The use and abuse of cocaine is increasingly frequent in many countries, and the associated problems are increasingly evident. The effects of cocaine in the oral cavity vary depending on the form used and the route of self-administration. In the present study we describe the lesions observed in four patients with a history of topical self-application of cocaine to the oral and/or nasal mucosa, with the aim of relieving pain produced by cocaine-induced cluster headache. In three of the four patients this practice has led to erythematous lesions, while the remaining patient showed gingival recession and bone sequestration. These lesions can probably be attributed to the vasoconstrictor activity of cocaine, and to its caustic effects on the mucosa.