US Pharm. 2017;41(4):8-10.
The common cold is an acute, self-limiting viral infection of the upper respiratory tract; although more than 200 viruses have been implicated, rhinoviruses cause most cases.1 Symptoms of the common cold include fever, nasal discharge and congestion, cough, and sore throat.2 These usually present 1 to 2 days after exposure to the virus and typically last for 7 to 10 days, with some symptoms persisting for up to 3 weeks.2 The incidence of the common cold declines with increasing age; children usually have six to eight colds per year, adults younger than age 60 years typically have two to four colds per year, while adults older than age 60 years usually have one cold per year.2 Stress and lack of sleep may increase the risk of the common cold in adults, whereas daycare and school attendance may increase the risk in children.3 In most cases, the common cold does not cause serious illness or complications; however, patients with comorbidities may be at a higher risk for complications, including exacerbations of asthma, chronic obstructive pulmonary disease, and pneumonia.
The common cold is the leading cause of missed work and school days during the winter months. Although there is no known cure, many patients seek nonprescription medications for symptom relief, spending over $8 billion on cough and cold products in 2016.4 In addition to the various nonprescription medications available, many vitamins, supplements, and herbal preparations are promoted for the prevention and treatment of the common cold. The use of complementary and alternative medicine (CAM) is gaining popularity for the treatment of a variety of conditions, including a head or chest cold—one of the top 10 conditions.5 Because there are a multitude of products available OTC that are advertised for the prevention and treatment of the common cold, pharmacists frequently receive questions about the safety and effectiveness of these remedies.
Echinacea
Echinacea is probably the most common herbal supplement associated with the prevention and treatment of colds. This plant is promoted as an immune-system stimulant. There are three different species of Echinacea currently used for medicinal purposes: Echinacea purpurea, Echinacea pallida, and Echinacea angustifolia, as well as different segments of the plant.6 These differences, along with variations used in extraction methods, has led to clinical trial results with unclear evidence of their effectiveness against the common cold.
A 2013 Cochrane Review evaluated the effectiveness of Echinacea compared with placebo for the prevention and treatment of the common cold.6 The authors concluded that Echinacea demonstrated no benefit for the treatment of colds, and prophylactic treatment did not significantly reduce their incidence. Echinacea is available in various dosage forms, including tablets and capsules, oral extracts, juices, and teas, leading to differences in composition and formulations. Although Echinacea should not be recommended for the prevention or treatment of colds based on evidence, if patients still want to use a product, E purpura may provide more benefit compared to the other species.6
Echinacea is usually well tolerated, with few adverse events. Most commonly, gastrointestinal upset, headache, and rash occur. Its use is also associated with a tingling sensation of the tongue and an unpleasant taste. Severe allergic reactions have also been reported; if patients have a severe allergy to the Asteraceae/Compositae family, which includes ragweed and chrysanthemums, Echinacea use is contraindicated. It is also suggested that patients who are immunocompromised or have an autoimmune disease should avoid Echinacea.7 Echinacea may inhibit cytochrome P450 1A2 and induce P450 3A4, but the clinical significance of this effect is unclear.8
Elderberry
Elderberry, or Sambucus nigra, is commonly used for treating symptoms related to the flu. It is thought to have antioxidant and immune-modulating properties.9,10 There is evidence to suggest that elderberry does reduce symptoms of the flu.11,12 In one study, elderberry extract was used daily for 3 days and then monitored for 6 days in patients reporting influenza symptoms during an outbreak of influenza B.11 After 3 days, complete symptom resolution was demonstrated in 46.7% of elderberry-treated patients and in 16.7% of placebo-treated patients. The second study was conducted during an influenza A epidemic.12 Elderberry was administered four times daily for 5 days. Most patients in the treatment group reported “pronounced improvement” within 3 to 4 days compared with the placebo group, which reached the same level of improvement within 7 to 8 days. It is important to note that both of these studies used a specific elderberry product, Sambucol; these results should not be extrapolated to all elderberry products. In addition, both studies consisted of small sample sizes, limiting the generalizability of the results.
Elderberry is well tolerated and there are very few reports of adverse effects with usage. Patients should be warned not to eat raw or insufficiently cooked elderberries; cyanogenic glycosides are metabolized to cyanide in the GI tract, causing nausea, vomiting, dizziness, weakness, and stupor.10
Garlic
Many patients take garlic as a preventative for the common cold. It is thought to have antibacterial and antiviral properties. Studies demonstrating its efficacy against the cold and flu are limited. A Cochrane Review only identified one trial suggesting that the daily prophylactic use of garlic may decrease the incidence of a cold.13 There is currently no evidence to suggest that garlic will reduce the symptom severity or illness duration associated with the common cold.
Although generally well tolerated, garlic is associated with bad breath and body odor. It may also cause nausea, vomiting, and heartburn. It is associated with antiplatelet activity and can increase prothrombin time; caution should be used in patients taking warfarin or antiplatelet agents.
Ginseng
Both American ginseng (Panax quinquefolium) and Asian ginseng (Panax ginseng) have been evaluated for their use in upper-respiratory infections. Evidence indicates taking a specific extract of American ginseng, CVT-E002, demonstrates possible efficacy.14 If taken daily over a period of 3 to 4 months during influenza season, the risk of developing a cold or flu may be decreased; when infection does occur, symptom severity and duration are reduced. This extract also appears to reduce the number of colds in a season.15 Evidence also suggests that taking a specific Asian ginseng extract (G115) daily 4 weeks prior to influenza vaccination increases antibody titers and decreases the occurrence of flu.16
Few adverse effects have been reported with ginseng use. Headache is mostly commonly associated with American ginseng, and insomnia has been associated with Asian ginseng.16 Both agents affect platelet aggregation; they should be avoided in patients concomitantly taking warfarin and other antiplatelet agents.
Pelargonium Sidoides
Pelargonium, otherwise known as Umckaloabo, Umcka, Kaloba, or Zucol, is an herbal remedy derived from the roots of P sidoides.17 Extracts of Pelargonium have been promoted for a variety of respiratory conditions, including bronchitis, sinusitis, tonsillopharyngitis, otitis media, and the common cold.18 The herbal extract is hypothesized to have several physiologic effects, including weak antibacterial properties, inhibition of viral adherence, immunomodulation, and mucolytic effects.
The efficacy of a liquid preparation of Pelargonium in managing cold symptoms was evaluated in a well-designed trial.19 Patients receiving Pelargonium demonstrated significant improvement of symptoms from baseline to Day 5. In addition, 78.8% of Pelargonium-treated patients were considered “cured” after 10 days of therapy compared with 31.4% of those receiving placebo. The authors concluded that this herbal significantly reduces the duration of a cold and ameliorates the severity of cold symptoms.
A 2013 Cochrane Review evaluated the efficacy of Pelargonium compared to placebo in the treatment of various acute respiratory tract infections.18 Overall, the authors considered the quality and depth of the evidence supporting the use of Pelargonium for the treatment of common respiratory infections, including the cold, to be low. As such, they believe that there is limited evidence to fully demonstrate the effectiveness of this herbal in the treatment of the cold or other common respiratory diseases.
Pelargonium is generally well tolerated. There have been few reports of gastrointestinal irritation, conjunctivitis, and itchy rash with accompanying angioedema and systemic involvement. Patients who are immunocompromised or suffer from an autoimmune disease should avoid its use; the immunostimulant effects can worsen these disease states.8 Concerns regarding the safety of Pelargonium have been raised as extracts of this herbal contain naturally occurring coumarins, which may interfere with clotting, resulting in hemorrhagic complications.
Vitamin C (Ascorbic Acid)
Vitamin C is a water-soluble vitamin that has an important role in various physiological processes. There have been a significant number of clinical studies completed to determine the efficacy of vitamin C treatment in the common cold. Overall, vitamin C failed to demonstrate any reduction in the incidence of colds in the general population.20 However, regular supplementation may decrease the duration of a cold: 8% shorter in adults and 14% shorter in children.20 Many patients may also begin taking high doses of vitamin C after the onset of symptoms; however, data have not shown consistent effect on the duration or severity of symptoms.20
At doses used for daily supplementation, vitamin C is generally well tolerated. Patients who take very high doses of vitamin C must gradually reduce the dose to avoid rebound scurvy symptoms.
Zinc
Zinc is a mineral that is considered an essential nutrient. Studies have shown that a mild zinc deficiency can elicit changes in the patient’s immune status, increasing their risk for infection.21 Zinc has also been shown to inhibit replication of the cold virus. Because of these effects, zinc supplements are thought to be effective in preventing and treating the common cold.
There has been inconsistent evidence with regard to the effectiveness of zinc to reduce the duration and severity of the common cold.22,23 This inconsistency may be due to the variation in the preparations, including the type of zinc, amount of zinc used, and composition of the products. One meta-analysis has demonstrated possible effectiveness of oral zinc supplementation for at least 5 months in preventing colds in children.23 Zinc lozenges at doses >75 mg/day have been shown to be effective in reducing the duration of symptoms in adults by approximately 1 to 3 days if initiated within 24 hours of symptom onset.22-24
Oral zinc supplements, especially at doses greater than 40 mg, can cause stomach upset. Prolonged use can lead to copper deficiency. Intranasal zinc has been associated with anosmia. In 2009, the FDA issued a warning to stop using zinc-containing intranasal products. Since then, many of these products have been reformulated, but patients should still be advised to avoid intranasal zinc.
Conclusion
Although self-limiting, the common cold is associated with troublesome symptoms. There is a plethora of herbal products and supplements available claiming to be effective in preventing and treating the common cold. Most of the evidence available is inconsistent and demonstrated small effects.
Based on the available data, American ginseng may decrease the risk of catching a cold. Daily vitamin C supplementation may potentially be beneficial in reducing cold symptoms. Oral zinc lozenges in doses of >75 mg/day demonstrated decreased symptom duration. Although evidence for Echinacea was not conclusive, many patients still utilize this agent; E purpurea should be the recommended species. When providing information to patients, it is important to remember that the FDA does not recommend these agents and there may be inconsistencies between manufacturers and batches. Pharmacists are in a vital position to help patients make informed decisions regarding the use of such products.
PATIENT INFORMATION
What causes the common cold?
The common cold is caused by a virus. The most common virus is the rhinovirus. You catch a cold from someone who is already sick. This can happen by touching surfaces that are contaminated with the virus or by direct contact with the infected person.
What are the symptoms?
The common cold usually causes nasal congestion, runny nose, and sneezing. You may also have a scratchy throat, headaches, and muscle aches; you may feel tired; and you may have a low-grade fever. If a cough occurs, it usually happens on the fourth or fifth day.
What can I do if I have a cold?
• Drink plenty of fluids.
• Get plenty of rest.
• Humidify the air.
Are there any treatments for the cold?
There is no cure for the common cold, but there are medications that can help relieve some of the symptoms. Before you use any product, you should speak with a healthcare provider.
• Nasal/sinus congestion: use a decongestant, such as pseudoephedrine
• Runny nose: use an antihistamine and various nasal inhalers such as NasalCrom and Flonase
• Fever, sore throat/headache/body aches: use a mild pain reliever such as acetaminophen or nonsteroidal anti-inflammatory agent such as ibuprofen or naproxen
• Cough: common ingredients include guaifenesin and dextromethorphan
Are there any herbals or vitamins I can use?
Although many products such as vitamin C, zinc, and Echinacea have been advertised to prevent and treat the common cold, studies have not shown these products to work. There use is not routinely recommended.
How can I prevent a cold?
• Wash your hands after touching surfaces, before preparing food and eating, and before touching your face, eyes, nose, or mouth.
• Sneeze or cough into your crooked elbow and use tissues. Wash your hands after.
• Do not share drinks or eating utensils.
REFERENCES
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