Thrush on your tongue is a fungal infection caused by an overgrowth of Candida, a type of yeast that normally lives in your mouth in small amounts. It shows up as creamy white, slightly raised patches on the tongue and inner cheeks that look like cottage cheese. These patches can hurt, and if you lightly scrape or brush them, they reveal a reddened, tender area underneath that may bleed slightly.
Thrush is uncommon in healthy adults. It mostly affects babies under one month old and older adults, both of whom have weaker immune defenses. If you’re a generally healthy adult noticing these white patches, something is likely tipping the balance of microorganisms in your mouth.
What It Looks Like
The hallmark of oral thrush is white, raised lesions on the tongue or inner cheeks. They have a distinct cottage cheese texture, slightly bumpy and soft. You might also notice them on the roof of your mouth or along your gums. The patches themselves don’t always hurt at first, but as the infection progresses, they can become sore, especially when eating acidic or spicy foods.
If you try to wipe or scrape the patches away (or even just brush your teeth normally), you’ll often see raw, reddish tissue underneath that bleeds a little. This is one of the clearest signs that what you’re seeing is thrush rather than a normal coating on the tongue. Some people also experience a cottony feeling in the mouth, loss of taste, or mild cracking at the corners of the lips.
Why It Happens
Candida lives in most people’s mouths without causing problems. It only becomes an infection when something disrupts the normal balance of bacteria and yeast. Several common triggers can set this off:
- Antibiotics. They kill bacteria throughout the body, including the beneficial bacteria in your mouth that normally keep Candida in check. A course of antibiotics is one of the most common reasons otherwise healthy adults develop thrush.
- Inhaled corticosteroids. If you use a steroid inhaler for asthma or COPD, traces of the medication settle on your tongue and throat and suppress local immune defenses. This is a well-known and preventable trigger.
- Diabetes. Poorly controlled blood sugar means higher sugar levels in your saliva, which feeds Candida and encourages it to grow.
- Dry mouth. Saliva helps control yeast. Anything that reduces saliva production, whether it’s a medication side effect or a condition like Sjögren’s syndrome, raises your risk.
- Weakened immunity. HIV/AIDS, cancer treatments, organ transplant medications, and drugs like prednisone all suppress the immune system enough for Candida to take over.
- Dentures. Upper dentures in particular create a warm, moist environment against the palate where yeast thrives, especially if they don’t fit well or aren’t cleaned regularly.
- Smoking. Tobacco use independently increases the risk of oral thrush.
How It’s Diagnosed
Most of the time, a doctor or dentist can diagnose thrush just by looking at it. The appearance is distinctive enough that no testing is needed for a straightforward case.
When there’s any uncertainty, or if the infection keeps coming back, a simple lab test can confirm it. A doctor lightly scrapes a small sample from the affected area and places it on a slide with a potassium hydroxide solution. This solution dissolves normal skin cells but leaves fungal cells intact, making them visible under a microscope. The scraping can be mildly uncomfortable if the area is already sore, but the test itself is quick.
Treatment and Recovery
Mild thrush is typically treated with a topical antifungal, a liquid suspension that you swish around your mouth and then swallow. Treatment usually lasts one to two weeks. For mild cases, a dissolving lozenge used several times a day is another option. Both work by killing the yeast directly on contact with the tissue in your mouth.
If the infection is more severe or doesn’t respond to topical treatment, your doctor may prescribe an oral antifungal pill that works through your bloodstream. This is more common in people with weakened immune systems, where the infection can be stubborn or spread to the esophagus, causing pain with swallowing.
Most people start to feel improvement within a few days of starting treatment, and the white patches gradually clear over the course of one to two weeks. If you’re immunocompromised, treatment may take longer and the infection is more likely to return.
What You Can Do at Home
A saltwater rinse can help soothe irritated tissue while you’re being treated. Dissolve about half a teaspoon of salt in one cup of warm water, swish gently, and spit. This won’t cure the infection on its own, but it can ease discomfort and help keep the area clean.
There’s growing interest in probiotics for oral thrush. A systematic review of clinical trials found that probiotics, particularly strains of Lactobacillus, reduced the odds of oral Candida overgrowth by about 47% in randomized controlled trials. Some studies used probiotic lozenges or capsules, others used dairy products like yogurt or cheese. The evidence is promising enough to suggest that eating unsweetened yogurt with live cultures or taking a probiotic supplement may help support recovery alongside prescribed treatment, though probiotics alone aren’t a reliable substitute for antifungal medication.
Preventing Thrush if You Use an Inhaler
If you use a corticosteroid inhaler for asthma or COPD, thrush prevention comes down to a simple habit: rinse your mouth thoroughly with water or brush your teeth immediately after every dose. This removes medication residue before it has a chance to suppress your mouth’s local defenses.
Using a spacer device with your inhaler also helps. A spacer is a tube that attaches to the inhaler and reduces the amount of medication that lands in your mouth and throat, directing more of it into your lungs where it’s actually needed. If you’re getting recurrent thrush despite rinsing, ask your doctor about adding a spacer or adjusting your inhaler type.
When Thrush Keeps Coming Back
Recurrent thrush in an adult, meaning multiple episodes over several months, often signals an underlying issue worth investigating. Undiagnosed or poorly controlled diabetes is one of the most common culprits. In some cases, recurrent oral thrush is the first visible sign of a weakened immune system, including in people who don’t yet know they have HIV.
If you’re getting thrush repeatedly and don’t have an obvious trigger like inhaler use or recent antibiotics, your doctor will likely want to check your blood sugar levels and possibly screen for immune-related conditions. Addressing the underlying cause is the only way to stop the cycle, since antifungal treatment alone will keep clearing each episode without preventing the next one.