change your lifestyle
Eating regularly throughout the day is a good way to prevent constipation. We also recommend getting regular exercise. Exercise helps with constipation as it speeds up how fast food goes through the large intestine. It also strengthens core muscles which help with bowel movements, and reducesstress, which can be a trigger for constipation.
When to speak to a doctor:
If you get constipation, see a doctor if the following symptoms develop:
Constipation doesn’t improve with treatment.
Constipation happens regularly.
You feel bloated often.
Your stool is bloody.
You’ve experienced unexpected weight loss.
You’ve noticed sudden changes in your bowel movements.
You also have bellyache.
If you feel constipated on Mounjaro, don’t stop taking it without first speaking to your GP.
“If you’re finding you’re experiencing uncomfortable changes to your toilet habits, like you’re going much more often or struggling to go at all - it may be your body getting used to the way Mounjaro changes how you digest food. This usually only lasts a few days and means your injections are working! You can manage these symptoms at home or with a little help from your pharmacist if they’re stopping you from going about your day. The important thing to remember is that these symptoms are usually nothing to worry about and will go away on their own.”
Constipation and diarrhoea on Mounjaro aren’t its only digestive side effects. People can also experience acid reflux, belly pain, bloating, belching, and passing wind.
Acid reflux
Mounjaro can cause the stomach to empty more slowly, which may lead to indigestion. This can cause heartburn, a burning sensation caused by stomach acid moving back up from your stomach to your chest area. This is also known as acid reflux.
Home remedies might include:
Eating smaller meals more often instead of large meals three times daily
Avoiding meals within three or four hours of bedtime
Not wearing clothes that are tight around the waistline
Speaking to your GP about antacids or alginate, which can help reduce heartburn
Trapped wind, passing more wind (including belching), and bloating
Mounjaro slows down how your stomach works, causing food to stay there for longer. This can create more gas as it breaks down this food. Your stomach might feel full, sore, or bloated, and you may burp or pass wind more than usual.
For relief, you can try:
Regular exercise
Staying hydrated
Eating high-fibre foods (if you’re also constipated on Mounjaro)
Massaging your belly from right to left to release wind
Avoiding fizzy drinks and gassy foods like beans, lentils, or cabbage
Steering clear of large meals before bed
Reducing your intake of spicy, fatty, sugary, or processed foods
Speaking to a pharmacist, who may recommend OTC medications like Buscopan or Mebeverine
Stomach pain
Stomach pain can also be a symptom of the bloating Mounjaro can cause. You can try managing this at home by:
Drinking plenty of fluids
Sitting upright to prevent stomach acid from moving up
Taking a warm bath
Avoiding the foods above that worsen trapped wind and sticking to bland foods like bananas, rice, crackers, boiled potatoes, and rice
Using OTC pain relief such as paracetamol
Frequently asked questions
Do you need to take Mounjaro on an empty stomach?
No. You can take Mounjaro on an empty stomach or after eating without affecting its safety or effectiveness.
Can Mounjaro cause stomach ulcers?
There’s no evidence that suggests Mounjaro directly causes stomach ulcers.
Does Mounjaro cause stomach pain after eating?
While Mounjaro can cause stomach pain, it’s not specifically after eating.
If you feel stomach pain after eating on Mounjaro, it may be due to delayed stomach emptying.
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