The Home Office has released the medicinal cannabis oil it confiscated from the mother of a severely epileptic boy, a family spokesman said.
Billy Caldwell, 12, and his mum Charlotte have been campaigning to get his life-saving medicine back, after it was seized at Heathrow airport on Monday.
Billy was admitted to Chelsea and Westminster Hospital in London on Friday after his life-threatening seizures intensified, with Charlotte stating that she would hold the Home Office and MP Nick Heard accountable if Billy dies.
Home Secretary Sajid Javid said: This morning, Ive used an exceptional power as Home Secretary to urgently issue a licence to allow Billy Caldwell to be treated with cannabis oil.
This is a very complex situation, but our immediate priority is making sure Billy receives the most effective treatment possible in a safe way.
We have been in close contact with Billys medical team overnight and my decision is based on the advice of senior clinicians who have made clear this is a medical emergency.
The Policing Minister met with the family on Monday and since then has been working to reach an urgent solution.
Speaking outside the hospital on Saturday, Charlotte said: Unfortunately, Billy had two more seizures overnight which has pushed him more into a crisis situation.
She added: The Home Office, myself and my team have been working extremely hard throughout the night to make this happen, which is truly amazing.
But there can only be one conclusion here: that my beautiful sweet little boy, who has a life-threatening form of epilepsy and one seizure can kill him, he needs his medicine back today.
On Friday night, the Home Office said it was in contact with Billys medical team and said they would carefully consider what options are available if they advise a particular type of treatment is urgently required.
Doctors said it was too dangerous to treat him with rescue meds at home and he can now be treated only with hospital-administered medicine.
Charlotte had a batch of medicinal cannabis oil taken from her at Heathrow Airport on Monday after a flight from Canada.
She said: Weve now reached the point where Billy is too ill to travel to get his medication, but his medication is stored minutes away from where were now living in London.
Despite the best and honest efforts of the NHS, frontline doctors are fighting Billys condition with both hands tied behind their back because the only medication that will be effective is the cannabis oil.
Charlotte credits the oil with keeping her sick sons seizures at bay, saying he was seizure-free for more than 300 days while on the medication.
She added doctors in Canada and Northern Ireland familiar with Billys case said the situation was life-threatening.
The child, from Castlederg in Co Tyrone, started the treatment in 2016 in the US, where medical marijuana is legal.
He became the first person in the UK to receive a prescription after his local GP in Northern Ireland, Brendan OHare, began writing scripts.
However, there is no record of a health service prescription being dispensed.
Dr OHare was summoned to a meeting with Home Office officials and told to stop.
Charlotte made the trip to Toronto and back with her sick son to get a six-month supply to treat up to 100 seizures a day, but said border officials seized the oil.