Our doctor prescribed epipen (epinephrine) jr for our son who is allergic to peanuts. Our son is now 55 lbs. Do we need the epipen (epinephrine) for adults for them?

EpiPen (epinephrine) Dosing. According to epocrates, the adult sized Epipen (epinephrine) is used in children greater than 30kg, or 66 lbs. If your son is 55lbs, he needs to grow a little more before you move him up.