Iron
Chloroquine, quinine, quinidine and hydroxychloroquine (plaquenil)
Clonidine (Catapres)
Sulfonylureas (Glyburide, Tolbutamide, brand names: Micronase, Diabinese, Orinase and Glucotrol)
Tricyclic antidepressants (Tofranil, Desipramine and Amytriptyline brand names: Pamelor and Elavil)
Lindane (Kwell)
Diphenoxylate/atropine (Lomotil)
Beta blockers (propranolol, carvedilol, atenolol, labetalol, nadolol, metoprolol brand names: Inderal, Coreg, Tenormin, Normodyne, Trandate, Corgard and Lopressor).
Theophylline
Calcium channel blockers. (verapamil, diltiazem, nifedipine, nicardipine, felodipine, isradipine, amlodipine, nisoldipine and bepridil. brand names: Procardia, Veralin, Calan, Isoptin, Cardizem, Plendil, Dilacor, Sular, Norvasc, Dynacirc, Adalat and Vascor)
Camphor (camphorated oil, Ben-Gay Children's Rub and Vicks VapoRub)
Methyl Salicylate (oil of wintergreen, Ben-Gay)
Oxymetolazine (Visine, Afrin) - alpha 2 agonist
Benzocaine (Orajel, Anbesol, Vagisil) - methemoglobinemia