Media playback is unsupported on your device Media caption Bailey Williams can have multiple seizures every day

An epileptic teenager's family are paying thousands of pounds a month for privately prescribed medical cannabis because they cannot get it on the NHS.

The law changed last November so specialist doctors could offer cannabis-based medication.

But there have only been a handful of prescriptions because of concerns about safety and effectiveness.

Bailey Williams' parents, from Cardiff, said he has had fewer seizures since he has started taking the drugs.

But they said his next monthly batch is set to cost £4,000 and they are worried they will not be able to afford it long-term.

The 17-year-old's mum, Rachel Rankmore, said: "The last few months, he has started to speak, interact in conversation, play with his toys.

"He has a reduction in seizures, so he has a better quality of life.

"We'd got nothing left to lose, we just needed to try it."

Bailey has a rare form of epilepsy called Lennox-Gastaut Syndrome and he can have multiple seizures every day.

The cannabis oil he has been prescribed by a private paediatric neurologist in London is called Bedrolite.

That contains CBD and a small amount of THC - the psychoactive compound of cannabis.

Image copyright Family photo Image caption Craig Williams and Rachel Rankmore want Bailey (second right) to be able to enjoy his life with brother Ross

Bailey's private prescription, which he was given in June, is specially imported from the Netherlands.

His father, Craig Williams, said: "If you were to purchase it direct from Holland, it's £150 per bottle.

"Because the UK have got to import it, you've got your importation fees, you've then got your pharmacy costs on top, so that same £150 bottle becomes £500, which Bailey needs every two-and-a-half to three days".

The family expect Bailey's October prescription to cost almost £4,000 as the dose has increased.

The law on medicinal cannabis

Until last year, medical cannabis with THC was illegal in the UK.

On 1 November, all cannabis medicines were moved from Schedule 1 of the Misuse of Drugs Regulations to Schedule 2, to recognise there is evidence of benefit for some.

This month, the body that advises on best treatments, the National Institute for Health and Care Excellence (NICE) chose not to recommend the wider use of medical cannabis, because of a lack of clinical evidence. It is consulting on those findings and will publish final guidance in the autumn.

An NHS England review said the health service must support studies to gather evidence "as soon as possible".

The National Institute for Health Research is inviting bids for funding to carry out research into the medicinal uses of cannabis.

It means many people are turning to private clinics for medical cannabis.

The family has raised about £15,000 to fund the drugs.

Bailey's mum said they could not "keep effectively begging for money".

Cardiff and Vale health board said it acted in "the best interests" of patients and put them at the centre of "everything".

Image copyright Family picture Image caption Fundraisers at the top of Pen y Fan in the Brecon Beacons after a sunset to sunrise cycle

A spokesman said: "We have discussed the concerns the family have raised about the management of his condition.

"We will continue to work with the family."

The Welsh Government said no cannabis products had passed tests of the Medicines and Healthcare products Regulatory Agency.

A spokesman said: "Cannabis products may therefore pose unquantified and potentially greater risks to patients than licensed medicines."

Image copyright Family photo Image caption Prizes at a charity auction in June to raise money for Bailey

The Department of Health and Social Care said there was "a clear consensus on the need for more clinical evidence."

It said the decision to prescribe "must remain a clinical one, made with patients and their families".

A spokesman said: "We will now carefully consider the NHS's findings, alongside the recently published Health and Social Care Committee report, to identify how we can better support clinicians in prescribing cannabis-based medicinal products where clinically appropriate."