Aaron Carter has been warned he is too ''weak'' to fight off infection.

The 29-year-old singer was tested for HIV on 'The Doctors' and was relieved to learn he was did not have the virus, or other sexually-transmitted infections including chlamydia, syphilis and gonorrhea, but the TV medics had a stark warning for him.

After being given his results, Aaron said: ''Oh my God... Sorry, my heart is just, like ... you gotta understand out there. It's giving me anxiety. My heart is racing. I did not take any medications before I came here, actually in a couple of days, because I wanted to wean myself off of this.''

But Dr. Rodriguez warned: ''Listen up here, this is really important. You may be negative, but your system is so weak that it can't fight off a yeast infection.''

Dr. Travis Stork added: ''You've dodged some huge bullets, which is such a blessing.''

The 'Crazy Little Party Girl' hitmaker - who recently came out as bisexual - admitted taking the test was the ''scariest thing'' he'd ever done.

He said: ''That was the scariest thing I have ever done in my life. After not getting annual checkups and testing and being safe, actually, being safe so I could be safe for others, more importantly.

''That's what scared me. I felt like I was putting people at risk with my body... I didn't have the courage to go face the music.''

Aaron weighs just 115lbs and was told by the doctors he is ''malnourished'' and has a ''scary'' body mass index (BMI).

Dr. Stork warned: ''You are malnourished. And your body mass index at 17 is in a scary range. We can't just sit here and blame it on a hiatal hernia. We have got to work on this.''

Aaron had previously broken down in tears on the show and admitted he was ''concerned'' about his health as he discussed his addiction to cosmetic surgery and painkillers.

He said earlier this week: ''I'm concerned about my overall health because people tell me I look like I have AIDS or I look like I have cancer or I look like I'm dying.''

During the show, Aaron tested negative for both cocaine and meth, and the programme's doctor, Travis Stork, warned the star of the potential health consequences of taking drugs.

Turning to the troubled singer, Travis said: ''What scares me about that drug panel is that your sister [Leslie] perished from a drug overdose.

''You have a mixture of benzodiazepines with opiates, which is how many people accidentally can die. These medications - and I'm speaking now purely from the doctor's perspective - can be very, very scary.''

The 'Crazy Little Party Girl' hitmaker explained he takes the medications because he suffers from stress and anxiety, which are usually triggered by his fear of flying.

However, Aaron revealed he is actively seeking alternative ways to tackle his problems.

He shared: ''I don't want to be on that stuff. My sister passed away from it. It's not OK. I don't take it every day.

''To be honest with you, it's not going to be easy. I know that it's a hard road.''