As the history which you told is very concised and the duration is pretty long . It's difficult to give a one word answer.But if he is habituated to smoking then kindly stop it . Take Luke warm water for drinking.

In a viral fever antibiotics will not play any role. He will require symptomatic management of antipyretics, antihistamines, antacid and cough syrup. The following steps may be of help: - Avoid cold food and water, preferably have hot food and water - Don't skip meals have a liquid diet containing soups and progressively increase to solid diet as per how you can tolerate. - Have food rich in vitamin C such as oranges to help build immunity. - Drink plenty of fluids, drink 3 liters of water per day - Do salt water gargling with lukewarm water thrice a day - Do steam inhalation (plain steam) thrice a day and apply vaporub over your chest and nose - Maintain good personal hygiene(Wash you hands regularly) - Rest plenty, body heals while at rest If the condition persists or worsens visit nearest ER at earliest

If cough is more than a month; It better to do investigation and confirm it. Recommended to meet a GP and get him reexamined again