Andrea Davies believes oil derived from the drug could alleviate symptoms of her son Adrian Freeman's severe epilepsy.
Adrian, 34, has learning difficulties and has suffered serious head injuries as a result of his epileptic fits, which Ms Davies says happen on a daily basis.
The case is the latest in the debate about the benefits of cannabis oil as a treatment for people with conditions ranging from epilepsy to multiple sclerosis and pancreatic cancer.
Ms Davies, of Longden, near Shrewsbury, said: “Adrian has basically never had a day without any epileptic activity. He has had many, many traumatic injuries and has had to go into the intensive care unit before.
“When he has a fit he is thrown head first directly into whatever happens to be in front of him. It can happen at any time and has been quite badly hurt.”
Shrewsbury MP Daniel Kawczynski has given his support to Ms Davies and called for a review of his treatment.
Cannabidiol or CBD is one of the components of cannabis, and studies have shown that it can reduce the frequency of seizures in people with epilepsy. Sativex is one CBD-based product that was recently listed by the Home Office as authorised to be given under prescription after a national campaign.
Home Secretary Sajid Javid announced this year that cannabis-based medical treatment should be placed in schedule 2 of the 2001 Misuse of Drugs Regulations, allowing clinicians to prescribe them by the autumn. In the meantime, clinicians can still put in applications for cannabis-based medicines to the expert panel that was set up in June.
Ms Davies, 60, said Adrian’s doctors at the Royal Shrewsbury Hospital are not properly considering cannabis oil as a treatment for Adrian’s symptoms, and that instead they suggest two forms of surgery.
She said: “I raise the idea of using cannabis oil to treat him with the healthcare professionals but they just dismiss it out of hand. It is very frustrating and quite demoralising. They just say they can’t do it here, there’s no chance.
“I feel that it would be much less drastic than the kind of invasive surgery they are talking about, which is quite experimental and far from risk free. Especially with Adrian, he just wouldn’t know what was happening to him.”
Royal Shrewsbury Hospital declined to comment on its care of Adrian.
What did Daniel Kawczynski say?
Mr Kawczynski has written to Ms Davies offering his support and reassuring her the issue of cannabis oil was a high priority for ministers.
He told her: “It is only right that people with conditions like multiple sclerosis and severe epilepsy are able to gain access to appropriate treatments, and I hope I can assure you that the government and health service are making every effort to ensure this is the case.
“Regarding Sativex, I know that it is licensed for certain uses in the UK, as it has recognised benefits for sufferers of multiple sclerosis. However, the guidance from the National Institute for Health and Care Excellence (Nice) states that it is not a cost-effective treatment for the NHS to routinely offer. I know that Nice update their guidance regularly, and it will be for them to discuss with the manufacturers of Sativex to find a model of funding appropriate to the NHS.
“I am sure you are aware that recently the Home Secretary announced a review of the use of medicinal cannabis products. I hope you welcome the fact that all applications for medicinal cannabis products like cannabis oil will be carefully reviewed by an expert, medical panel, to ensure that every patient receives authoritative, clinical advice on their condition.
"The panel will take into account the urgency of every case, and will make sure that it recommends a safe and effective approach to treatment. I believe this represents a sensible and compassionate approach to the use of cannabis for medicinal purposes.”