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Cough medicine often contains cough suppressants or expectorants.

A cough medicine or linctus when in syrup form is a medicinal drug used in an attempt to treat coughing and related conditions. For dry coughs treatments with cough suppressants (antitussives) may be attempted to suppress the body's urge to cough, while productive coughs (coughs that produce phlegm) treatment is attempted with expectorants that loosen mucus from the respiratory tract.

Even though they are used by 10% of American children weekly they are not recommended in children 6 years of age and under due to lack of evidence showing effect and concerns of harm.^[1][2]

[edit] Examples

[edit] Pharmaceuticals

Dextromethorphan

Dextromethorphan (DM) may be modestly effective in decreasing cough in adults with viral upper respiratory infections. In children however it has not been found to be effective.^[3]

Codeine

Codeine is claimed to be one of the strongest cough suppressants.^[4] Evidence to support this is however weak with a recent placebo controlled trial finding that codeine was no better than placebo.^[5]

Others

Other commercially available treatments have not been shown to be effective in viral upper respirtory infections including in adults: antihistamines, antihistamine-decongestant combinations, and guaifenesin and in children antihistamines, decongestants, DM, or combinations of them.^[3]

No over the counter cough medicines have been found to be effective in pneumonia.^[6]

[edit] Alternative medicine

Honey may be an effective treatment of cough. Buckwheat honey given before bedtime provided better cough relief at night and improved sleep difficulty in children more than no treatment or dextromethorphan.^[7]

Many alternative treatments are used to treat the common cold. A 2007 review however states that, "Complementary and alternative therapies (i.e., Echinacea, vitamin C, and zinc) are not recommended for treating common cold symptoms... Vitamin C prophylaxis may modestly reduce the duration and severity of the common cold in the general population and may reduce the incidence of the illness in persons exposed to physical and environmental stresses."^[8]

A 2009 review found that the evidence supporting the effectiveness of zinc is mixed with respect to cough^[3] and a 1999 Cochrane review found the evidence of benefit in the common cold inconclusive.^[9] A 2003 review however concluded: Clinical trial data support the value of zinc in reducing the duration and severity of symptoms of the common cold when administered within 24 hours of the onset of common cold symptoms.^[10] Nasally applied zinc gel may lead to loss of smell. The FDA therefore discourages their use.^[11]

A review of sixteen trials of echinacea was done by the Cochrane Collaboration in 2006 and found mixed results. All three trials that looked at prevention were negative. Comparisons of echinacea as treatment found a significant effect in nine tirals, a trend in one, and no difference in six trials. The authors state in their conclusion: "Echinacea preparations tested in clinical trials differ greatly. There is some evidence that preparations based on the aerial parts of Echinacea purpurea might be effective for the early treatment of colds in adults but results are not fully consistent. Beneficial effects of other Echinacea preparations, and for preventative purposes might exist but have not been shown in independently replicated, rigorous randomized trials.". ^[12] A review in 2007 found an overall benefit from echinacea for the common cold^[13] however further analysis found problems with the interpretations of this review.^[14]

While a number of plants and Chinese herbs have been purported to ease cold symptoms, including ginger, garlic, hyssop, mullein, and others, scientific studies have either not been done or have been found inconclusive.^[15]

[edit] Effectiveness

Health care professionals have a long history of acceptance of cough and cold medicines,^[16] however in 2001 researchers at the University of Bristol (Schroeder & Fahey) published the results of their meta analysis in the British Medical Journal indicating that some cough medicines may be no more effective than placebos for acute coughs in adults, including coughs related to upper respiratory tract infections.^[17] In 2006, the American College of Chest Physicians published a guideline that had the dual message that many over-the-counter cough medicines are not effective and that those that are effective in treating the symptom do not treat the underlying cause; the underlying disorder emphasized by the guideline was pertussis (whooping cough) in the elderly.^[18].

The Cochrane Collaboration, an international organization that evaluates medical research, reviewed 25 studies, 17 of which involved 2,876 adults and eight of which involved 616 children. In the adult studies, six compared antitussives medicines used to relieve coughs with placebo and had variable results. Two studies compared an expectorant with placebo; one found benefits. Another two studies focusing on combinations of antihistamine and decongestants produced conflicting results, while three studies found antihistamines were no more effective than placebo in relieving cough. Three other adult studies compared combinations of drugs with placebo and showed some benefit in reducing cough; one study found that mucolytics, which break down mucus, reduced cough frequency. In studies involving children, seven — two with antitussives, two with antihistamines, two with antihistamine decongestants and one with antitussive-bronchodilator combinations — showed the drugs were no more effective than placebo. One trial tested two pediatric cough syrups and both preparations showed a ’satisfactory response’ in 46% and 56% of children compared to 21% of children in the placebo group. ^[19]

The efficacy of cough syrups for children has long been questioned by medical professionals.^{[citation needed]} A report in pharmaceutical journal Australian Prescriber found that although tests results for efficacy were inconclusive for children over 2 years of age, a number of factors including accidental overdoses and well-documented adverse effects suggested caution in the paedriatic prescription of cough syrups and medicines. ^[20] The report also noted that efficacy in children under two years was extremely limited and strongly recommended against prescription to this group based on the aforementioned health risks.

Recent studies have found that theobromine, a compound found in cacao, is more effective as a cough suppressant than prescription codeine. This compound suppresses the "itch" signal from the nerve in the back of the throat that causes the cough reflex. It is possible to get an effective dose (1 g, though 0.5 g may be sufficient)^[21] from 50g of dark chocolate, which contains 2 to 10 times more cacao than milk chocolate. Cocoa powder contains roughly 0.1 g per tablespoon (5g).^[22] Theobromine was also free from side effects in the blind tests.^[23]

[edit] Mass poisonings due to diethylene glycol

According to the New York Times, at least eight mass poisonings have occurred as a result of counterfeit cough syrup, substituting inexpensive diethylene glycol in place of glycerin. In May 2007, 365 deaths were reported in Panama, which were associated with cough syrup containing diethylene glycol.^[24]

[edit] See also

• Cough drop

[edit] References

[edit] External links

• Cough medicines not helpful - from CNN.com