Natural products and supplements are no different to medicine, as they can potentially have a beneficial effect on our health but then they can also potentially have a negative effect. They can interact both with other natural products or with pharmaceutical medicines.
The team at Health House are often asked about interactions with medicines and they wisely advise that you need to check with your doctor or pharmacist. However, here is a list of 13 natural products for which interactions are common and/or potentially serious:
Black Cohosh - can cause liver toxicity and may interact with other medicines which can impact the liver, such as atorvastatin and paracetamol. Prescription drugs broken down by certain liver enzymes may accumulate in the body and lead to toxicity, if used with black cohosh.
Coenzyme Q10 - when used with anticoagulant drugs such as warfarin may interact with blood thinning effects.
Cranberry - this can exert an increased effect on anticoagulants and lead to bruising or bleeding. Patients taking warfarin may need to have their International Normalised Ratio (INR) or other blood clotting lab test checked more frequently.
Echinacea – as it can stimulate the immune system it can also antagonize the effects of medications which act by lowering immune system activity, such as azathioprine, cyclosporine, tacrolimus and corticosteroids.
Valerian - this potent natural sedative can potentially interact with muscle relaxants, sleep or anxiety medicines, pain medicines, antidepressants, or other medicines that cause drowsiness.
St. John's Wort - has many drug interactions, some of which can be dangerous. It can interact with selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAO inhibitors), dextromethorphan, warfarin, oral contraceptives, certain HIV medications, digoxin, statins and many other drugs.
Saw Palmetto - used for prostate gland enlargement, it should usually be avoided if taking other agents used to treat this condition, such as finasteride. It can also slow blood clotting and increase the risk of bruising or bleeding if used with anticoagulants.
Melatonin - this natural hormone helps to regulate the sleep-wake cycle and can cause drowsiness. Therefore users should avoid alcohol and other sedating medicines (for example, benzodiazepines sedatives and hypnotics, some antihistamines, opioid analgesics).
Kava - has hundreds of drug interactions. In particular, it should not be used with medicines which can cause liver toxicity. The use of buprenorphine with kava can lead to serious side effects such as respiratory distress or coma.
Ginseng - the most important interaction to be aware of is that long-term use of ginseng can decrease the effect of warfarin.
Feverfew - increases the risk of bleeding, especially in people with blood-clotting disorders or using blood thinners such as aspirin, warfarin, heparin or clopidogrel.
Ginkgo Biloba - can also alter the actions of medicines metabolised through the liver; the list is extensive and around 500 medicines are known to interact with this herbal product.
Garlic - reduces blood clotting and therefore can increase the effects of blood thinning medicines.