How much Benadryl

AB

Do you give your LO Benadryl when they have an allergic reaction to certain food? My Pedetrician said to start giving him eggs,

Peanut butter and fish and if he develop some rashes then give him Benadryl but forgot to ask how much since it’s children’s Benadryl so I’m not sure how much to give to an infant. He’s 6 months old