A new study from Queen Mary University of London found that 9% of all reported adverse drug reactions (ADRs) reported to the UK medicines regulator are associated with medications where side effect risk is partly dependent on the patient's genes. Of this subset of ADRs, 75% were associated with only three genes that impact how the body processes medication. Genetic testing before prescribing could therefore help avoid ADRs in these cases.

Over the past 60 years, the Medicines and Healthcare products Regulatory Agency (MHRA)'s Yellow Card scheme recorded over one million reports of side effects—also known as adverse drug reactions (ADRs)—to medications. Previous studies have indicated that more than 99% of individuals have genetic variants which could lead to an adverse response to certain drugs.

In some cases, these reactions can be serious and lead to further health problems, longer hospital stays, or even death. The cost of ADRs to the NHS is estimated to be more than £2 billion a year.

The study, published in PLOS Medicine and led by Dr. Emma Magavern from Queen Mary University of London, analysed over 1.3 million ADR reports submitted to the MHRA Yellow Card scheme.