The Ugly Side of Weight-Loss Drugs: Rotten Breath, Damaged Teeth, and Dry Mouth

Gizmodo

08-06-2025

Ozempic and Wegovy have been hailed as wonder drugs when it comes to weight loss. But as the drug has become more widely used, a number of unintended side-effects have become apparent—with the weight loss drug affecting the appearance of everything from your butt to your feet.
'Ozempic face' is another commonly reported consequences of using these popular weight loss drugs. This is a sunken or hollowed out appearance the face can take on in people taking weight loss drugs. It can also increase signs of ageing—including lines, wrinkles and sagging skin.
This happens because semaglutide (the active ingredient in both Ozempic and Wegovy) isn't localised to act just on the fat we want to lose. Instead, it targets all of our body's fat—including in the face.
But it isn't just the appearance of your face that semaglutide affects. These drugs may also affect the mouth and teeth, too. And these side-effects could potentially lead to lasting damage.
Dry mouth
Semaglutide effects the salivary glands in the mouth. It does this by reducing saliva production (hyposalivation), which can in turn lead to dry mouth (xerostomia). This means there isn't enough saliva to keep the mouth wet.
It isn't exactly clear why semaglutide has this effect on the salivary glands. But in animal studies of the drug, it appears the drug makes saliva stickier. This means there's less fluid to moisten the mouth, causing it to dry out.
GLP-1 receptor agonist drugs (such as semaglutide) can also reduce water intake by affecting areas in the brain responsible for thirst. Low fluid intake further reduces saliva production, and may even cause the saliva to become thick and frothy and the tongue to become sticky.
Bad breath
One other commonly reported unwanted effect by semaglutide users is bad breath (halitosis). When there's less saliva flowing through the mouth, this encourages bacteria that contribute to bad breath and the formation of cavities to thrive. These bacterial species include Streptococcus mutans and some strains of Lactobacillus.
Another species that has been shown to thrive in conditions where saliva is reduced is Porphyromonas gingivalis. This bacteria is a significant contributor to the production of volatile sulphur compounds, which cause the foul odours characteristic of halitosis.
Another factor that might explain why semaglutide causes bad breath is because less saliva being produced means the tongue isn't cleaned. This is the same reason why your 'morning breath' is so bad, because we naturally produce less saliva at night. This allows bacteria to grow and produce odours. Case report images show some people taking semaglutide have a 'furry'-like or coated appearance to their tongue. This indicates a build up of bacteria that contribute to bad breath.
Tooth damage
One of the major side-effects of Ozempic is vomiting. Semaglutide slows how quickly the stomach empties, delaying digestion which can lead to bloating, nausea, and vomiting.
Repeated vomiting can damage the teeth. This is because stomach acid, composed primarily of hydrochloric acid, erodes the enamel of the teeth. Where vomiting occurs over a prolonged period of months and years the more damage will occur. The back surface of the teeth (palatal surface) closest to the tongue are more likely to see damage–and this damage may not be obvious to the sufferer.
Vomiting also reduces the amount of fluid in the body. When combined with reduced saliva production, this puts the teeth at even greater risk of damage. This is because saliva helps neutralise the acid that causes dental damage.
Saliva also contributes to the dental pellicle—a thin, protective layer that the saliva forms on the surface of the teeth. It's thickest on the tongue-facing surface of the bottom row of teeth. In people who produce less saliva, the dental pellicle contains fewer mucins—a type of mucus which helps saliva stick to the teeth.
Reducing the risk of damage
If you're taking semaglutide, there are many things you can do to keep your mouth healthy.
Drinking water regularly during the day can help to keep the oral surfaces from drying out. This helps maintain your natural oral microbiome, which can reduce the risk of an overgrowth of the bacteria that cause bad breath and tooth damage.
Drinking plenty of water also enables the body to produce the saliva needed to prevent dry mouth, ideally the recommended daily amount of six to eight glasses. Chewing sugar-free gum is also a sensible option as it helps to encourage saliva production. Swallowing this saliva keeps the valuable fluid within the body. Gums containing eucalyptus may help to prevent halitosis, too.
There's some evidence that probiotics may help to alleviate bad breath, at least in the short term. Using a probiotic supplements or consuming probiotic-rich foods (such as yoghurt or kefir) may be a good idea.
Practising good basic oral hygiene, tooth brushing, reducing acidic foods and sugary drinks and using a mouthwash all help to protect your teeth as well.
Women are twice as likely to have side-effects when taking GLP-1 receptor agonists–including gastrointestinal symptoms such as vomiting. This may be due to the sex hormones oestrogen and progesterone, which can alter the gut's sensitivity. To avoid vomiting, try eating smaller meals since the stomach stays fuller for longer while taking semaglutide.
If you are sick, don't immediately brush your teeth as this will spread the stomach's acid over the surface of the teeth and increase the risk of damage. Instead, rinse your mouth out with water or mouthwash to reduce the strength of the acid and wait at least 30 minutes before brushing.
It isn't clear how long these side effects last, they'll likely disappear when the medication is stopped, but any damage to the teeth is permanent. Gastrointestinal side-effects can last a few weeks but usually resolve on their own unless a higher dose is taken.
Adam Taylor, Professor of Anatomy, Lancaster University. This article is republished from The Conversation under a Creative Commons license. Read the original article.