Clotrimazole (Canesten): thrush, athlete's foot and ringworm

Clotrimazole is an antifungal, with Canesten as the best-known brand. The NHS lists vaginal thrush, penile and skin thrush, athlete's foot, ringworm, nappy rash, ear infections and intertrigo, the rash that forms in skin folds.

Its range of formats is wide: a skin cream in 1% or 2% strengths, a 10% vaginal cream, pessaries in three strengths, a 1% solution with a dropper and a 1% spray. Which one you need depends on where the fungus is.

Apply a thin layer of cream to the affected area and rub it in gently, 2 to 3 times a day for 2 to 4 weeks. The solution is applied with the plastic dropper in the same pattern. The spray is held about 15 cm away and used 2 to 3 times a day for up to 4 weeks. Keep spray away from naked flames.

Do not swallow clotrimazole. If you miss an application, put it on as soon as you remember.

The pessary strength sets the schedule. The NHS gives 100 mg as 1 pessary every night for 6 nights or 2 for 3 nights, 200 mg as 1 every night for 3 nights, and 500 mg as a single pessary for 1 night. The 10% vaginal cream is a single dose inserted at bedtime.

Do not use these products during a period, and avoid vaginal sex during treatment. Condoms and diaphragms may be damaged and are less reliable for at least 5 days after you finish.

The NHS says over-the-counter thrush treatment is not suitable if you are under 15 or over 60, have had thrush more than twice in 6 months, have or have had a sexually transmitted infection, have unusual discharge, sores, ulcers or abnormal bleeding, or if a partner has symptoms that are not the same as yours.

In those situations a pharmacist or doctor should assess you first. Tell them about earlier allergic reactions too.

The list exists because discharge and soreness can come from causes other than thrush, including infections that need a different test or treatment. Using an antifungal on the wrong problem can delay the right one, so when the picture is unclear the sensible default is to have it examined.

On the skin, expect occasional redness, itching, irritation, burning or stinging. Vaginal products may cause pain, swelling, discharge, bleeding or lower abdominal pain. A serious allergic reaction is possible but rare; call 999 if you suspect it.

An overdose is unlikely to cause problems, but seek advice if symptoms appear.

Clotrimazole is generally safe in pregnancy, but check with a pharmacist or doctor first. If you are using cream or solution on the breasts, wash it off with warm water before feeding.

The NHS names tacrolimus and Solfradex ear drops as products to check. You can eat and drink normally. Suspected side effects can be reported through the Yellow Card scheme.