Interactions with drugs can contribute to adverse effects, such as an increased risk of toxicities and ineffective therapy.
During cold and influenza season, many consumers elect to use various nutritional supplements marketed for immune health and support. Immune-boosting supplements may contain 1 or more of vitamins A, C, D, and E, along with trace elements of selenium and zinc. Some also contain echinacea, ginger, and other herbal ingredients for immune enhancement.
Other products marketed for immune support include prebiotics and probiotics. Some contain colostrum, which is rich in antibodies and immunoglobulins A and E that may provide immune-modulating benefits, while others may contain elderberry.1
In some cases, drug-supplement interactions can be of clinical importance but often go unrecognized by many consumers and health care professionals, according to the Handbook of Drug—Nutrient Interactions.2 As a result, a drug-supplement interaction may be a contributing factor in adverse drug effects, an increased risk of toxicities, or ineffective therapy.2 This is particularly critical in certain patient populations (see table 1).2,3
Augmenting awareness about drug-supplement interactions is critical to patient safety, ensuring optimal therapeutic effects, and preventing potential interactions. The results of some studies show that about 70% of patients taking prescription drugs do not inform their primary health care providers about their concurrent use of nutritional supplements.4 During counseling, pharmacists should encourage patients to maintain a comprehensive list of all medications, including supplements, and to adhere to manufacturer instructions and only take the recommended dosages. Pharmacists also can be instrumental in assisting patients in the proper selection of nutritional supplements and be a resource in identifying possible drug-nutrient contraindications and interactions (see table 2).5-12 Patients taking other medications and those with chronic medical conditions should always consult their primary health care providers before taking any supplements. When aiding patients seeking guidance about immune health supplements, pharmacists should also remind patients about the importance of obtaining their annual influenza vaccine during this time of year.
Yvette C. Terrie, BSPharm, RPh, is a consulting pharmacist and a medical writer in Haymarket, Virginia.