A letter to the British Medical Journal warns that natural remedies can be harmful.

Certainly a few

treatments such as kava (Piper methysticum), which is rich in coumarins which interfere with warfarin, have been mentioned in the BMJ

in the past year.

In our practice we have seen a case of severe dyspepsia caused by zinc, which had been bought by mail after hair analysis by mail, being

taken at six times the recommended daily allowance; a patient with blood pressure that was difficult to control because of ginseng; a

patient with severe headaches on waking caused by evening primrose oil; and a patient with myopathy caused by creatine, to mention

only a few. These conditions necessitated an endoscopy, a medical referral, and a computed axial tomography scan, as well as numerous

blood tests. The aetiology was only ascertained by direct questioning. All cases resolved when the patients stopped taking the substance.

We suspect that these cases represent the tip of the iceberg.

Caution should be exercised in condoning the use of any supplement or herbal preparation without checking with a pharmacist or reliable

source. Many herbal remedies are dangerous to patients with epilepsy or diabetes and to those taking warfarin; they also have the

propensity to cause illness in those who are otherwise healthy and not taking drugs.

By coincidence, just today, I discovered that the troubling cognitive dysfunction I’ve seen in a hospitalized patient of mine is probably attributable not to her psychiatric condition, nor her serious medical conditions, but to poisoning with dietary supplements she had been taking unbeknownst to her doctors.