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Pharmacy and Medications

Benadryl for Cough

11/12/2010

Question:

Hi guy, I got Benadryl in Cambodia and the label reads Expectorant. I dont understand why it is like this because in my country it is only for itching eyes or allergy condition rather than cough but when I went through the insert it contains Ammonium chloride also.

I wonder if this expectorant effect is caused by the presence of Ammonium chloride or Benadryl, as well as other antihistamines, is applicable for cough as well. Thank you.

Answer:

Medications that reduce the number of coughs or the intensity of coughing are known as antitussives.  Antitussives are further classed by where they act in the body.   Some act in the cough center of the brain and some act on nerves in the breathing tract.

Diphenhydramine is a first generation, non-selective and sedating antihistamine.   Its exact mechanism for suppressing cough is unclear but is believed to act in the cough center of the brain.
Diphenhydramine is indicated for cough from colds or allergies.

Many substances, including ammonium chloride, have been included in non-prescription expectorants.   In the United States, only Guaifensin is FDA-approved for use as an expectorant.   Other substances such as ammonium chloride may be found in non -prescription cough medicines but are considered inactive ingredients.

As diphenhydramine doesn't act as an expectorant,  the Cambodian product mentioned may be called an expectorant because it contains ammonium chloride.

Other antihistamines may not have the same action in the brain's cough center or breathing center as diphenhydramine and would be unlikely to supress cough.


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Response by:

Carmen M Hadley, RPh, CSPI
Formerly:
Clinical Instructor
College of Pharmacy
The Ohio State University