Demi Lovato has celebrated her new lease on life by getting pierced.

The 21-year-old pop star has been open about her battle with drugs and alcohol and other self-harming tendencies.

But she couldn’t be happier after cleaning up her life, and told fans Saturday via Twitter she was celebrating her “2nd birthday” by getting a little body art.

“Today is my 2nd birthday. I'm 21 years old, but 2 years ago today, I finally started living.. I'm so beyond grateful..#ItWorksIfYouWorkIt,” Demi tweeted, referencing a common phrase from the Alcoholics Anonymous 12-step programme.

“Why not celebrate with some new piercings? 4 in one sitting.... #whoops!! #sorrynotsorry,” she revealed.

Demi shared a photo of her ear, which featured a few new holes, filled with new studs and rings.

The singer is currently on her Neon Lights tour and has been posting frequent updates for fans as she travels around the world.

“Okay, finally going to sleep. I'm SO HAPPY!!!!!!! Life is amazing.. You guys are amazing.. I've never been happier in my WHOLE life,” she tweeted after her show in Rosemont, Illinois on Friday night.

Demi’s successful comeback follows a tumultuous past.

The former Disney star checked into rehab in 2010 due to "physical and emotional issues".

She later admitted to suffering from bulimia and self-harming and confessed she had turned to drugs and alcohol during her darkest times.

The pop star said last March she had to overhaul her social circle to ensure she wouldn’t relapse and was stunned when she realised how her fame had affected her so negatively.

"A couple of months before I went to rehab, I had a birthday party and there were a couple of hundred people there. It was full of people who I considered my closest friends," she told Company magazine.

"When I turned my phone on after being in rehab for three months, I expected lots of text messages and phone calls. I had four texts. That was a wake-up call. I have severe trust issues but I try not to be jaded,” she said.

Demi is scheduled to continue touring the US and Canada until the end of the month, and will enjoy a few weeks off before she heads to South America. The tour will trek back to North America before wrapping in Monterrey, Mexico on May 17.