Barnes picked up the injury in the 8-0 demolition of Sheffield United in the Premier League on Sunday.
It was just his second start for the Magpies since switching from Leicester City for £38m in the summer but Barnes lasted a little over ten minutes before going off injured to be replaced by Anthony Gordon.
Newcastle United were anticipating a few weeks out for Barnes but he could be missing for a significant period of time.
Asked if Barnes could be out for some time, Howe said: “Yes, we’re fearing it’s going to be. It’s difficult. I don’t want to put a time on it until we get confirmation from the specialist, but I think it will be months rather than weeks.”
“It’s an injury to a part of the foot just below the toe. I think it’s quite a substantial injury. We’ve had it scanned, we’re waiting now for a specialist’s opinion on what to do next, whether there’s surgery involved or not. I don’t think it was a tackle, I think it was just pushing off to run, a very unusual injury. I won’t go too technical because I’m not medically qualified to do so, but yes, very unusual.”
“He was down after the game because he knew it wasn’t a normal injury where you feel a muscle and think that might be one or two weeks.
“This was a slightly more complex issue, and I think he probably feared the worst because there was no one around him and he knew it wasn’t quite right. There’s no doubt he’ll be disappointed because he was very keen to show his value and worth and Sunday was an opportunity to do that. But whatever the injury is, we’ll support him and we know he’s a top quality player and he still has a massive part to play.”
Newcastle will face Manchester City in the Carabao Cup on Wednesday.