Thrush is the common name for a condition known medically as oral candidosis or pseudomembranous candidosis. It is a fungal infection due to a type of yeast called candid
About 4 out of 10 of us have candida in our mouths and usually it causes no problems at all as it is kept in check by our body's natural defences, the immune system. Sometimes, however, the balance between the candida and our immunity can change so that the fungus grows and causes a troublesome infection.
Things that can lead to candida infections in the mouth include:
- chemotherapy: which can lower resistance and immunity.
- radiotherapy: which may cause some reduction in immunity or, if it is given to the mouth or nearby tissues may directly inflame the oral cavity leading to infection.
- general ill health where resistance is reduced
- diabetes
Thrush infections in the mouth can lead to soreness of the lining of the mouth, dryness of the mouth and an unpleasant metallic taste. Looking in the mouth the infection usually shows up quite obviously as creamy-white, curd like, plaques, surrounded by a thin red rim of inflamed tissue, on the lining of the mouth, throat and tongue. They may range in size from a pinpoint to several millimetres across and there may be just a few spots or virtually the whole mouth may be covered, depending on the severity of the infection.
Usually the diagnosis is quite obvious but sometimes doctors will take a swab of the lining of the mouth and send this for testing in the laboratory, just to be sure.
Usually thrush infections are not serious and can be very easily treated. The treatment generally involves medicines which act directly on the lining of the mouth and throat to kill off the fungus. These include amphotericin (which is usually prescribed as lozenges to be sucked four times a day), nystatin (which is often given as a mouthwash, which is rinsed round the mouth and then swallowed, so that it also reaches the throat, four times a day) or miconazole (which comes as a gel or a cream to be applied to the lining of the mouth).
These are usually given along with advice about oral hygiene, in particular the care and cleaning of any dentures and sometimes the suggestion of using a soft toothbrush to brush away the surface of the plaques of thrush.
Sometimes for more serious infections, or for people whose immunity is very low, other drugs may be given, as tablets or injections, which go into the blood stream and reach the infected tissues in this way, rather than attacking them from the surface. These drugs include fluconazole, itraconazole and ketoconazole. Amphotericin B is also given intravenously. In the past it often caused kidney problems but nowadays it is usually given in a fatty solution called liposomes, which reduces the side effects.
Candida fungal infections also occur quite commonly in otherwise completely healthy women affecting the lining of the vagina and the surface of the vulva. These infections are sometimes called 'vaginal thrush' and 'vulval thrush' and are usually easily treated by local antifungal creams or pessaries.