Jenny A. Van Amburgh, PharmD, CDE


May 03, 2013


What is the efficacy of pharmacologic and non-pharmacologic cough medications?

Response from Jenny A. Van Amburgh, PharmD, CDE, Assistant Dean of Academic Affairs; Associate Clinical Professor, School of Pharmacy, Northeastern University; Director, Clinical Pharmacy Team Director, Residency Program, Harbor Health Services, Inc., Boston, Massachusetts

Most coughs are transient. However, prolonged coughs may warrant cough medicine or nonmedicinal management. The most common pharmacologic agents are centrally acting cough suppressants (eg, dextromethorphan and codeine), peripherally acting cough suppressants (eg, benzonatate), and expectorants (eg, guaifenesin). Popular nonpharmacologic approaches include vapors (eg, menthol) and honey. Although these agents are commonly recommended, information on the efficacy of cough medicines has been drawn from limited small trials with weak methodologies.

Studies involving use of dextromethorphan in children have reported no clinically significant difference in symptoms of cough compared with placebo.[1] This lack of effect is not affected by dose, because studies of higher doses of dextromethorphan have also reported no difference in symptoms.[2] In adult patients with upper respiratory infection, there is no added benefit of using dextromethorphan or codeine.[3,4] One older study found that dextromethorphan may be a better alternative to codeine.[5]

The efficacy of benzonatate, a cough suppressant that provides symptomatic relief of cough by anesthetizing the respiratory passages, has been shown in case studies only with patients who have cancer. Thus, it is not a reliable option for all patients.[6]

Other cough medications include guaifenesin, an expectorant that decreases the viscosity of sputum to promote a productive cough. Unlike for dextromethorphan, clinically significant evidence exists to support claims that guaifenesin decreases sputum quantity and thickness.[7,8]

Menthol is a mild anesthetic that provides a cooling sensation when used as a cough drop. Recent studies[9,10,11] have focused on patients inhaling vaporized solutions with menthol to help with coughing.These studies show that inhaling menthol can increase the cough threshold and thus reduce sensitivity to cough.Although commonly used, lozenges, ointments, and creams containing menthol have not been studied.

Nonpharmacologic options, such as honey, may soothe coughs. Randomized controlled trials found that honey was significantly better than placebo at reducing symptoms of cough.[12,13,14,15] Currently, the evidence for or against the use of honey for patients with cough is limited. The American Academy of Pediatrics does not recommend honey or any products containing honey in infants younger than 1 year, because there is a higher risk for botulism in this population.[16]

Data on the efficacy of cough suppressants, vapors, and expectorants for decreasing the frequency or duration of cough are lacking. It is important to inform patients that most coughs will resolve in a couple of weeks. Nonpharmacologic recommendations to help soothe coughs include hydration, nonmedicated lozenges, and cool-mist humidifiers. A cough that involves thick yellow or green phlegm, unintended weight loss, fever > 101.5° F, nighttime sweats, coughing up blood, or underlying diseases (eg, chronic obstructive pulmonary disease, bronchitis, or chronic heart failure), or one that lasts more than or worsens after 7 days of treatment, should be investigated further by a healthcare provider.[17]

The author wishes to acknowledge the assistance of Ngoc Diem Nguyen, PharmD; Jacqueline M. Kraft, PharmD; and Phillipa Scheele, PharmD, PGY1 Residents, and Nga T. Pham, PharmD, CDE, AE-C, Clinical Pharmacist at Lancaster General Health, Lancaster, Pennsylvania.