 [ Symptoms ] can i give my 3 year old daughter childrens claritin and a decongestion med within 24 hours of each other  the decongestion medicine in a prescription medicine that was given to her for congestion problems in the past but i am not sure if her stuffy nose and cough is now from pollen and seasonal allergies [ Disease ] decongestants can be used with antihistamines or separately as long as the dosgages are appropriate newer recommendations do not support the use of these types of drugs for children under the age of six unless specifically prescribed and approved by the child is medical provider decongestants have not proven to be very effective in the management of colds and do not help children with allergies antihistamines can be helpful for allergies however but again it is best to get the okay from your child is pediatrician because of the age