Billy Caldwell is set to return home to Northern Ireland on Thursday despite the fact there is no approval from the Department of Health for his cannabis oil medication.
12-year-old Billy and his mum Charlotte have been in London following a fight to grant Billy access to the oil which is used to treat his severe epilsepsy.
Last month a 20-day emergency licence was granted for Billy after he was admitted to hospital in a critical condition having suffered multiple seizures.
After initially refusing, the Home Office rubber-stamped a special exemption licence to allow his mother to administer the THC-based cannabis oil required to keep his seizures under control.
The Northern Ireland Department of Health said it was working on a "timely solution" and had been in constant contact with the Home Office and advising Belfast Trust on the licence requirements and the best way to promptly complete this process.
On Wednesday Ms Caldwell said that the only thing stopping Billy returning home to Castlederg, Co Tyrone was ratification from the Department of Health.
Despite the lack of clarity around Billy's medication, the pair are set to fly into Belfast City Airport on Thursday afternoon with a press conference planned for the evening.
"While the Home Office in London and Charlotte's MP Orfhlaith Begley have done an amazing job in getting us this far, the Department of Health in Northern Ireland have not confirmed that Billy's medication will be available, whether for administration at a Belfast hospital, or to be taken home and administered in precisely the way he had previously been given his meds for nineteen months before the prescription ban," a family spokesman said.
"While we have been advised that the captain of our flight will be given secure custody of the original larger quantity of Bill's medicinal cannabis confiscated at Heathrow on June 11, we are also advised that the meds will be handed directly to the Department of Health in Belfast.
"We have also been told that the final four days' supply of Billy's meds, released under special licence by the Home Office on June 16, will not be released from Chelsea & Westminster hospital.
"This is a cause of concern, because after the administration of his Thursday morning dose of medicinal cannabis we do not know when the next dose will be released."