Alcohol

Antidepressants (e.g., selective serotonin reuptake inhibitors, bupropion [Wellbutrin])

Beta blockers

Caffeine

Chemotherapy agents (selected)

Cimetidine (Tagamet)

Diuretics

Herbal remedies (selected)

Illicit drugs (selected)

Nicotine

Phenytoin (Dilantin)

Pseudoephedrine (Sudafed)

Steroids

Stimulant laxatives

Theophylline