Cannabis should not be prescribed for chronic pain, the NHS funding watchdog has ruled, in a decision branded ‘devastating’ by campaigners.

New guidance, released this week by the National Institute for Health and Care Excellence (Nice), says there is no evidence to show that cannabis is beneficial for people suffering long-term pain.

Charities had hoped that the drug would become widely available after it was decriminalised for medical use by Sajid Javid last November following high-profile campaigns involving children such as Alfie Dingley and Billy Caldwell, who both have hard-to-treat epilepsy.

But under the new ruling only people with two rare types of epilepsy, Lennox-Gastaut and Dravet syndrome, will be able to access the cannabis-derived drug Epidyolex through the NHS, meaning both Billy and Alfie will miss out.

Without Nice approval only a tiny handful of doctors are qualified and willing to prescribe medical cannabis, meaning they are virtually impossible to obtain in practice.

Millie Hinton, from the campaign End Our Pain, said the guidelines were ‘a massive missed opportunity’ for thousands of people with a range of conditions.

“It is particularly devastating that there is no positive recommendation that the NHS should allow prescribing of whole plant medical cannabis containing both CBD (cannabidiol) and THC in appropriate cases of intractable childhood epilepsy,” she said.

“It is this kind of whole plant extract that has been shown to be life-transforming for a significant number of children, including those involved in the high-profile cases of last year which led to medical cannabis being legalised.”

But families of children with epilepsy are paying thousands of pounds every month on private prescriptions for medical cannabis and say the youngsters show dramatic reductions in seizure rates.

Charities warned that Nice was too focussed on evidence from randomised control trials, while ignoring the everyday evidence from people taking the drugs.

Simon Wigglesworth, deputy chief executive at Epilepsy Action, welcomed the decision to recommend Epidyolex, however, he said there were many thousands of people with other complex and treatment-resistant epilepsies who could potentially benefit from cannabis-based medicines.

Only around 8,0000 to 9,000 people in the UK suffer Lennox-Gastaut and Dravet syndromes compared with the 500,000 people who suffer from all forms of epilepsy.

However Nice did recommend the cannabis-dervied nasal spray Sativex for muscle spasms in multiple sclerosis (MS).

And in August the body also approve Nabilone, a synthetic cannabis-based medicine for cancer patients struggling with side-effects of chemotherapy.

Genevieve Edwards, director of external affairs at the MS Society said evidence shows cannabis-based treatments could help around 10,000 people with MS get relief from pain and spasms when other treatments have not worked.