Class 2c (AHP, 1997). Some thiol-bearing compounds in garlic and onion and their relatives can cause acantholysis in vitro (Brenner et al., 1995) and possibly pemphigus in vivo. "More than 5 cloves a day may induce flatulence and heartburn (Castleman, 1996) and 'thin blood'" (people taking blood thinners may overthin their blood thereby). Some people are very allergic to garlic. Contraindicated in hyperthyroid (TRA); Commission E reports rare GI disturbances, allergic reactions, and change of odor of skin and breath (Commission E). Allergic reactions of contact dermatosis and severe asthmatic attacks (from inhalation of garlic powder) may occur. Topical application of garlic or garlic oil may cause local irritating effects. Nausea, vomiting, and diarrhea may occur following ingestion of fresh garlic bulbs, extracts, or oil (AEH1). Sulfides may irritate the GI tract or cause dermatosis (CAN). Fresh garlic is reportedly dangerous to children (AHP). Use sparingly with children under 2 years of age; may irritate mouth or stomach if used too liberally (WAM). Then there is Miller and Murray's extremely cautious but not critical review (MAM). Although possibly "useful for mild hypertension ... routine use is not recommended (MAM)" After informing us that no drug-drug interactions have been reported for garlic, they feed us a long list of potential drug-drug interactions. Hasty readers, especially medical doctors, will take this as a proven drug-garlic interaction, "Avoid concomitant use ... with NSAIDS, anticoagulants and drugs that inhibit liver metabolism" (e.g., cimetidine (Tagamet), ciproflaxin (Cipro), clarithromycin, diltiazem (Cardizem), enoxacin, erythromycin, fluoxetine (Prozac), fluvoxamine, itraconazole, ketoconazole, nefazodone, paroxetine (Paxil), ritonavir) "may at least additively and perhaps synergistically interact with garlic." Watch also drugs extensively metabolized by the liver (alprazolam, amitriptyline, astemizole, carbamazepine, cisapride, clozapine, corticosteroids, cyclosporine, desipramine, diazepan (Valium), imipramine, phe-nytoin (Dilantin), propranolol, terfenadine (Seldane), theophylline, triazolam, warfarin (Coumadin), and drugs that may be affected by liver inhibition (e.g., propranolol, diazepam) (MAM). Miller and Murray (1998) tabulate allergic contact dermatosis, burning GI sensations, diaphoresis, diarrhea, light-headedness, menorrhagia, metrorrhagia, nausea, spinal epidural hematoma, and vomiting as side effects of garlic. They even try to attribute a case of spinal hematoma to garlic (in an 87-year-old male ingesting 2 g daily "to prevent heart disease." Perhaps they are too eager to accentuate the negative, attributing the problem "to garlic's ability to inhibit normal platelet function." Still accentuating the negative, they talk about rats given massive doses (50 mg/day garlic powder) developing degenerative changes in 45 days and severe testicular lesions after 70 days (MAM). The credibility of their uncritical data is questionable; for example, on one page (i.e., p. 144), they talk about 0.75 mg garlic essential oil divided in three doses a day causing anorexia, nausea, severe vomiting, diarrhea, marked weight loss, metrorrhagia, and menorrhagia; yet on the following page (i.e., p. 145), they casually discuss a dosage more than three orders of magnitude higher for 20 days lowering platelet aggregation from 30.37% to 21.21% (MAM). I feel I have to report this to my readers, although I consider it mostly hyperbolic. At 3 x 300 mg/day coated garlic powder tablet dosages, GI discomfort was the most frequent side effect (also bloating, dizziness, headache, hypotensive circulatory reactions, outbreaks of sweating); daily doses of 900 to 1200 mg were associated with garlic odor. "May potentiate the effect of antihypertensive and anticoagulant medications" (SHT). No known contraindications during pregnancy and lactation (SKY).
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