 [ Symptoms ] my 7 year old takes an otc antihistamine and steroid nasal spray but still has a cough can i give her cough syrup [ Disease ] i can tell you that there are no negative drug interactions between dextromethorphan antihistamines and steroid nasal sprays but i cannot tell you at this time if dextromethorphan is the best product to use for your daughter is type of cough i suggest you talk with your health care professional who will collect more information from you and make a recommendation