Suggest Treatment For Allergic Cough

Constant cough with my 40 year old wife who keeps getting this allergic cough every now and then in this dusty place of bangalore. everytime she gets well with montair lc. she takes one tablet in night. In 34/4 days she gets ok usually. today she is coughing just way too much! I am thinking to give her 2 tablets in a day. Will that be ok?