Heavy metal star Ozzy Osbourne has been ordered to go back on tour by his sick wife after he nearly passed out watching her undergo chemotherapy.

He had originally taken the decision to cancel his appearances on the Ozzfest tour so he could be at his wife's side as she battles cancer of the colon.

But after he went with her to her first session of chemotherapy she realised he would be better off performing.

"After attending his wife Sharon's first chemotherapy treatment, he nearly passed out and had to be taken to a recovery room," said their publicist.

"Sharon now realizes that Ozzy is better off on the road so she's shipped him back out to finish Ozzfest."

Ozzy has seen a resurgence in his career since the TV show

The 57-year-old former Black Sabbath frontman had already broken the news to his fans that he would be taking a three-week sabbatical from the tour.

Now he will miss just two US dates in Ohio and will rejoin the tour in Michigan on 7 August.

Sharon, who has managed Ozzy for 20 years, organises the annual shows, which feature hard rock acts and is headlined by her husband.

She was diagnosed with cancer of the colon in July and immediately underwent an operation.

But further tests revealed the cancer had spread and she has now begun a three-month course of chemotherapy.

Shaved head

Her treatment is likely to be documented in the second series of the highly successful reality TV show The Osbournes.

When Ozzy first learned his wife was ill he became so hysterical he had to be sedated by doctors.

But he has promised that if his wife loses her hair he will shave off his own famously long mane.

The MTV show sees Ozzy, Sharon and their children Kelly and Jack, go about their unconventional family life in their Beverly Hills mansion.

Eldest daughter Aimee, refused from the outset to be part of the show and moved out of the family home during filming.

Teenagers Kelly and Jack have become overnight stars due to the success of the first series.

Kelly has recorded a cover version of Madonna's hit Papa Don't Preach and has landed a role in the remake of the movie Freaky Friday.

Jack is often pictured hanging out with models and musicians.