Dermot Devlin campaigned to get Vimizim approved in the UK after suffering from a rare degenerative disease.
The government legalised the drug on Monday and Dermot had his first treatment on Tuesday.
The birth defect, called Morquio, means his body is around 3 foot tall, which cramps the organs.
One major organ affected is the lungs - which resulted in Dermot collapsing on a plane.
He hopes this new treatment will give him back his independence.
Dermot has also called for the Irish government to follow in the UKs footstep.
Government announces Stormont Brake will not be pulled over change of EU law
A man assaulted with hammer during robbery in South Belfast
Finance Minister makes 20-month Civil Service pay offer
Firefighters tackle large fire at Coleraine recycling plant
Institutional abuse survivors urged to come forward before deadline passes