 [ Symptoms ] i have had a chronic cough for several months i am taking an otc antihistamine but it is not working what next [ Disease ] common causes of cough include nasal allergy with post nasal drip acid reflux and asthma do you have nasal congestion sneezing and drip i agree that a trial of antihistamines is helpful you can consider adding on a sinus rinse and talk to your doctor about a nasal steroid spray to help decrease the drainage do you experience any heartburn symptoms do you feel short of breath i would let your doctor know if you have persistant cough as additional therapies or investigations may be warranted