Clotrimazole topical preparations are used to treat fungus infections on the skin. This medicine is available both over-the-counter (OTC) Although clotrimazole is available on prescription, you can also buy some preparations without a prescription at pharmacies and other retail outlets. It is available as a cream, as a spray and as a topical solution (a liquid which is applied directly on to the skin)h your doctor's prescription. This product is available in the following dosage forms: Cream. Clotrimazole works by killing the yeast that causes the fungal infection. It usually treats thrush within 7 days but it's best to treat the infection for at least 2 weeks to stop it coming back. The most common side effect is an itching or burning feeling in the area being treated.