Avril Lavigne was ''in bed for f***ing two years'' whilst fighting Lyme disease.

The 'Complicated' hitmaker has been struggling with the debilitating condition since she began feeling the symptoms during her 2014 tour, and says the disease left her bedridden for two years, because it went ''undiagnosed for so long''.

Speaking to Billboard magazine, she said: ''I was in bed for f***ing two years. It's a bug - a spirochete - so you take these antibiotics, and they start killing it. But it's a smart bug: It morphs into a cystic form, so you have to take other antibiotics at the same time. It went undiagnosed for so long that I was kind of f***ed.''

Avril, 34, revealed she first went to doctors about her health when she was left feeling ''achy and fatigued'', but multiple health care professionals were unable to find a cure after having misdiagnosed her.

She says a friend then told her she could have Lyme disease, which prompted her to put a phone call in to former 'Real Housewives of Beverly Hills' star Yolanda Hadid - who has been open about her own battle with the disease, which her daughter Bella Hadid also has - who gave her the number for a specialist to help her get treated.

Previously, Avril claimed she had ''accepted death'' when she was bedridden with the disease, and her new single 'Head Above Water' - which was released last month - was written during that time.

She wrote in a note on her website: ''I spent the last few years at home sick fighting Lyme Disease. Those were the worst years of my life as I went through both physical and emotional battles...

''Thank you for waiting so patiently as I fought through and still continue to fight, the battle of my lifetime. The first song I am choosing to release is called 'Head Above Water'.

''It is also the first song I wrote from my bed during one of the scariest moments of my life. I had accepted death and could feel my body shutting down. I felt like I was drowning. Like I was going under water and I just needed to come up for air. Like I was in a river being pulled in a current. Unable to breathe.''