Barnes picked up the problem inside the opening 12 minutes of the Magpies' thumping 8-0 victory over Sheffield United in the Premier League last Sunday.
Howe revealed on Tuesday that the club feared the winger would be facing «months rather than weeks» out and may require surgery.
It has now been confirmed that Barnes will indeed miss the next three months with an injury underneath his toe, but an operation is not required.
Speaking about Barnes at a press conference on Friday ahead of Saturday's Premier League clash with Burnley, Howe said: «We think he's going to be out for around three months. No surgery required, which is good news, but his foot is now in a boot.
»It is an injury underneath his toe and he's now started his recovery. I think he's going to be quite sedate for a period of time because he's got to rest the toe, he's got to give it every chance to recover and then we'll have to build him up slowly, so that's why it's the three months."
Howe added: «It's come at a shocking time for Harvey. He was beginning to find his rhythm. With so many games coming up, it's a huge blow to lose any player.
»We have to deal with it, accept it and we wish him a speedy recovery."
Barnes was one of Newcastle's marquee signings in the summer transfer window, joining from boyhood club Leicester City for around £39m.
The one-cap England international scored and provided an assist as a substitute on his Magpies debut in a 5-1 home victory over Aston Villa at the beginning of August.
Barnes has played in each of Newcastle's first seven games in all competitions, but predominantly featured as an
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