Oral Thrush: Causes, Symptoms & Treatment
White patches, soreness and altered taste — what causes oral thrush, how it is treated, and the safety points that decide which medicine you should use.
Part of the Complete Thrush Guide.
Key fact: Oral thrush wipes away to leave a red, tender base — that is what distinguishes it from a coated tongue or leukoplakia. In adults it almost always has a trigger worth finding: a steroid inhaler used without rinsing, dentures worn overnight, a dry mouth, antibiotics or raised blood glucose.
What oral thrush is
Oral thrush is a Candida infection of the mouth and throat. The same yeast lives harmlessly in most people’s mouths; it becomes an infection when something tips the balance — a change in immunity, a dry mouth, a steroid inhaler, dentures, or a course of antibiotics.
It is common at both ends of life: in babies, whose immune systems are still developing, and in older adults, particularly denture wearers. In between, it usually points to an identifiable trigger, and finding that trigger matters as much as treating the infection.
What it looks and feels like
- White or creamy patches on the tongue, inner cheeks, gums or roof of the mouth
- Patches that leave a red, sometimes bleeding area when wiped or scraped
- Soreness or a burning sensation, and a loss or change of taste
- Cracking at the corners of the mouth (angular cheilitis)
- An unpleasant taste or bad breath
- Discomfort with dentures, or redness on the palate beneath them
- In babies: white patches inside the mouth, sometimes with reluctance to feed
Pain or difficulty swallowing needs assessment. It can mean the infection extends into the oesophagus, which is more common in people who are immunocompromised and needs systemic treatment rather than a topical gel.
Why it happens
Inhaled corticosteroids
The most common avoidable cause in adults. Steroid residue settles in the mouth and suppresses local immunity. Rinsing and gargling with water after every dose, and using a spacer, substantially reduces the risk.
Dentures
Ill-fitting or overnight-worn dentures create a warm, sheltered surface for Candida. Removing them at night and cleaning them properly is treatment as much as prevention.
Dry mouth
Saliva is protective. Medicines that dry the mouth, dehydration, mouth-breathing and radiotherapy to the head and neck all raise the risk.
Antibiotics
Broad-spectrum antibiotics disturb the normal oral bacteria that keep Candida in check — see thrush after antibiotics.
Diabetes
Raised blood glucose favours Candida at every site. Recurrent oral thrush in someone not known to have diabetes deserves a blood glucose check — see thrush and diabetes.
Reduced immunity
Chemotherapy, systemic steroids, HIV and other immunosuppression. Extensive or repeatedly recurring oral thrush in an otherwise healthy adult warrants investigation.
Smoking and a high-sugar diet both contribute. Unlike vaginal thrush, oral thrush in adults is not contagious in ordinary social contact.
Treatment
| Treatment | How it is used | Notes |
|---|---|---|
| Miconazole oral gel | Applied to the affected areas after meals, four times daily, and continued for about a week after symptoms clear | First-line for most adults. Hold in the mouth rather than swallowing immediately. Available as Daktarin oral gel |
| Nystatin suspension | Swilled around the mouth four times daily after food, and continued for 48 hours after the patches resolve | Useful where miconazole is unsuitable, including for people on warfarin. Available as Nystan oral suspension |
| Oral fluconazole | A course of capsules over one to two weeks | For extensive infection, symptoms reaching the throat, or where topical treatment has failed — and usually first choice in immunocompromised people |
Two safety points that matter with miconazole gel. It interacts significantly with warfarin, raising the risk of bleeding, and with some statins — tell the pharmacist what you take. And it is not suitable for babies under four months because of the risk of choking; a baby that age with suspected thrush should be seen by a GP.
Alongside medication: clean dentures thoroughly and leave them out overnight, rinse after every inhaler dose, keep the mouth moist, brush twice daily with a soft brush, and stop smoking if you can. If symptoms have not improved after a week of treatment, see a GP rather than continuing.
Babies and breastfeeding
Oral thrush is common in young babies and is not dangerous. It appears as white patches inside the mouth that do not wipe away like milk residue does, and it is treated with an antifungal gel or suspension prescribed for the baby’s age. Babies under four months should be seen rather than treated from the pharmacy shelf.
In breastfed babies, thrush frequently passes back and forth between the baby’s mouth and the nipple, causing sore, cracked or burning nipples alongside the baby’s symptoms. Both need treating at the same time or neither clears, and this is a conversation for your midwife, health visitor or GP.
When to seek help
- No improvement after a week of treatment
- Pain or difficulty swallowing, or symptoms extending into the throat
- A baby under four months old with suspected thrush
- Repeated episodes with no obvious cause
- You are immunocompromised or having chemotherapy
- A mouth ulcer or white patch that does not clear after treatment — this needs dental or medical review rather than more antifungal
Worth knowing: not every white patch in the mouth is thrush. Leukoplakia, lichen planus, geographic tongue and a coated tongue can all look similar, and true thrush wipes away to leave a red, tender base. A patch that will not shift with treatment should be examined.
Frequently Asked Questions
What does oral thrush look like?
White or creamy patches on the tongue, inner cheeks, gums or roof of the mouth, which wipe away to leave a red and sometimes bleeding area underneath. That last feature is the most useful distinguishing sign — a coated tongue or leukoplakia does not wipe away like that. There may also be soreness, altered taste and cracking at the corners of the mouth.
What is the best treatment for oral thrush?
Miconazole oral gel applied to the affected areas four times daily after meals is first-line for most adults, continued for about a week after symptoms clear. Nystatin suspension is an alternative, including for people taking warfarin. Oral fluconazole is used for extensive infection, symptoms reaching the throat, or where topical treatment has not worked.
How long does oral thrush take to clear?
Most cases improve within a few days and clear within one to two weeks of correct treatment. Treatment should continue for a short period after the patches disappear — about a week for miconazole gel and 48 hours for nystatin — because stopping the moment symptoms go allows regrowth. See a GP if there is no improvement after a week.
Can I use Daktarin gel if I take warfarin?
Not without advice. Miconazole interacts significantly with warfarin and can raise the risk of bleeding, so it should not simply be bought over the counter by anyone taking it. Nystatin suspension is the usual alternative in that situation. Miconazole also interacts with some statins, so tell the pharmacist everything you take.
Why do I keep getting oral thrush?
The common explanations are an inhaled steroid without mouth rinsing, dentures worn overnight or poorly fitting, a dry mouth from medicines or dehydration, repeated antibiotics, smoking, and raised blood glucose including undiagnosed diabetes. Repeated episodes in an otherwise healthy adult with none of those factors deserve investigation, including consideration of immune causes.
Is oral thrush contagious?
Oral thrush in adults is not contagious in ordinary social contact. The exception worth knowing about is between a breastfeeding mother and baby, where the infection can pass back and forth between the baby's mouth and the nipple, so both need treating at the same time.
References
- NHS. Thrush in men and women. nhs.uk
- NHS. Fluconazole: how and when to take it. nhs.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Candida — female genital. cks.nice.org.uk
- British Association for Sexual Health and HIV. Guidelines on the management of vulvovaginal candidiasis. bashh.org
- NHS. Bacterial vaginosis. nhs.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Vaginal and genital symptoms have several possible causes and thrush is only one of them. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.