Hundreds of children with severe epilepsy will be able to access a cannabis-based treatment on the NHS early in the new year.
NHS England said access to Epidyolex, a cannabidiol (CBD) oral solution, has been fast-tracked to be available from January 6.
The cannabis-based medicine was recommended for use on the NHS to treat two rare types of epilepsy, Lennox-Gastaut and Dravet syndromes, for the first time in November.
It will be available for children from the age of two and adults in combination with clobazam, and NHS England estimates around 2,000 people could benefit.
Clinical trials have shown the treatment could reduce the number of seizures by up to 40% in some children.
Campaign group End Our Pain called the move a step in the right direction, but said for people in need of products containing both CBD and Tetrahydrocannabinol (THC) it was "another false dawn and missed opportunity".
A change in the law in 2018 made it legal for doctors to prescribe medicinal cannabis.
However, many doctors have been reluctant to do so, citing a lack of clear guidance on prescribing and issues over funding for the drugs.
This has led some families to go abroad in search of medicines, with some bringing them into the UK illegally.
Millie Hinton, director of End Our Pain, said the announcement would bring joy to some families but would prolong the suffering of people who need access to products containing CBD and THC.
Some families are paying around GBP2,000 ($A3800) a month privately for these products, she added.
She said: "They have been pushed to financial breaking point funding the only medicine that gives their children significant seizure control and the quality of life they deserve. Some have actually felt forced to sell their family homes.
"So, whilst fast-tracking access to a CBD-only product is a step in the right direction for some desperate families, for those that need the products containing both CBD and THC it's another false dawn and missed opportunity.
"These families need immediate action to secure NHS prescriptions for the CBD and THC whole plant medical cannabis products.
"It is unbelievably cruel to leave these vulnerable families in such a desperate state. All these families want for Christmas is for the Government to honour the promises they made to them."
A review earlier this year looked at the barriers to prescribing cannabis-based medicinal products where it is safe and clinically appropriate.
The National Medical Director and Chief Pharmaceutical Officer for England will write shortly to NHS doctors and pharmacists to clarify the procedure for prescribing unlicensed cannabis-based products where there is an unmet need and it is clinically appropriate.
Around 8,0000 to 9,000 people in the UK suffer Lennox-Gastaut and Dravet syndromes.
Australian Associated Press