The following information comes from DailyMed, an FDA label information provider.
In a controlled clinical trial with clobetasol propionate gel, the only reported adverse reaction that was considered to be drug related was a report of burning sensation (1.8% of treated patients). In controlled clinical trials, the most frequent adverse reactions reported for clobetasol propionate cream were burning and stinging sensation in 1% of treated patients. Less frequent adverse reactions were itching, skin atrophy, and cracking and fissuring of the skin. In controlled clinical trials, the most frequent adverse events reported for clobetasol propionate ointment were burning sensation, irritation, and itching in 0.5% of treated patients. Less frequent adverse reactions were stinging, cracking, erythema, folliculitis, numbness of fingers, skin atrophy, and telangiectasia.
Cushing’s syndrome has been reported in infants and adults as a result of prolonged use of topical clobetasol propionate formulations. The following additional local adverse reactions have been reported with topical corticosteroids, and they may occur more frequently with the use of occlusive dressings and higher potency corticosteroids. These reactions are listed in an approximately decreasing order of occurrence: dryness, acneiform eruptions, hypopigmentation, perioral dermatitis, allergic contact dermatitis, secondary infection, irritation, striae, and miliaria.
There may be other adverse effects not mention above depending upon duration and frequency of application some clobetasol does get absorbed.