Many popular herbal preparations have potential for serious toxicity. Nutmeg can cause hallucinations, agitation, gastrointestinal upset, miosis, coma, and hypertension. Ephedra, used for weight loss, contains ephedrine and can produce sympathomimetic toxicity, leading to strokes, seizures, and cardiac ischemia and dysrhythmias. Yohimbine is an α2-adrenergic receptor antagonist that may produce hallucinations, weakness, hypertension, and paralysis. Pennyroyal oil can cause hepatotoxicity. Absinthe (wormwood) contains volatile oils that can cause psychosis, intellectual deterioration, ataxia, headache, and vomiting. Black (or blue) cohosh, used to treat menopause, can induce nausea, vomiting, dizziness, and weakness. Juniper, used as a diuretic, can cause renal toxicity, nausea, and vomiting. Lobelia, used for asthma, can produce anticholinergic syndrome. Garlic, ginkgo, and ginseng have antithrombotic activity, which may precipitate bleeding in patients on warfarin. St John wort, in conjunction with other antidepressants, may precipitate serotonin toxicity.