Our 6-yr-old CAH daughter just went through it in the spring. This is the one virus you need to be careful about double/triple dosing (like one of the other posts mentioned....it can suppress the immune system *too* much, and you're at risk for complications from the pox taking over). We ended up only doing 1.5 times her reg dose for the fever. We actually had the Acyclovir on hand...it is an anti-viral (if there is such a thing!). It needs to be given within 24 hrs to, hopefully, keep the virus in check. She came through it fine....do Tylenol, not motrin...(ibuprofen can act too much like aspirin for this virus and there's the remote chance of Reye's syndrome...) I would definite alert your 2-yr-old's ped endo....get the Acyclovir. Kare