The family of a six-year-old girl are trying to raise £15,000 for a cannabis-based treatment after she was diagnosed with a rare form of epilepsy.
Sienna Richardson was found to have Landau Kleffner syndrome after showing problems with her communication skills.
Her family, from Telford, believe medicinal cannabis oil Bedrolite offers the best outcome, but have been told it is not available to Sienna on the NHS.
They hope to raise enough for 12 months worth of treatment in the Netherlands.
Sienna's mother, Lucy, said her daughter, who had previously "excelled" at school, stopped responding to instructions or her name last summer, and initially they thought there may be problems with her hearing.
Hearing tests and an MRI showed no problems but the family was sure something was wrong.
An electroencephalogram (EEG) test initially diagnosed her with focal epilepsy, but when the treatment made her worse, the "heartbreaking" new diagnosis was made and Sienna was sent to Alder Hey Children's Hospital in Merseyside.
Steroid treatments have not been successful, and while surgery would be an option, it could leave Sienna with paralysis of her left side.
If untreated, she could have permanent speech and language difficulties.
Through research, the family found out about Bedrolite, a medical cannabis oil made by Bedrocan, which is the sole supplier of medicinal cannabis to the Dutch government's Office for Medicinal Cannabis.
On 1 November 2018, cannabis medicines were moved in the UK from Schedule 1 of the Misuse of Drugs Regulations, meaning they have no therapeutic value, to Schedule 2, to recognise there was conclusive evidence of benefit for some patients.
From that date, specialist doctors were allowed to prescribe cannabis medicines "where there is an unmet clinical need".
But despite the law change, some families have been unable to get a prescription on the NHS.
And although it has been prescribed privately to some at Portland Hospital in London, the family said they were told there was no space for Sienna to be treated there.
Within 24 hours of launching their appeal, Sienna's family had raised more than £2,000 towards taking her to the Netherlands for treatment.
"We're overwhelmed with support we have had, not just for the fundraising, but over the last six months," Mrs Richardson said.
"We were anxious about putting it out there but it is support we need at moment.... we have got to do it for Sienna."
An NHS spokesperson said: "The decision to prescribe medicinal cannabis is ultimately a clinical decision for specialist hospital doctors, made with patients and their families."
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