Does Mounjaro cause bad breath? Understanding what’s behind 'Mounjaro breath'

Noticed a slightly (or severely) fishy smell coming out of your mouth since you started using Mounjaro? You might be experiencing ‘Mounjaro breath’ – the lesser-known but no less unpleasant cousin to the well-documented ‘Ozempic breath’.

Even though it might be a little embarrassing, you’ll be glad to know Mounjaro breath is both fairly common and potentially avoidable. Here’s everything you need to know. 

What is 'Mounjaro bad breath'?

Mounjaro bad breath, or simply Mounjaro breath, is the unpleasant fishy odour or general bad breath smell that some people get when they’re taking Mounjaro. 

Bad breath, also known by its clinical name halitosis, isn’t one of the listed side effects of Mounjaro, but that’s not to say it doesn’t affect people. Many patients report that their breath is suddenly a lot more noticeable, particularly when they burp. One recent study found that belching affected almost 9% of semaglutide patients, which often brings up an off-smelling odour from your insides.

Evidence is also emerging on the full spectrum of side effects when using weight loss injections like Mounjaro, and studies are still being done to investigate those that aren’t as frequent as vomiting, diarrhoea and nausea [1]. So while bad breath isn’t necessarily a recognised side effect right now, it may be added in time.

Why does Mounjaro cause bad breath?

There are a few possible explanations.

The first is to do with how the medication affects your digestive system. Mounjaro works by gastric emptying, which in simple terms means it slows down the time it takes for food to make its way through your stomach. While on one hand, this makes you feel fuller for longer (consequently making you eat less), on the other, it means food takes longer to break down. 

When food is sitting in your stomach, gut bacteria get to work fermenting some of the proteins in it and pumping out hydrogen sulphide gas, which is then released from your body as a burp. The longer the food sits, the longer it has to ferment and produce gas, potentially making your belches smell a lot worse. If you’re eating lots of protein, which you may be on a weight loss diet, the bacteria have more protein to feast on. This could very easily intensify your burps.

Mounjaro may also make burps particularly bad because it’s a dual-action medication. This means it could slow down digestion even more than other weight loss injections like Ozempic and Wegovy, which only have one active ingredient.

Another possibility is that bad breath is caused by dry mouth, a common side effect of taking Mounjaro. When you’ve got less saliva circulating around your mouth, it creates an ideal environment for certain bacteria, specifically, the ones related to bad breath, to thrive. Less saliva also means your tongue isn’t getting cleaned as efficiently, further enabling these bacteria to grow [2].

Can Mounjaro cause a bad taste in the mouth?

Some users also report a bad taste in their mouth, either directly after injecting the medication or as an ongoing side effect that lingers throughout their Mounjaro journey.

It could be a metallic or bitter aftertaste, or a sensation where some foods taste different. Fatty and sugary foods, for instance, are often a lot less appealing among those taking the medication. 

Scientists aren’t sure exactly why this happens, but one theory is that weight loss injections like Mounjaro affect taste receptors, changing how the brain processes flavours [3][4].

One very important thing to note is that a metallic taste in the mouth may be the result of kidney problems – a rare but serious side effect of taking Mounjaro. If you experience this alongside other symptoms such as reduced urination, sudden bruising, swelling in different parts of your body or kidney pain, contact your doctor straight away.

Do weight loss injections cause bad breath?

Mounjaro isn’t the only weight loss injection linked to bad breath. Even though other injectable weight loss drugs like Ozempic and Wegovy contain a different active ingredient (semaglutide), they can still have the same effect.

‘Ozempic breath’ is a particularly common complaint, but some Wegovy users also report that their breath has started smelling a little off since starting the medication. Several users also say there’s a funny taste in their mouth, much like with Mounjaro.

Why does my breath stink on semaglutide?

The things that cause bad breath while taking semaglutide medications are much the same as those linked to Mounjaro: slowed digestion leading to foul-smelling burps; dry mouth allowing bacteria to grow; and dietary changes that increase gas production. That being said, bad breath may not be as strong or frequent as with Mounjaro, because these weight loss injections are single-action medications.

Other oral health issues linked to weight loss injections

Besides bad breath, weight loss injections have the potential to cause several other oral hygiene problems, such as:

• Sensitive teeth: Vomiting is one of the most common side effects associated with Mounjaro. Vomit is highly acidic, and it can slowly cause enamel erosion on your teeth. You might notice that your teeth then become more sensitive, particularly to hot and cold
• Tooth decay: Eventually, side effects like vomiting and dry mouth may lead to tooth decay. When the acid in vomit wears away your tooth enamel, it makes cavities more likely, while dry mouth decreases saliva production – a vital defence for protecting your teeth from acid and bacteria
• Fractures: Enamel erosion can also make your teeth weaker, possibly causing them to fracture and chip
• Gum problems: Once again, the lack of saliva associated with dry mouth means more bacteria and food particles are left in your mouth. This can potentially increase your risk of gum disease, along with eventual gum recession

What can be done about Mounjaro-related bad breath and burps?

You might find that Mounjaro breath settles down as your body adjusts to the medication. In the meantime, or if it’s just not budging, there are a few things you can do.

Make mints your friend

If you’re caught short with bad breath, mints or gum may provide temporary relief. Have a stash with you at all times so you can freshen your breath on the spot.

You could also try a mouthwash, specifically one targeted at treating halitosis.

Minimise intake of fatty and sulphur-y foods

Fatty foods are harder to digest, meaning they stay in your stomach for a lot longer. As we know, this ups your chances of getting those sulphur-scented burps that contribute to bad breath. 

You might also want to avoid overconsuming foods that are particularly high in sulphur, like meat, fish, chicken, eggs, legumes, and vegetables like onions, garlic, broccoli, Brussels sprouts and asparagus.

Degas your tummy

A build-up of wind in the stomach is more likely to result in belching. Try different remedies that may reduce gas, like peppermint tea, ginger or even a non-prescription medicine.

Eat smaller meals

Keeping your portion sizes small and eating frequent meals throughout the day, rather than a few big meals, may also help. These are easier for your body to digest and lower the likelihood of food sitting in your stomach for extended periods and turning into burps.

Stay hydrated

Drinking lots of water has plenty of benefits, especially when it comes to combating Mounjaro breath. For one, it supports your digestive tract and allows it to pass food more efficiently. Adequate hydration can also prevent dry mouth, which is a known factor in bad breath.

How to reduce your risk of Mounjaro breath

You might not be able to avoid Mounjaro breath entirely, but there may be steps you can take to lower your chances.

Increase your dosage gradually

There’s a good reason why you should only increase your Mounjaro dosage every four weeks. It gives your body the best chance to adjust to the medication and lowers the risk of side effects. This applies to avoiding bad breath, too. If you want to minimise discomfort, stick to the recommended dosing schedule and allow your body to adapt slowly.

Keep up a strong oral care routine

Good oral hygiene can remove a lot of the bacteria that may contribute to bad breath. UK health bodies recommend brushing your teeth twice daily for at least two minutes each session, and using a toothpaste with fluoride [5].

Flossing after meals or at least daily can also help, as can using your toothbrush or a tongue scraper on your tongue to get rid of food particles and bacteria. 

Pack your diet with whole and low-sulphur foods

Instead of high-fat and high-sulphur foods, try and pack your diet with lean proteins, fruits and low-sulphur vegetables such as courgettes, carrots and sweet potato.

You should also prioritise fibre, which keeps your digestion running smoothly and encourages regular bowel movements, which again may reduce the chances of build-up and bloating.

High-fibre foods to incorporate into your diet include whole grains, raw nuts and seeds, and those low-sulphur vegetables we mentioned earlier.

Should I see a dentist?

If you’re experiencing new or worsening bad breath, tooth sensitivity, gum problems, noticeable enamel erosion or other persistent issues with your oral hygiene while taking Mounjaro, you may want to pay a visit to your dentist. They can identify the issue and figure out a solution to protect your oral health when you’re on the medication.

Lose weight with Juniper

If you’re looking to lose weight, Juniper could be the solution you’re after.

Juniper's Weight Loss Reset Programme combines weight loss medication with dietitian-led health coaching and tracking, so you can lose weight and reach your goals for good.

Kickstart your weight loss journey with Wegovy or Mounjaro, two groundbreaking weight loss medications that mimic the GLP-1 and GIP hormones, respectively, to help control cravings, delay stomach emptying, and keep you feeling fuller for longer. These clinically backed treatments help members experience up to 20% body weight loss.

Plus, we have a team of expert dietitians and health coaches you can consult with to help you work through any challenges you're experiencing during your weight management journey. This approach sets you up for sustained weight loss, rather than a quick-fix solution.

This means you can continue to enjoy the things you love in moderation without ever feeling deprived.

Ready to see if Juniper is right for you? You can check your eligibility here.

Image credit: Pexels