Introduction

St John's wort (Hypericum perforatum) is a common herb that has been used medicinally since the times of Hippocrates and Galen, who used it as a cure for intestinal worms. The active compound is hypericin and the herb is commonly taken for depression. It is commonly believed that herbal remedies are ‘safer’ than synthetic medicines, but we should not assume that the herb is harmless. Two cases of organ rejection have been attributed to a reduction of plasma ciclosporin levels, possibly owing to an effect of St John's wort on cytochrome p450 in the liver (Reference Ruschitzka, Meier and TurinaRuschitzka et al, 2000), and a recent warning by the chief medical officer advised against taking St John's wort with a number of drugs, including theophylline, digoxin, warfarin, ciclosporin, indinavir and the oral contraceptive pill (Department of Health, 2000). The same report also suggested that it is inadvisable for patients to take St John's wort with selective serotonin reuptake inhibitor (SSRI) anti-depressants, as the herb may increase serotonin levels. Other side-effects and drug interactions have also been described (Reference ErnstErnst, 1999). We carried out a survey to measure the proportion of new mental health referrals who were self-medicating with St John's wort.

Methods

The study was conducted by an inner-London general adult community mental health team. All new referrals over a 5-month period were included. The interview took place during the initial assessment and was always performed by a doctor. We asked the patients if they had ever taken St John's wort and if they had taken it in the past 3 months, the dose they had taken, and any other comments. The age and gender of the patients were recorded along with the clinical diagnosis made by the assessing doctor.

Results

A total of 114 patients were seen and data were obtained for 101 (89%). We found that 15 had taken St John's wort at some time for psychiatric symptoms. These patients were younger (mean age 31.6 v. 42.7 for the whole group, independent T test P=0.01) and included more female patients (73% compared with 57%, χ² test not significant). Eleven had taken the herb in the past 3 months and seven were taking it at the time of presentation. Of the 15 patients that had used St John's wort, nine had depressive symptoms either in isolation or together with anxiety disorders or dysthymia. Six patients self-medicating did not have depressive symptoms.

Most (12) patients had heard of it through family/friends, one via the media and one from a healthfood shop. None had sought professional advice beforehand and only six were aware of the dose they had taken. One patient suffered a photosensitivity reaction after taking St John's wort for 2 weeks, which resolved when discontinued, a side-effect previously reported (Reference BoveBove, 1998). Of the seven patients taking St John's wort, one was taking an interacting medication.

Discussion

A significant number of patients self-medicate with St John's wort before they present to the psychiatric services. Although St John's wort has been used for over 2400 years and is considered to have relatively few side-effects, its clinical profile is changing through interactions with modern medicines.

The two important implications of this survey are the need to educate clinicians and patients. Clinicians need to be aware when prescribing that many patients will already be taking St John's wort. Clinical trials have established the use of hypericum as an antidepressant only and it is as effective as conventional antidepressants in treating mild to moderate depression (Reference Linde, Ramirez and MulrowLinde et al, 1996). It is a psychotropic drug but we do not routinely ask about its use. It is important we do so because it has interactions with medical drugs and SSRI antidepressants that psychiatrists may wish to prescribe.

This study highlights the need to improve patient education about which illnesses benefit most from hypericum and in what doses. Patients tended not to discuss starting on St John's wort with their doctor, a finding also found in the US (Reference Wagner, Jester and LeclairWagner et al, 1999). The public need to be aware of potential side-effects and drug interactions, as they can perceive St John's wort to be safer than conventional prescription drugs (Reference Wagner, Jester and LeclairWagner et al, 1999). This survey suggested younger women are more likely to use St John's wort. The risk of pregnancy when using the oral contraceptive may not be known by the user.

While these problems might suggest that St John's wort should be prescribed by physicians, it should be noted that some foods also potentiate sub-enzymes of the P450 system, such as cabbage and sprouts (Reference Jobst, McIntyre and St GEORGEJobst et al, 2000). St John's wort may be a useful addition to therapeutic options and if the public are educated about its uses and risks then self-medication may be a useful and acceptable choice. However, the risk of drug interactions and side-effects suggests a need either to regulate its use or provide clear information and warnings when purchasing St John's wort.

Declaration of interest

R.L. has been principal investigator in a trial sponsored by Lilly Pharmaceuticals.