Painful oral ulcers with hydroxyurea therapy.

Five patients treated with hydroxyurea for various haematological malignancies developed multiple painful oral ulcers. Their neutrophil counts were either normal or elevated. The ulcers disappeared with cessation of hydroxyurea. Oral ulcers recurred when hydroxyurea was resumed in one of the patients. As the patients were unable to tolerate this painful side effect, hydroxyurea had to be discontinued. Appearance of painful oral ulceration seems to be independent of dosing rate or total cumulative dose of hydroxyurea.