Oral thrush: symptoms, treatment and how long it lasts

The NHS says oral thrush can be treated with a mouth gel bought from a pharmacy. The gel is suitable for adults, children and babies over 4 months of age, and you should follow the instructions on the packet. A pharmacist can advise if you are not sure it is thrush or which product to use.

When treatment is prescribed, NICE Clinical Knowledge Summaries (CKS) sets out the usual order. In someone who is not significantly immunocompromised and has mild, localised infection, a topical antifungal is used. Miconazole oral gel is first choice for adults and for children aged 4 months and over. If it is unsuitable, nystatin suspension is offered.

Tablets are kept for harder cases. NICE CKS says that if topical treatment is ineffective, the infection is extensive or severe, or the person is significantly immunocompromised, oral fluconazole may be prescribed for people aged 16 and over, with review after the first course.

NICE CKS says people taking warfarin should be aware of an interaction with miconazole, and that miconazole should not be prescribed to people taking a statin, in which case nystatin is used. People taking a sulfonylurea such as gliclazide should be aware of interactions with miconazole or fluconazole.

Always tell the pharmacist or prescriber what else you take before starting a mouth gel, and read the leaflet. Do not stop a regular medicine because of thrush without asking the person who prescribed it.

The NHS says that when you have oral thrush your mouth is red inside with white patches. When you wipe off the patches they leave red spots that can bleed. Other symptoms in adults 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 sore gums, and difficulty eating and drinking.

NICE CKS describes the typical pseudomembranous form as curd-like white or yellowish plaques that can occur anywhere in the mouth, especially the cheeks, gums, palate and tongue. These are easily removed, revealing a red base that is not usually painful, and symptoms may be minimal, with a burning or itching feeling.

There are other presentations, listed below. Not every white patch in the mouth is thrush, which is why a patch that cannot be wiped away is worth having looked at.

The NHS says oral thrush in adults is not contagious. NICE CKS explains why: Candida is a yeast-like fungus that is part of the normal flora of the gut, and colonisation is usually without symptoms. Oral carriage is reported to be around 30 to 45% in healthy adults, and 45 to 65% in healthy children.

So thrush is not usually a case of catching an infection from someone else. It develops when the balance in your mouth is disturbed, for example by medicines or a weakened immune system.

The NHS says oral thrush is caused by a fungus called Candida and that some things make it grow more than usual. You may get thrush if you are taking antibiotics over a long time, using asthma inhalers or having cancer treatment such as chemotherapy.

NICE CKS adds that conditions that raise the risk include diabetes, severe anaemia and immunocompromise (for example chemotherapy, radiotherapy or HIV). Other risk factors it lists are poor dental hygiene, local trauma, smoking, broad-spectrum antibiotics, inhaled or oral corticosteroids, and malnutrition.

CKS also notes that oral candidiasis is uncommon in people other than infants, denture wearers and older people, and that in otherwise healthy people it may be the first sign of an undiagnosed risk factor such as diabetes or a low vitamin or iron level. That is why a GP may look for a cause when thrush is recurrent.

Oral thrush, also called oral candidiasis, is a yeast infection of the lining of the mouth. Most cases are caused by Candida albicans. Candida is normally present without causing problems, but if the mucosal barriers are disrupted or the body's defences are lowered it can cause infection.

The NHS describes it as usually harmless. NICE CKS says the diagnosis is usually made by recognising the clinical features and excluding other conditions, and that swabs are not usually diagnostically helpful because Candida is a normal commensal found in many healthy people.

The pages used for this guide do not describe home remedies as a treatment for oral thrush. What the NHS does describe is a set of habits that reduce the chance of it developing or returning. NICE CKS gives more detail for people who use inhalers or wear dentures.

• Brush your teeth twice a day, clean your dentures and keep going to regular dental check-ups, even if you have dentures.

• If you have no teeth, brush your gums and tongue with a soft toothbrush.

• Rinse your mouth after eating or taking medicine, and after inhaled steroid doses; NICE CKS also advises good inhaler technique and a spacer device.

• Do not wear dentures at night, and do not keep wearing dentures that do not fit properly; see your dentist. NICE CKS says dentures should be out for at least 6 hours in each 24 hours.

• Do not smoke; NICE CKS lists smoking as a risk factor.

• Go to regular check-ups if you have a long-term condition such as diabetes.

• For babies, sterilise dummies regularly and sterilise bottles after each use.

The sources do not give a single recovery time, because it depends on the treatment and the person. The NHS says to see a GP if there is no improvement after 1 week of treatment with a mouth gel. NICE CKS advises continuing miconazole for at least 7 days after the lesions have healed or the symptoms have cleared, so that the infection does not return straight away.

For adults who needed fluconazole for extensive infection, CKS says to review after 14 days and, if not fully resolved, to consider a further 7 days, swabbing, specialist advice or referral. For children, CKS advises seeking specialist advice if there is no adequate response after at least 2 weeks of treatment.

The NHS says oral thrush is common in babies. A baby with oral thrush has a white coating on the tongue that may look like cottage cheese and cannot be rubbed off easily. There are sometimes white spots in the mouth, and a baby may not want to feed.

See a GP if your baby is under 4 months and has signs of oral thrush. For children aged 4 months and over, NICE CKS recommends miconazole oral gel first-line, with nystatin suspension if miconazole is unsuitable. It advises seeking paediatric or specialist advice if a child has extensive or severe infection, does not respond to at least 2 weeks of treatment, has recurrent episodes, or if immunocompromise is suspected.

NICE CKS also says oral candidiasis is common in infants but in older children it may signify an immune problem or another illness, which is why risk factors are looked for.

The NHS lists three situations for a GP appointment: a baby under 4 months with signs of oral thrush, no improvement after 1 week of treatment with a mouth gel, and difficulty or pain when swallowing.

NICE CKS goes further for clinicians. It says admission should be arranged if there is widespread infection, such as oesophageal candidiasis (difficulty or pain on swallowing, or pain behind the breastbone), or if the person is systemically unwell. It also advises referral or specialist advice for recurrent episodes, breakthrough infection while on preventive treatment, or if there is doubt about the diagnosis, and consideration of biopsy for chronic plaque-like candidiasis that does not respond to treatment because of the risk of malignancy.

If you feel generally very unwell, or swallowing is painful or difficult, speak to a GP promptly rather than waiting for the gel to work.

Many people never need more than a pharmacist, because the NHS says a mouth gel can be bought over the counter. A GP or a dentist can also assess a sore or patchy mouth and prescribe treatment, and dentists are well placed to review dentures.

If thrush keeps returning or does not respond, NHS care may involve checking for diabetes or other risk factors and, in some cases, referral to a specialist in oral medicine or oral surgery. Some people choose to see a private dentist or specialist for the same reasons. In either setting the questions are similar: what is driving the infection, whether a medicine can be changed, and how to look after dentures or inhalers.