Some drugs are completely ineffective or become deadly because of subtle differences in how our bodies function.
The British Pharmacological Society and the Royal College of Physicians say a genetic test can predict how well drugs work in your body.
The tests could be available on the NHS next year.
Your genetic code or DNA is an instruction manual for how your body operates. The field of matching drugs to your DNA is known as pharmacogenomics.
It would have helped Jane Burns, from Liverpool, who lost two-thirds of her skin when she reacted badly to a new epilepsy drug.
She was put on carbamazepine when she was 19. Two weeks later, she developed a rash and her parents took her to A&E when she had a raging fever and began hallucinating.
The skin damage started the next morning. Jane told the BBC: "I remember waking up and I was just covered in blisters, it was like something out of a horror film, it was like I'd been on fire."
Her epilepsy medicine caused Stevens-Johnson syndrome, which affects the skin and is far more likely to happen in people who are born with specific mutations in their genetic code.
Mrs. Burns says she was "extremely, extremely lucky" and said she supports pharmacogenomic tests.
"If it saves your life, then it's a fantastic thing." READ MORE...
