The family of a Sydney teenager who is suspected of shooting himself in the head in a game of Russian roulette learnt of the distressing news when his friends began posting about it on social media.

Josh Taylor, 19, remains in a critical but stable condition in Westmead Hospital after he suffered a single bullet wound to the side of his head in Pitt Town, in Sydney's north-west, about 6.30pm on Friday.

Josh Taylor was airlifted to hospital after the incident. Credit:Facebook

Mr Taylor was sitting in a car outside the IGA supermarket on Eldon Street with three friends, who told police he took a gun, held it to his head and fired while playing the deadly game of chance.

The only bullet in the gun discharged and entered his head, several centimetres above his ear.