White patches in the mouth: thrush, leukoplakia and other causes

A white patch can sit on the tongue, the inner cheeks, the gums, the roof or the floor of the mouth. Most of the time it has an ordinary explanation, such as a fungal infection, irritation from a rough tooth or denture, or a long-term inflammatory condition. The reason the NHS emphasises checking is that a small number of patches are precancerous or cancerous, and the appearance alone cannot distinguish them reliably.

The most helpful first observation is whether the patch wipes off. Beyond that, how long it has been there, whether it hurts, and what else is going on in the mouth help the dentist or GP narrow things down.

The NHS says that in adults with oral thrush the mouth is red inside with white patches, and that wiping the patches leaves red spots that can bleed. Other symptoms are cracks at the corners of the mouth, not tasting things properly, an unpleasant taste, pain inside the mouth such as a sore tongue or gums, and difficulty eating and drinking. In adults it is not contagious.

It is caused by a fungus called Candida. The NHS says some things make it grow more than usual: taking antibiotics over a long time, using asthma inhalers or having cancer treatment such as chemotherapy, and nidirect adds poorly fitting dentures, poor oral hygiene, diabetes, a dry mouth, smoking and a weakened immune system. A pharmacist can supply an antifungal mouth gel, and the NHS says to see a GP if there is no improvement after 1 week of treatment or if swallowing is difficult or painful.

The NHS lists white patches on the gums, tongue or insides of the cheeks among the symptoms of lichen planus, which can also cause burning and stinging in the mouth, especially when eating or drinking. Lichen planus in the mouth can last for several years, and mouthwashes and sprays from a GP can ease burning or sore gums. The NHS mouth ulcers page describes oral lichen planus as causing a white, lacy pattern inside the cheeks.

Leukoplakia is described by the NHS as a white patch or patches in the mouth that are not usually painful, are irregular in shape, may be slightly raised, may have red areas within them and cannot be rubbed or scraped away. They often appear on or below the tongue. Smoking and chewing tobacco are thought to increase the chance of getting it. If leukoplakia is suspected the patch is examined, other causes such as thrush or cheek biting are ruled out, and a specialist may take a biopsy. Treatment is not always needed, but regular check-ups are advised, and surgery is sometimes used if there is a chance of the patch becoming cancerous.

The table summarises features the NHS gives for the common causes of white mouth patches. It is a guide to the questions a clinician will ask, not a way to diagnose yourself, and the NHS itself says not to self-diagnose.

The NHS advises seeing a dentist or GP if you have a white patch in your mouth that does not go away. It also advises seeing them if you have a white patch on the tongue and a weakened immune system, such as from HIV or an organ transplant, or if you have pain or discomfort that is not going away.

The NHS mouth cancer symptoms page lists a mouth ulcer lasting more than 3 weeks, a red or white patch, a lump in the mouth or on the lip, pain, difficulty swallowing or speaking, a hoarse voice, a lump in the neck or throat and unexplained weight loss. It says you may get an urgent referral if the GP thinks your symptoms could be cancer, and that this does not definitely mean you have cancer.

The NHS suggests that people with leukoplakia can help patches to shrink or go away by stopping smoking, stopping or reducing alcohol and not chewing tobacco, paan or betel nuts. It also suggests regular dental check-ups, taking care of teeth and gums, making sure dentures fit properly and eating a balanced diet with plenty of fresh fruit and vegetables.

To prevent oral thrush the NHS advises brushing twice a day, cleaning dentures, not wearing dentures at night, going to regular check-ups, and rinsing the mouth after eating or taking medicine if you do not have teeth. It also says people with long-term conditions such as diabetes should keep to their check-ups.