Hydrocortisone and betamethasone are examples of low- and high-potency topical corticosteroids. Topical corticosteroids have been ranked in terms of potency into four groups consisting of seven classes. Class I topical corticosteroids are the most potent and Class VII are the least potent. Efficacy and side-effects are greatest with the Class I ultra-high-potency preparations which should only be used for limited time periods (2-3 weeks). Representative preparations by group are listed in the table below. These groups may vary depending on the formulation and concentration and should be considered approximate. In general, ointments are more potent than creams or lotions. Potency is also increased when topical corticosteroids are used under occlusive dressings or in intertriginous areas.