Hi, Noted the history about your wife having dry cough for hte last 7 months, has known allergic rhinitis, her mother has history of allergic skin problem and the daughter having similar problems; X-ray chest and PFT that is pulmonary functions tests already done and are normal. Since PFT is normal the cause may not be bronchial asthma. With the positive history of allergy, the cause may be related to allergic component in the throat causing irritation and thus the dry coughing. Many a times the persistent cough can have stress and anxiety as as cause. I would advise her to see an ENT Surgeon proper proper clinical evaluation, ENT Endoscopy and further investigations if any. This may give a proper cause and thus allow a proper management. Plain anti-tussive or cough suppressants may be tried with oral course of steroids in tapering doses. Also identify the factors that instigate or enhance coughing like working in kitchen, gardening, dusting and avoid all these things as prevention is better than cure. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, ENT & General Surgeon