Gwen Stefani "almost throws up in her mouth" singing old No Doubt songs.

The 54-year-old star is set to reunite with her group at Coachella in April - which will mark her first performance with the 'Just A Girl' ska punk hitmakers since 2015 - but she's nervous about delving into their classic back catalogue.

As quoted by the Daily Star newspaper's Wired column, she said: "I can't listen to a lot of songs because they speak so clearly to me.

"You have regrets, you make mistakes, and a lot of songs are about that.

"When I do 'Ex-Girlfriend', when I say it I almost throw up in my mouth because I just know exactly where I was at the moment to write that song. It brings you right back."

In the first verse, she sings: "I kinda always knew I'd end up your ex-girlfriend, I hope I hold a special place with the rest of them.

"And you know it makes me sick to be on that list, but I should have thought of that before we kissed."

Gwen is excited to be back on stage with her bandmates, and despite any nerves about the performance, she knows it will be "like riding a bike".

Speaking on 'Jimmy Kimmel Live' last week, she said: “It’s going to be amazing. I’m so excited and I think what is going to be hilarious is I know what’s going to happen.

“I’m going to get on stage and look around and just start cracking up. It’s just going to be like riding a bike.

"We’re going to be like, ‘What are we doing? We’re in the future right now.’ ”

However, there could be an issue with the lyrics as Gwen - who accidentally revealed 'Different People', from 1995 album 'Tragic Kingdom' will be on the setlist - admitted she doesn't recall all the words.

She confessed: “I don’t remember them, no. Not at all. I think I’m going to have to learn like eight or nine.”