Q: In case of viral infection and upper respiratory tract infection in an infant (9 months old), how long can we can wait to start antibiotics even if the doctor has prescribed them.

A:Antibiotics are of no use in viral infections including upper respiratory tract infection. However, at times it is clinically difficult to differentiate a viral from bacterial infection and antibiotics are often prescribed to safeguard against this possibility. In an uncomplicated upper respiratory infection, antibiotics may be indicated if the infection lasts beyond seven days and if it is accompanied by purulent (pus like as opposed to clear watery or thin) nasal discharge.