Thrush is an infection caused by yeasts (a type of fungus) called ‘candida’. Thrush can occur on the moist areas of the skin, vagina or in the mouth. Another common but different, fungal infection of the skin is tinea (ringworm) – see Tinea Health Information Brochure. Symptoms of thrush on the skin are a red itchy rash, with skin that is cracked with small sores or blisters.