A hitherto unknown risk of herbal medicine usage

Cardiovascular (and most other types of) patients frequently use herbal remedies in addition to their prescribed medicines. Can this behaviour create problems? Many experts think so.

The aim of a new study was to investigate the effect of herbal medicine use on medication adherence of cardiology patients. All patients admitted to the outpatient cardiology clinics, who had been prescribed at least one cardiovascular drug before, were asked to complete a questionnaire. Participants were asked if they have used any herbals during the past 12 months with an expectation of beneficial effect on health. Medication adherence was measured by using the Morisky Scale. High adherence was defined as a Morisky score lower than 2 and a score of 2 or more was seen as low adherence.

A total of 390 patients participated in this study; 29.7% of them had consumed herbals in the past 12 months. The median Morisky score was significantly higher in herbal users than non-users. The number of herbals used was moderately correlated with the Morisky score. In stepwise, multivariate logistic regression analysis, herbal use was significantly associated with low medication adherence.

From these findings, the authors conclude that herbal use was found to be independently associated with low medication adherence in our study population.

So far, the main known risk of herbal medicine use was the possibility that there might be herb-drug interactions. To the best of my knowledge, nobody has yet studied the possibility that herbal medicine users might neglect to take their prescribed drugs. The results of this investigation are somewhat worrying but they do make sense. Some patients who buy and take herbal remedies might think that they do not need to regularly take their prescribed medications because they already take herbal medicine which takes care of their health problem. They might even have been told by their herbalist that the herbal remedies suffice.

If that is so, and if the phenomenon can be confirmed in further investigations, it should be relevant not just in cardiology but in all fields of medicine. And if that is true for herbal remedies, it might also be the case for other types of alternative medicine. In other words, alternative medicine use might be a marker for poor adherence to prescribed medication. I feel that this hypothesis merits further study.

It goes without saying that poor adherence to prescribed drugs can be a very dangerous habit. Clinicians should therefore warn their patients and tell them that herbal remedies are no replacement of prescription drugs.