The need for caution when combining drugs and herbal supplements

Medication information

The staff at Vivian Pharmacy are passionate about Pharmaceutical Care. Our mission is to provide our patients with the best pharmaceutical service by ensuring they are well supported in taking their medications effectively and safely. We have a team of clinically orientated pharmacists and pharmacy technicians who are always happy, in addition to medication supply, to answer drug questions, counsel patients and provide medication education.

Here is the next article in our series on the complexities of safe and effective Pharmaceutical Care.

Words by Ger Jones, pharmacist

Herbal supplements are currently very popular and some have reasonable evidence to support their effectiveness. The availability of conventional medicine (allopathic) and herbal supplements can give patients and customers the best of both worlds but combining herbs and pharmaceutical drugs can, in some instances, be dangerous. Many popular herbal remedies can clash with prescription and non-prescription drugs, occasionally with severe consequences.

Let us choose one herb to illustrate the potential problem, the popular herb St. John’s wort (Hypericum perforatum). This herb, similarly to other herbs, contains a whole host of different chemical components that may contribute to its medical effects. St. John’s wort is sometimes considered by patients as an option for the short-term treatment of mild depression. Many people mistakenly believe St. John’s wort to be safe because it is “natural”. However natural does not always mean safe. Some of the strongest medications come from natural sources such as digoxin from the foxglove (D. purpurea) and morphine from the opium poppy (Papaver somniferum). Paracelsus was probably accurate in his statement “All substances are poisonous, there is none that is not a poison; the right dose differentiates a poison from a remedy”.

St. John’s wort appears to work by increasing one of the brain chemicals called serotonin (simplistically, the “happy chemical”).

Let us consider some examples of how St. John’s wort can interact with prescription medications.

• St. John’s wort may interact with medications used to treat depression or other mood disorders, including SSRIs, tricyclic antidepressants and monoamine oxidase inhibitors. Taking St. John’s wort along with these medications for depression might increase serotonin levels too much and cause serious side effects including heart problems, shivering, and anxiety. (a combination of symptoms referred to as Serotonin Syndrome).

• Warfarin is an extremely important medication and is used to slow blood clotting (thus preventing certain types of strokes and other clot related conditions). The body breaks down warfarin to get rid of it. St. John’s wort could increase the breakdown and decrease the effectiveness of warfarin, which may increase the risk of clotting.

• The important drug Tacrolimus, which is used to prevent organ rejection after transplants, interacts with St. John’s wort. St. John’s wort can increase how quickly the body breaks down tacrolimus. This can cause tacrolimus to be less effective.

Having a range of both conventional and complementary therapy options can be good for patient choice. Certainly, St. John’s wort may have a role in mild depression. However, if you are on any prescription medicines and are considering taking any herbal supplements please check with your pharmacist first to ensure there are no potential safety issues.



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