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As hemopathic and alternative remedies for minimizing cold symptoms become more popular with patients, pharmacists should be familiar with their safety and efficacy.
In an effort to prevent or reduce symptoms of the common cold, many patients are turning to complementary and alternative therapies. As use of these therapies becomes increasingly common, pharmacists are likely to encounter questions from patients regarding their safety and efficacy. According to the National Institutes of Health’s National Center for Complementary and Alternative Medicine (NCCAM), colds are the eighth most common condition among adults— and the third among children—for which alternative and complementary therapies are used to prevent and manage symptoms.1
To date, there is no conclusive scientific evidence stating that any CAM therapies can prevent or significantly decrease the duration or severity of the common cold.1 Although some studies have reported possible benefits, the overall findings regarding specific CAM therapies are limited and the evidence is conflicting.1,2 Research is ongoing to investigate the potential use of CAM therapies in the prevention and management of the common cold.1,2
Among the complementary products most often used to help prevent and manage symptoms of the common cold are echinacea, high-dose vitamin C, and zinc lozenges.2 Other products available include andrographis panicula, astragalus membranaceus, elderberry, garlic, goldenseal, North American ginseng, and probiotics.1
Patients also utilize products formulated to strengthen the immune system, such as Airborne tablets (Airborne, Inc), which include a combination of vitamins, minerals, amino acids, and herbs to support immune health.2 The manufacturer suggests that patients use these products before entering crowded or poorly ventilated environments such as an airplane or classroom. Although these CAM products are commonly used, their safety and efficacy have not yet been proved.2 They are available in chewable form, as effervescent tablets, and as single-dose packets that are taken with water.
Echinacea (Echinacea purpurea, Echinacea angustifolia) has traditionally been used to prevent or treat colds, influenza, and other types of infections, and is thought to stimulate the immune system. There are 9 known species of this herb, all of which are native to the United States and southern Canada.3 Echinacea is available in several forms, including extracts, tinctures, tablets, capsules, and teas. A study published in the December 2010 issue of the Annals of Internal Medicine found that echinacea had no effect on reducing the severity or duration of the common cold.4 However, a 2007 meta-analysis of 14 controlled trials in adults concluded that E purpurea taken prophylactically decreased the odds of developing the common cold by as much as 58% and decreased the duration of a cold by 1.4 days—both of which were considered to be statistically significant.5
In clinical trials, gastrointestinal issues were the most commonly reported adverse events; others included headache, dizziness, temporary numbing of the tongue, and dyspepsia.6 Pharmacists should advise patients with severe systemic illnesses such as HIV/AIDS, multiple sclerosis, tuberculosis, and autoimmune disorders, including rheumatoid arthritis, to avoid the use of echinacea.6-8 Individuals who are allergic to or have a hypersensitivity to ragweed, daisies, or chrysanthemums should avoid also avoid this therapy due to the potential for crosssensitivity. 7,8
Zinc is a trace element found in several OTC alternative medicine products marketed for prevention and management of the common cold. To date, the effect of zinc in reducing the severity and duration of common cold symptoms has not been established.9 However, a 2011 review published in the Cochrane Database of Systemic Reviews reported that zinc lozenges and zinc syrup were shown to reduce the duration and severity of the common cold when taken within the first 24 hours of symptom onset.9,10
Results from a meta-analysis published in the July 2011 issue of The Open Respiratory Medicine Journal found that high-dose, and not low-dose, zinc lozenges may shorten the duration of the common cold.11 The study concluded that depending upon the dosage and composition of zinc lozenges, use of these products may reduce the duration of a common cold by an estimated 40%.10 A 2009 review reported that doses exceeding 70 mg per day consistently decreased the duration of colds; however, additional research is needed to determine the optimal dosage and treatment guidelines, according to NCCAM.1
Zinc is available in several forms, including lozenges, tablets, and capsules, and nasal gels, sprays, and swabs. Nausea, vomiting, and dysgeusia are the most common adverse effects associated with the use of oral zinc formulations.2 Because zinc is a trace metal and therefore can remove other necessary metals from the body, zinc lozenges should not be taken for more than 14 days.12 It is important to note that zinc can interfere with the absorption of certain pharmacologic agents such as warfarin, doxycycline, and minocycline.13
In patients using nasal sprays, headaches, dry mouth, nasal stinging or burning, and anosmia (loss of smell) are the most common adverse effects.2 In 2009, the FDA issued a warning regarding the use of zinc-containing intranasal homeopathic cold remedy products because of the potential to cause anosmia.6
Vitamin C is often utilized by patients to boost the immune system.14 Results from a 2007 analysis of 30 clinical trials founds that taking vitamin C routinely (at least 0.2 g per day) did not decrease the likelihood of getting a cold,1 but was associated with a small decrease in the severity of symptoms and duration of the common cold.1 A 2009 review examining the effects of vitamins and minerals on colds concluded that supplementation with vitamin C does have some potential benefits in treating the common cold. However, due to the limited number of therapeutic trials, more research is needed to ascertain effective dosage amounts and develop treatment guidelines.1 At the present time, there are no studies that focus on the pediatric population.1
Although vitamin C is generally considered to be safe, adverse effects have been reported when it is taken in high doses.1 For example, individuals who take 4 g or more per day have reported experiencing diarrhea and other gastrointestinal issues, such as heartburn, and therefore high doses are not recommended.1 Other potential adverse effects include headache, dizziness, and fatigue.15 Patients should be advised to drink a full glass of water when taking vitamin C supplements to prevent the development of kidney stones.15
Patients—especially those who are pregnant, breast-feeding, or currently taking any other pharmacologic agents, or members of the pediatric and geriatric patient populations and their caregivers—should be advised to discuss the use of complementary and alternative therapies with their primary health care provider before using them for the prevention and management of the common cold.
For more information on CAM products, please visit NCCAM’s Web site at http://nccam.nih.gov/. PT
Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.
1. Colds and flu and cam: at a glance. National Institutes of Health National Center for Complementary and Alternative Medicine Web site. http://nccam.nih.gov/health/flu/ataglance.htm. Accessed September 14, 2011.
2. Scolaro K. Disorders related to colds and allergy. In: Berardi R, Newton G, McDermott JH, et al. Handbook of Nonprescription Drugs. 16th ed. Washington, DC: American Pharmacists Association; 2009.
3. Echinacea. National Institutes of Health National Center for Complementary and Alternative Medicine Web site. http://nccam.nih.gov/health/echinacea/ataglance.htm. Accessed September 14, 2011.
4. Barrett B, Brown R, Rakel D, et al. Echinacea for treating the common cold. Annals of Internal Medicine. 2010;153:769-777.
5. Shah SA, Sander S, White CM, Rinaldi M, Coleman CI. Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis. Lancet Infect Dis. 2007;7:473-480. Abstract.
6. McQueen C, Orr K. Natural products. In: Berardi R, Newton G, McDermott JH, et al. Handbook of Nonprescription Drugs. 16th ed. Washington, DC: American Pharmacists Association; 2009:991-992.
7. Echinacea drug facts. Drug Information Web site. www.drugs.com/npp/echinacea.html.Accessed September 15, 2011.
8. Echinacea drug information. Medscape Drug Reference. http://reference.medscape.com/drug/black-sampson-black-susans-echinacea-344472#5.Accessed September 15, 2011.
9. Zinc and the common cold. National Institutes of Health National Center for Complementary and Alternative Medicine Web site. http://nccam.nih.gov/health/zinc/. Accessed September 14, 2011.
10. Singh M, Das RR. Zinc for the common cold.Cochrane Database of Systematic Reviews. 2011, Issue 2. Art. No.: CD001364.pub3. doi:10.1002/14651858. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD001364.pub3/abstract. Accessed September 14, 2011.
11. Barclay L. High dose zinc lozenges may reduce duration of cold symptoms. Medscape Web site. www.medscape.com/viewarticle/747426. Accessed September 14, 2011.
12. Zinc. Merck Manual for Healthcare Professionals Online Edition. www.merckmanuals.com/professional/special_subjects/dietary_supplements/zinc.html. Accessed September 14, 2011.
13. Cold EEZE Product Information. Cold EEZE Web site. www.coldeeze.com/faq/#nul. Accessed September 14, 2011.
14. Kemper K. Complementary and alternative medicine therapies for cold and flu season: what is the science? Medscape Web site. www.medscape.com/viewarticle/711485_3. Accessed September 14, 2011.
15. Ascorbic acid drug information. Medscape Drug Information.http://reference.medscape.com/drug/cenolate-vitamin-c-ascorbic-acid-344416#91. Accessed September 15, 2011.