The 22-year-old picked up the injury in his side’s first win of the season last weekend, the 20-5 home triumph over Ospreys, and is due to see a specialist in London next week.
Although he missed out on the World Cup, Carter started in Wales’ win over the Barbarians earlier this month and was hoping to be in the running for selection for the Six Nations opener against Scotland at Principality Stadium on 3 February.
He joins another Wales lock, Christ Tshiunza, on the sidelines. He fractured his foot following his return from World Cup duty with Exeter Chiefs against Sale Sharks and is out until the New Year.
“It’s a severe hamstring tear and we are probably looking at three or four months,” explained Dragons head coach Dai Flanagan about Carter’s injury.
“He was jackaling and it’s a horrible mechanism for a tall man like Ben over the ball. The stretch of his hamstring was not nice to watch.
“He is meeting a specialist in London to see exactly what we need to do but it is a long-term injury. It’s a shame for Ben, he has got the work rate of two men, and it’s important that whoever replaces him brings the same work rate.
“E very team needs a Ben Carter, that second row who just keeps working and working so that other people can flourish. This is now an opportunity for Ben to have a rest, recover, and learn more about the game.”
Dragons are on safari in South Africa, taking in games against the Sharks in Durban on Saturday and then the Lions in Johannesburg next week. They were already without another Wales forwards, Taine Basham, who is serving a four match ban for a red card received against Leinster.
Flanagan hopes to have back row man Harri Keddie back in the mix in Durban as the Dragons seek to build on their morale boosting win over the Ospreys. He also hopes to get full back Jordan Williams back in action over the two games.