Serum Sickness

This can be caused by antigens such as penicillins, sulfas, streptomycin, and other drugs. The illness occurs some 5 to 7 days after ingestion and is manifested by fever, rash, joint pains, swollen lymph glands, and sometimes, kidney inflammation (nephritis). It is caused by the antigen and an antibody bonding in clumps (‘complexes’) and being deposited in various parts of the body. Treatment is with steroids.

http://en.wikipedia.org/wiki/Serum_sickness