The most important consideration in today's therapy is adherence to the combination therapies to prevent mutation and resistance. At this time most health care providers are even reluctant to stop or alter combination therapies even in the presence of opportunistic infections. Each class of drugs have different mechanisms mainly geared to inhibit the reproduction of HIV from different reproductive phases of the virus. When this happens the virus can longer make RNA which would prevent replication. 2 commonly used NA's are used in combination, usually with one or more antiretroviral agents from another class.
T can cause peripheral neuropathy and pancreatitis.
AZT can cause severe bone marrow suppression. This syndrome could be fatal if the patient is desensitized to the medication. There is some concern in just using this a monotherapy due to the high level of HIV resistance in RNA replication. This class of drugs are commonly used in triple drug therapy. In rare instances, these rashes have progressed to Stevens-Johnson syndrome.