Pharmacogenomics is the study of the role of the genome in drug response. Its name reflects its combining of pharmacology and genomics. Pharmacogenomics analyzes how the genetic makeup of an individual affects his/her response to drugs. One current use of pharmacogenomics involves people infected with the human immunodeficiency virus (HIV). Before prescribing the antiviral drug abacavir (Ziagen), doctors now routinely test HIV-infected patients for a genetic variant that makes them more likely to have a bad reaction to the drug. This relatively new field combines pharmacology (the science of drugs) and genomics (the study of genes and their functions) to develop effective, safe medications and doses that will be tailored to a person's genetic makeup. Pharmacogenomics is an important example of the field of precision medicine, which aims to tailor medical treatment to each person or to a group of people. Pharmacogenomics can improve your health by helping you know ahead of time whether a drug is likely to benefit you and be safe for you to take. Its long-term goal is to help doctors select the drugs and doses best suited for each person.