Chapter 116. Herbals and Vitamins

Over-the-counter herbal and vitamin preparations are widely used and considered innocuous by most of the public. Many of these herbal and vitamin products, however, can produce significant toxicity, especially if used in excess.

Common symptoms of vitamin toxicities are listed in Table 116-1.

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.

Diagnosis is usually made clinically. A history of massive acute ingestion or chronic supratherapeutic use should be sought. Laboratory studies that may be helpful include a basic metabolic panel, hepatic enzymes, coagulation studies, bleeding time, toxicology screen, and urine pregnancy test. An ECG may be indicated with signs of sympathomimetic stimulation.

Basic supportive care and discontinuation of the vitamin or herbal preparation is usually all that is needed if a patient presents with mild toxicity.

1. Consider activated charcoal 1 gram/kilogram PO for large vitamin A or vitamin D overdoses.

2. Treat hypercalcemia from vitamin A or D overdose with normal saline, furosemide, and prednisone (to reduce GI absorption).

3. Consider diagnostic and therapeutic lumbar puncture to treat increased intracranial pressure of pseudotumor from hypervitaminosis A.

4. Administer diphenhydramine 25 to 50 milligrams IV (1 milligram/kilogram in children) or PO to patients with “niacin flush” symptoms.

5. Consider N-acetylcysteine 140 milligrams/kilogram PO or IV for treating severe hepatotoxicity from herbal preparations such as pennyroyal oil.