The change is a victory for Charlotte Caldwell, 52, whose son Billy, 14, has epilepsyCHARLES MCQUILLAN/GETTY IMAGES

Medicines derived from the cannabis plant have been approved for use on the NHS for the first time.

The National Institute for Health and Care Excellence (Nice) has approved a drug for epilepsy in children and another for multiple sclerosis. Campaigners hope they open the door for more cannabis-based drugs.

Epidyolex, made from cannabis oil, can reduce seizures in children over two with two rare forms epilepsy. Sativex is a spray containing cannabidiol (CBD) and tetrahydrocannabinol (THC), the psychoactive constituent of cannabis, and can treat muscle stiffness in people with multiple sclerosis.

In draft guidance in August Nice said the drugs were too expensive for NHS use, but the regulator has since recommended both medicines. Both are made by GW Pharmaceuticals, whose chief operating officer,…