My doctor wants to start me on monthly IVIG infusions to boost my immune system. My IGG levels remain in the 200's range due to myeloma treatment. I have read the long list of possible side effects. If you receive IVIG infusions, can you share your experience. I know that pre-medication with Benadryl and Tylenol is standard. I cannot take Benadryl due to a paradoxical reaction, so my doctor is recommending Zyrtec. If you pre-medicate with Zyrtec, what is the dosage? z