Two cannabis-based medicines have been recommended for use on the NHS for the first time.
Epidyolex has been approved for two rare types of epilepsy, Lennox-Gastaut and Dravet syndromes, and Sativex spray has been recommended for muscle spasms associated with multiple sclerosis (MS).
Charities welcomed the move, but said thousands of other people who could benefit from cannabis-based medicines had been left in limbo.
A change in the law in 2018 made it legal for doctors to prescribe medicinal cannabis, but many have been reluctant to do so, citing a lack of clear guidance on prescribing and funding issues.
This has led some families to go abroad in search of medicines, with some bringing them into the UK illegally.
The new guidance from the National Institute for Health and Care Excellence (Nice) looked at cannabis-based products for several conditions.
It found a lack of evidence for their use in the management of chronic pain and said people with the condition should not be prescribed drugs containing delta-9-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis.
It also said more research was needed on cannabis-based medicines to treat forms of epilepsy other than Lennox-Gastaut and Dravet. Between 8,000 and 9,000 people in the UK have Lennox-Gastaut or Dravet syndrome.
Millie Hinton, from the campaign group End Our Pain, said the guidelines were “a massive missed opportunity” to prescribe medical cannabis for thousands of people with a range of conditions.
Nice also recommended Sativex to treat muscle spasms in MS, a common symptom of the condition.
The families of two children, Billy Caldwell and Alfie Dingley, both of whom have severe epilepsy, have long campaigned for easier access to cannabis medicines in the UK.