Hydroxyamphetamine is a derivative of amphetamines. Hydroxyamphetamine is intended mainly as local eye drops for diagnostic purposes. It is indirect sympathomimetic agent which cause dilation of the eye pupil before diagnostic test. Among the minor side effects from its use are: change in color vision, difficulty seeing at night, dry mouth, headache, increased sensitivity of eyes to sunlight, muscle stiffness or tightness and temporary stinging in the eyes. The main use of hydroxyamphetamines as eye drops is the diagnosis of Horner's syndrome which is characterized by nerve lesions. Hydroxyamphetamine hydrobromide is a component of FDA approved brand drug - Paremyd sterile ophthalmic solution (Hydroxyamphetamine hydrobromide, USP 1.0%, Tropicamide, USP 0.25%). Hydroxyamphetamine is an indirect-acting sympathomimetic, while tropicamide acts as a parasympatholytic.