Differences in perceived risks and benefits of herbal, over-the-counter conventional, and prescribed conventional, medicines, and the implications of this for the safe and effective use of herbal products

Summary

Objectives

To investigate people's views about the efficacy and specific risks of herbal, over-the-counter (OTC) conventional, and prescribed conventional medicines, and their likelihood of taking a second (herbal or OTC conventional) product in addition to a prescribed medicine.

Methods

Experiment 1 (1 factor within-participant design); Experiment 2 (1 factor between-participant design). Convenience samples of general population were given a hypothetical scenario and required to make a number of judgements.

Results

People believed herbal remedies to be less effective, but less risky than OTC and prescribed conventional medicines. Herbal medicines were not seen as being safer simply because of their easier availability. Participants indicated that they would be more likely to take a herbal medicine than a conventional OTC medicine in addition to a prescribed medicine, and less likely to consult their doctor in advance.

Conclusion

People believe that herbal medicines are natural and relatively safe and can be used with less caution. People need to be given clear information about the risks and benefits of herbal medicines if they are to use such products safely and effectively.

Introduction

The sale and use of herbal medicines has increased significantly over the past 20 years. Eisenberg et al.,¹ for example, reported that use of herbal medicines in the US increased from 2.5% in 1990 to 12.1% in 1997, with a total of $ 5 billion being spent. Within the UK, Thomas et al.² found that over 30% of a random sample of 5010 adults were taking, or had been taking, herbal remedies. Despite this increase in usage, and the concurrent increase in the amount of information promoting usage, there are still relatively few studies that have examined people's beliefs about the risks and benefits of herbal products, particularly as a distinct medicine type (rather than asking about complementary medicines in general). Thus, the majority of studies in the area have compared experiences with, and views about, complementary as opposed to orthodox medicines.3, 4, 5, 6 Such general comparisons, however, make it more difficult to address a number of key questions.

For example, one reason for the increased usage of complementary, including herbal, medicines is that such products are believed to be safer than orthodox treatments,7, 8, 9, 10 but it is not clear from the existing studies what underlies this perception. Thus, are herbal medicines perceived to be safe because they are more readily available, or for some other reason, such as their being a more natural product? In relation to this, Tomassoni and Simone¹¹ proposed that the over the counter availability of herbal medicines fosters the notion that they are safe. The present study compares people's views about the risks and benefits of herbal, over-the-counter (OTC) conventional, and prescribed conventional medicines. This should provide a more thorough understanding of people's views of the relative safety of the three medicine types, as well as what might underlie any differences in perceptions.

There is also evidence that people do not inform their physicians if they are taking complementary medicines.7, 12, 13, 14 Eisenberg et al. found that of the 34% of respondents who reported using at least one complementary therapy in the past year, 72% did not inform their doctor. More recently, Bennett and Brown found that the majority of users (86%) did not discuss their use of herbal remedies with their doctor. The evidence on this is mixed, however. Klepser et al. reported that both users and non-users of herbal therapies indicated that they would disclose such information if asked by doctors and pharmacists (although the study did not assess whether such information would be volunteered spontaneously). In addition, Harnack et al.¹⁵ reported that 89% of their sample of 376 US respondents agreed with the statement “you should inform your physician of any herbal products you are taking”.

A related question concerns whether people would consult their doctor if they experience an adverse side effect as a result of taking a herbal product. It has been reported that many people do not associate adverse reactions with herbal products they are taking, as they believe the products are safe. As a result, many do not inform their doctors when they experience a reaction. Barnes et al.¹⁶ found that patients were less likely to report adverse reactions resulting from use of a herbal product compared with a prescription drug.

Experiment 1 in the present study specifically compares people's views about the risks (adverse side effects, dependency, interaction with prescribed medicines) and benefits of herbal, over-the-counter (OTC) conventional, and prescribed conventional medicines in order to gain a better understanding of people's views of the relative safety of the three medicine types, as well as what might underlie any differences in perceptions. Thus, herbal medicines may be seen to differ from OTC and prescribed (conventional) medicines because they are seen as being more natural. Alternatively, herbal and OTC medicines may differ from prescribed medicines because the former two are more easily available and can be self-prescribed. Experiment 2 looks at how likely it is that people would take a herbal or OTC product in addition to a prescribed medicine, whether they would seek advice in advance of doing this (and from what source), and what action they would take if they experienced an adverse effect.