For children under age six months, over-the-counter allergy medications should not be given unless directed by your doctor. Allergies are uncommon in this age group, so if you feel that your baby is suffering from allergies, a call to the doctor would be a good idea anyway.
Saline (salt water) nose drops or nose spray does not contain any medicine and can be used safely to rinse out allergy-causing pollen from the nose and to help keep nasal passages open and moist.
Prescription allergy medications generally are not recommended for children under six months of age (and are usually not necessary, as allergies are uncommon in this age group.) Talk to your doctor if you feel that your baby is suffering from allergies.