Predicting the clinical results of various treatments in various patients and offering tailored care are the two main objectives of personalised medicine. One of the fundamental components of personalised medicine is pharmacogenomics. By customising drug selection and dosage to each patient’s unique genetic profile, the study of pharmacogenomics—which studies how a person’s genetic composition affects how they react to medications. It plays a critical part in personalised medicine. By maximising medication efficacy and minimising side effects, this strategy seeks to provide safer and more effective treatments. The fundamental idea is that a variety of factors, such as genetics, epigenomics, the environment, and a patient’s attributes, such as gender, age, and concurrent medicine, can result in interindividual variability in drug response. By using this information, medical professionals can maximise treatment results by selecting the best medication and dosage for each patient. Pharmacogenomics can enhance treatment effectiveness and lower the risk of treatment failure by customising medication therapy to each patient’s unique genetic makeup. Although genetic variants in drug-metabolising enzymes were revealed to change medication response 30 years ago, more than 90% of pharmaceuticals currently used in clinical practice lack reliable and predictive biomarkers for therapeutic effects to prevent serious side effects. In recent years, pharmacogenomics has revolutionised our understanding of disease susceptibility and pathophysiology by utilising a new generation of technologies known as “omics” methods. This has greatly increased the potential for new therapeutic approaches. Pharmacogenomics unquestionably aids in the creation of targeted treatments.