Avril Lavigne supported Justin Bieber through his battle with Lyme disease.

The 35-year-old singer revealed in 2015 she had been struck down by the debilitating tick-born illness, so when the 'Believe' hitmaker revealed in January he had also been suffering with the condition, she reached out to offer him help and advice.

She told 'Entertainment Tonight': ''I just reached out like, 'Yo, here for you if you need any advice. I can share my knowledge with you.'

''He was appreciative of that, but I think it seems like he is doing well. He put out new music and he had a tour, also.

''He is also a warrior overcoming Lyme and that was the whole inspiration behind my song, 'Warrior'.

'''Warrior' and 'Head Above Water' were the two first songs I wrote for this album because I was freshly coming out of fighting Lyme disease, so naturally that was what was on my heart.''

The 'Skater Boi' hitmaker was warned she is at a higher risk of contracting coronavirus due to having Lyme disease, so hasn't left her house for six weeks and is doing her best to minimise risks, including not inviting anyone new into her home, cleaning any packages she receives, and to pass the time she's been binge-watching ''awesome'' 'Schitt's Creek' and doing a lot of cleaning, which she joked doubled as her exercise.

She said: ''I embrace it because I break a sweat and it's good cardio, so I'm working out and getting the floors done!

''I've just been trying to eat really healthy, sleep well, get some sunshine, stay in good spirits.''

Avril has also been writing new music with a ''rock-and-roll, country flair''.

She added: ''And, naturally because I'm just sitting in a house, I'm writing songs.''

The 'Warrior' singer has abandoned cooking regular meals in favour of producing ''one huge buffet'' for her household to graze on.

She said: ''I'm also finding it's been a lot of work cooking all day, so I've just started to make one huge buffet -- a few vegetables, big salad, couple of proteins, couple of healthy carbs -- and just started having a huge buffet to eat all day to feed the household. I don't normally burn food but I burnt beans!''