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.
Table 116-1 Symptoms of Hypervitaminosis ||Download (.pdf)
Table 116-1 Symptoms of Hypervitaminosis
|Vitamin A||Chronic toxicity: blurred vision, appetite loss, abnormal skin pigmentation, hair loss, dry skin, pruritus, long-bone pain, bone fractures, rare cases of pseudotumor cerebri, and hepatic failure|
|Vitamin D||Subacute toxicity: hypercalcemia, anorexia, nausea, abdominal pain, lethargy, weight loss, polyuria, constipation, confusion, and coma|
|Vitamin E||Chronic toxicity: nausea, fatigue, headache, weakness, and blurred vision|
|Vitamin B1 (thiamine)||No toxicity observed, even with ingestion of large doses over prolonged periods|
|Vitamin B2 (riboflavin)||No toxicity observed, regardless of amount ingested|
|Vitamin B3 (niacin)||Acute toxicity: niacin flush, dose >100 milligrams, redness, burning, and itching of the face, neck, and chest, rarely hypotension|
|Chronic toxicity: doses >2000 milligrams/d, abnormalities of liver function, impaired glucose tolerance, hyperuricemia, skin dryness, and discoloration|
|Vitamin B6 (pyridoxine)||Subacute and chronic toxicity: doses >5 grams/d or more over several weeks, peripheral neuropathy with unstable gait, numbness of the feet, similar symptoms in the hands and arms, marked loss of position and vibration senses|
|Vitamin B12||No toxicity observed, even with ingestion of large doses|
|Folate||No toxicity observed, even with ingestion of large doses|
|Vitamin C (ascorbate)||Chronic toxicity: attacks of gout, nephrolithiasis, intrarenal deposition of oxalate crystals with renal failure, large doses can produce diarrhea and abdominal cramps|
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 ...