Many cough syrups contain 1.4 to 5 percent alcohol. A few cough syrups contain significantly more alcohol, 10 to 40 percent. Alcohol is often included in cough syrups because it is thought to help suppress the cough reflex.
In comparison, a regular beer contains 5 percent alcohol, but a serving of beer is 12 ounces of the beverage. When consuming cough syrup, a dose is 1 ounce or less, so far less alcohol is consumed.
Most cough syrups contain a cough suppressant, such as dextromethorphan, to suppress the cough reflex. Some cough medications contain other ingredients, such as expectorants, antihistamines and decongestants.