Cold medicines are off-limits this young. If you are breastfeeding, breastmilk in the nose is a great decongestant. Otherwise, a humidifier in the room. You CAN use an external like vapo-rub. Just nothing INSIDE.
at this young age natural remedies is all you can do. cool mist humidifier in the baby's room 9or steam the bathroom with a hot shower), bulb syringe or saline drops to clear the mucous. Dont offer any over the counter medicine.