Tetracyclines (tetracycline, minocycline, doxycycline)

Sulfonamides, other sulfa drugs

Metronidazole, nystatin, salicylates, NSAIDs, phenylbutazone, phenacetin

Barbiturates, benzodiazepines

Oral contraceptives

Quinine (including quinine in tonic water), quinidine

Phenolphthalein

Food coloring (yellow): in food or medications