Clinical diagnosis of skin and fungal nail infections are not always straightforward or easy. Inappropriate antifungal therapy has a significant cost implication for the NHS. Fungi of dermatological importance can be divided into yeasts (such as Candida and Pityrosporum) and dermatophytes (such as the fungi which causes ringworm and athlete's foot). Because some agents, such as imidazoles (e.g. miconazole, clotrimazole), will kill either of these two types of fungi, there is a clinical tendency for all anti-fungal therapies to be lumped together and viewed as equal. This is not correct. Anti-fungal treatments differ in their action against various types of fungi in a similar manner to the way antibiotics have different abilities to kill a variety of bacteria (broad or narrow spectrum antibiotics). Some medicines, notably terbinafine, also differ in the way they act depending on whether terbinafine is used orally or topically especially in the case of fungal nail infection.