Herbal remedies should always be considered when reviewing patients' medication, although research on drug interactions with herbal remedies has been sparse. St John's wort is a herbal remedy that has been around for hundreds of years to treat mental health problems, and is bought over the counter in the UK for mild-to-moderate depression, as well as for seasonal affective disorder (SAD), mild anxiety and sleep problems (Mind, 2020). Although it is not a ‘drug’ regulated and approved by the Medicines and Healthcare products Regulatory Agency (MHRA), it is popular for its perceived antidepressant effects, and knowledge of it and its interactions with other medications is important.
St John's wort (Hypericum perforatum) contains many active substances, such as hypericin and hyperforin, which are thought to have an effect on mood. These substances are believed to work in the same way as standard antidepressant medications, increasing the activity of serotonin and noradrenaline to help regulate mood (Mind, 2020). St John's wort should not be used to self-medicate if patients are experiencing struggles with mental health without talking to a doctor first, as this may be dangerous, and it may not be the right drug for the patient. It may also interact with a medication the patient is already taking (for example, the combined pill) and may have an adverse effect if the person is bipolar (Mind, 2020), causing hypomania.
St John's wort is a herbal remedy that has been used for hundreds of years to treat mental health problems, including depression, and it is bought over the counter in the UK
Barnes et al (2021) noted that, although the chemical composition of St John's wort has been well studied, the constituents of the substance that actually induce the antidepressant effect are unknown (apart from hypericum, and particularly hyperforin, which is known to have this effect). Hypericin is also thought to be responsible for reported photosensitive reactions, and antiviral and antibacterial effects have also been documented (Barnes et al, 2021).
Barnes et al (2021) reviewed randomised controlled trials to explore the efficacy of the extracts of St John's Wort over placebo, in the treatment of mild-to-moderate depression (it has already been noted to be ineffective for severe depression (Mind, 2020)). There is some evidence that St John's wort extracts are as effective as some standard antidepressant medications for mild-to-moderate depression, but the researchers highlighted the need for further trials to assess its efficacy in comparison with that of standard antidepressants, especially in the case of the newer antidepressant drugs, such as selective serotonin reuptake inhibitors. They noted that research in well-defined groups of patients with different types of depression, conducted over longer periods, is needed to determine long-term safety.
However, in terms of its short-term safety profile St John's wort does appear to be superior to standard antidepressants (Barnes et al, 2021). The main concerns raised relate to interactions between St John's wort and certain prescribed medicines, such as warfarin, ciclosporin, theophylline, digoxin, HIV protease inhibitors, anticonvulsants, selective serotonin reuptake inhibitors, triptans and oral contraceptives (Barnes et al, 2021). Where it can be seen that a patient is taking any of these medications, Barnes et al (2021) recommended that the patient be advised to stop taking St John's wort. However, it is best practice to contact the patient's GP and explain the issue, as they may need a full medication and mental health review so that they do not abruptly stop taking something that is helping their mental health, as well as to ensure that they also receive the correct medications for their physical health.
The National Center for Complementary and Integrative Health (NCCIH) (2017) in the US emphasised how essential it is for patients to seek the right help for depression. For patients who may be self-medicating for depression without the knowledge of their GP, it would be important to seek a review as soon as possible, considering interactions with current medications, other lifestyle factors and advice they may need, as well as referrals to talking therapies, if required. Severe cases of depression may lead to an increased risk of suicide (NCCIH, 2017). Therefore, there should be no delay in seeking assistance from a healthcare provider for a mental health issue, and herbal remedies should not replace conventional care. Additionally, St John's wort may not be suitable for pregnant or breastfeeding women (NCCIH, 2017).
Overall, it appears that this popular herbal remedy has some benefits for those with mild depression, but, where there is concern regarding the potential for more severe depression, a discussion with both the patient and GP would be required to determine next steps. If the patient feels that St John's wort is effective for them and they do not take other medications which may interact, it may be decided that they simply continue with it. However, for many patients, there may be significant interactions with drugs that they already take, which would not only reduce their effectiveness, but also hamper health. A comprehensive review of patients' medication is always required, and the importance of considering herbal remedies as a piece of the puzzle should never be underestimated.