Hi Mrs. Shweta Sharma, Thank you for posting your querry on healthcaremagic.com and giving us this opportunity to clarify your doubt. Well, the fact that your daughter has this allergic cough since past 1 month, which responds to anti-allergens, and history of allergy to citrus fruits all dictate that her cough might be some form of an asthma- probably a mild variant. At this point of time, i would like to ask if there were any similar episodes in the past, any family history of allergy or asthma, any other specific history of diseases running in the family, any pets at home or any specific seasonal association of this kind of cough? If any of these questions are answered as yes, it again points towards asthma. 3 years can be an age for it to begin, since children starting getting exposed to newer and newer environmental pollutants now. If her symptoms persist, it would be advisable for you to consult the nearest peadiatric pulmonologist / pediatrician in order to keep a close follow up with them and you might also have to do a few tests. I hope i have satisfactorily answered your questions and will be open for any further doubts. Take care and stay healthy.