My father-in-law is on regular prescribed dosage of Acitrom 2mg + Lanoxin 0.25mg + Seloken 25mg + Ramistar 2.5mg sine he has Atrial Fibrillation (on medication for over 4 years now). A couple of days ago, due to cold weather, he got common cold and has a slight but building cough. I would like to know whether he needs to stop or change dosage of his existing medication if he takes over-the-counter medication (like Sinarest) to cure his common cold.