The 30-year-old One Direction star had recently been diagnosed with a "serious kidney infection" and had been told by doctors to rest and recover.
It is the latest in a series of health problems for the Stack It Up singer, who revealed in July 2023 that he was 100 days sober after spending time in rehab.
So what is wrong with the 1D hearthrob? Here is what we know.
Why is he in hospital?
Payne was on holiday in Lake Como, Italy, celebrating his one year anniversary with girlfriend Kate Cassidy when he fell ill, according to reports.
It is claimed he was admitted for treatment while doctors investigate further, and he has been told he will not be discharged for several days.
Why did he postpone his tour?
Payne announced in a video posted on Instagram in August that he was postponing his solo tour of South America after he had been in hospital with a "serious kidney infection". He said he was "sorry" but doctors had advised him to rest and recover and he did not feel able to do that while on the road.
The tour was scheduled to kick off on 1 September in Lima, Peru, with subsequent stops in Colombia, Chile, Brazil, Argentina and Mexico. The singer promised the shows are in the process of being rescheduled and that all tickets would be refunded.
New dates are yet to be confirmed but fans can sign up for notifications on his official website.
What other conditions has he been diagnosed with?
Payne - who is father to six-year-old son Bear with ex-partner Cheryl - confessed to fans in July that he was feeling “super low” and had been “diagnosed with a couple of conditions”.
Opening up about the health issues he was battling he confessed he experiences a lot of "manic things in my life".
The Strip That Down singer admitted that in contrast he also suffers "super lows" and he feared that during those moments he would lose his sobriety.
Read more here: Liam Payne says he feels 'super low' and that he's been 'diagnosed with a couple of conditions' (Yahoo Celebrity UK, 2 min read)
Why did he go to rehab?
Payne revealed in May 2023 that he had spent time in rehab and was more than 100 days sober.
Payne apologised after reflecting on what he had said, and it prompted him to check in to rehab and work towards sobriety.
Read more here: Liam Payne says he’s over 100 days sober: ‘I feel amazing’ (Independent, 3 min read)
How long has he struggled with his mental health?
Payne was just 14 when he first auditioned for The X Factor in 2008. He did not make it past Boot Camp but returned to the talent show in 2010 and became part of globally successful boyband One Direction.
But the pressures of international fame and constantly being on the road with the band from such a young age took its toll on Payne.
In 2021 he opened up about his struggles with addiction and depression during his time in 1D. Payne admitted he became reliant on alcohol and experienced suicidal thoughts.
Read more here: Liam Payne says he struggled with 'severe' suicidal ideation and addiction when he was in One Direction (INSIDER, 4 min read)
For confidential emotional support at times of distress, contact The Samaritans at any time by calling 116 123 or emailing email@example.com.
Watch: Liam Payne hospitalised with serious kidney infection