Two cannabis-based medicines, used to treat epilepsy and multiple sclerosis, have been approved for use by the NHS in England.
It follows new guidelines from the drugs advisory body NICE, which looked at products for several conditions.
Charities have welcomed the move, although some campaigners who have been fighting for access to the drugs have said it does not go far enough.
Both medicines were developed in the UK, where they are also grown.
Doctors will be able to prescribe Epidyolex, for children with two types of severe epilepsy – Lennox Gastaut syndrome and Dravet syndrome – which can cause multiple seizures a day.
Clinical trials have shown the oral solution, which contains cannabidiol (CBD), could reduce the number of seizures by up to 40% in some children.
Epidyolex was approved for use in Europe in September, but in draft guidance NICE initially said it was not value for money.
It costs between £5,000 and £10,000 per patient each year – but the manufacturer, GW Pharmaceuticals, has agreed a lower discounted price with the NHS.
It is estimated there are 3,000 people with Dravet and 5,000 with Lennox Gastaut syndrome in England.