Your mother must be having mild asthma
or hypereactive airways which may have got aggravated in the cold weather. Inhaler medicines are the mainstay of treatment of asthma and she should take inhalers which have combination of long acting beta agonists like salmetrol/formetrol and a long acting steroid
. Beside this, she can take a antileukotrein like monteleukast at night. If symptoms are still not controlled, she may take doxyphyllin 400 mgm twice a day instead of deriphyllin
. Take precautions against cold and avoid allergens as much as possible.