Prescription amphetamines have been used for short periods of time in weight-control programs to suppress appetite and to treat narcolepsy. They were used as vasoconstrictors in inhalant therapy to shrink nasal mucous membranes in such conditions as nasal allergies and asthma; now such inhalants have been banned because of their toxicity. For unknown reasons, amphetamines have a paradoxically calming effect on some hyperactive children, but the use of these drugs to treat such children has been controversial.