what are the side effects of the drug venlafaxine?
['unusual dreams.', 'sexual problems, such as: decreased interest in sex. impotence (not being able to get or keep an erection) trouble having an orgasm.', 'loss of appetite.', 'constipation.', 'nausea or vomiting.', 'dry mouth.', 'tiredness.', 'trouble sleeping or change in sleep habits.']