The present invention is directed to racemic 1-(3,4-dichlorophenyl)-3-azab- icyclo[3.1.0]hexane, (+)-1-(3,4-dichlorophenyl)-3-azabicyclo[3.1.0]hexane, racemic 1-(4-methylphenyl)-3-azabicyclo[3.1.0]hexane, and (+)-1-(4-methylphenyl)-3-azabicyclo[3.1.0]hexane, and methods of their use for treating certain nervous system disorders and conditions, including, inter alia, vasomotor symptoms (VMS) and chronic pain.