Testing prior to initiating commonly impacted drugs helps to identify patients at high risk for severe drug-induced hypersensitivity reactions. Testing should be considered for individuals with a personal or family history of adverse drug effects to abacavir (Ziagen®), allopurinol (Zyloprim®), and carbamazepine (Tegretol®). Testing should be done to confirm the presence of genotypes that affect the sensitivity to specific medications.

Patients initiating carbamazepine therapy may benefit from HLA-A*3101 testing. All patients of Asian ethnicity should be tested for the HLA-B*15:02 allele prior to phenytoin (Dilantin®), and carbamazepine (Tegretol®).  and fosphenytoin (Cerebyx®) administration. Patients of all ethnicities should be tested for HLA-B*57:01 rs2395029 (LD) prior to abacavir administration due to incidence of hypersensitivity. All patients should be tested for HLA-B*58:01 prior to allopurinol therapy due to severe cutaneous reactions.^[51] Assessment of medical necessity for testing is up to the provider’s clinical judgment.