More than 62 million cases of the common cold are reported annually in the United States.1 Rhinoviruses are the most prevalent causes; however, >200 viruses are known to cause colds. Cold symptoms usually appear 1 to 3 days after an individual is infected.
Although many patients attempt to treat themselves, there is still no known cure for the common cold. In recent years, great interest has arisen in the use of alternative products?such as echinacea, zinc, and vitamin C?for the prevention and/or treatment of the common cold2 (Table).
Echinacea purpura is used as an immunostimulant. It is available in various formulations as a single entity or in combination with other ingredients such as zinc. The results of a recent study were published on July 28, 2005, in the New England Journal of Medicine. Researchers found that echinacea had no clinical or significant effects in preventing colds or reducing either the length or severity of cold symptoms of the individuals in the study. Currently the National Center for Complementary and Alternative Medicine is supporting other studies to find out more about echinacea and other biologically related complementary and alternative therapies.3
Echinacea should not be used in women who are pregnant or breast-feeding and should not be administered to children younger than 2 years of age. It also is contraindicated in individuals with multiple sclerosis, HIV/AIDS, leukemia, tuberculosis, or other autoimmune disorders (ie, systemic lupus erythematosus or rheumatoid arthritis).3 Echinacea is well-tolerated?common adverse effects include dyspepsia, headache, and dizziness.
Zinc is commonly utilized by many patients with colds. High local concentrations of zinc ions purportedly block the adhesion of the human rhinovirus to the nasal epithelium.1 Several studies have revealed that zinc lozenges may reduce the intensity of the symptoms associated with a cold, particularly cough, and the length of time that a cold lingers.4 Zinc is available in a variety of formulations, such as tablets, lozenges, gums, nasal sprays, and gels and swabs.
Prior to taking zinc, patients should consult their physician and pharmacist?especially those patients taking angiotensin-converting enzyme inhibitors, nonsteroidal anti-inflammatory drugs, immunosuppressant agents, quinolones, tetracyclines, or hormone replacement therapy.4 Common side effects of zinc usage include gastrointestinal effects, such as nausea and vomiting, and dysgeusia (a metallic taste in the mouth).
Studies have shown that large doses of vitamin C (>1 g per day) started early in the course of the common cold may decrease the duration of the cold slightly (<1 day) and may decrease the severity of the symptoms by approximately 20%.1 The clinical risk and the risk versus benefits of this therapy are still up for debate among health care professionals.1 Pharmacists should inform their patients about the potential adverse effects associated with the routine use of high doses of vitamin C, which include diarrhea, increased iron absorption, kidney stones, nausea, abdominal cramping, and flatulence.3
Pharmacists should encourage their patients to discuss the use of any of these alternative therapies with their physicians prior to using them. As with the use of any medications, pharmacists should thoroughly evaluate their patients' profiles, including allergies, medication profiles, and medical histories. They also should educate patients on the proper uses of these agents, their adverse effects, possible drug interactions, and all precautions regarding their use. For more information on the recent developments regarding echinacea, visit the National Center for Complementary and Alternative Medicine Web site at www.nccam.nih.gov.
Ms. Terrie is a clinical pharmacy writer based in the northern Virginia area.
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