Published Thursday, 07 October 2010
Harrison was examined by team doctors before travelling to Delhi and was initially advised that a recovery may be possible.
He participated in the 200m Freestyle on Tuesday morning.
But after two days of resting and a further consultation with the medical staff, it was advised that he would not take part in any further competition.
Ryan said: "I'm obviously devastated that my first Commonwealth Games has come to an end. It means a lot to me to represent Northern Ireland as you don't get that opportunity too often.
"Coming into these Games I was looking good to make a final in the 200m Freestyle and clearly my body told me otherwise. However I'm going to take as much positivity from this as I can".
Robert McVeigh from the Northern Ireland Commonwealth Games Association said: "It is unfortunate that one of Northern Ireland's best competitors has had to withdraw from competition. The team is united in wishing Ryan a speedy recovery".