My baby 1 months have runny and blocked nose and the mucous come back when he was sleep and he use dimethinden oral drops and saline nasal drops and no benefit?

How long?: Although a 1- month old baby tends to have resistance to infection, he is not entirely immune to a cold. If this has been present for just a few days. keep on doing what you have been doing. However if this has been present for >10 days or getting worse, I would ask the doctor to check him out. Certainly food allergy needs be considered if he is fed artificial formula.