Does it happen every time you take
valacyclovir and stay there. If the rash is due to VCV, it should not come
and go as long as you are taking the drug?
Drug allergies may be either specific to the drug being taken or it may occur within a class of drugs. Thus, if this is a valacyclovir reaction, you might not react to famciclovir (you would however be likely to react to acyclovir since VCV turns into acyclovir within the body).
Finally, you state you cannot live without VCV. Why is this?