Niall Horan thinks he has pneumonia.

Niall Horan

Niall Horan

The One Direction heartthrob was struck down with a nasty chest infection earlier this week but it looks like his condition has deteriorated and he'll probably be forced to spend the festive season in bed as he thinks he's now developed the lung inflammatory condition.

Taking to Twitter on Thursday (22.12.16), he said: "Should have listened to my mother years ago when she said, 'Don't go out with wet hair or you'll get pneumonia.' "

The 23-year-old singer was first ordered to bed on Monday (19.12.16) and was devastated that his ill health had destroyed his plans leading up to Christmas Day (25.12.16).

He said: "Get a chest infection Christmas week .... cool cool cool ........ not ideal (sic)"

But the pop isn't the only member of 1D - who are currently on hiatus - to come down with an illness recently, as his fellow bandmate Liam Payne is also suffering with a medical ailment and is unable to get into the studio to work on his new solo songs.

During a Q&A session called '#AskLiam' on Twitter, one fan asked the hunk: "@LiamPayne how are you today? #askliam (sic)"

To which the 23-year-old singer replied: "@1DGlobalPH I am at home and am sick so I can't record at the moment (sic)"

But, although he's bedridden, Niall's chest infection won't hinder his solo music career, as he recently said he would be taking a few months off to be with his family and friends before he gets back into the "writing zone" in February.

He said: "I'm gonna head home and chill out as it has been hectic the last few months. Looking forward to getting home at Christmas. I haven't been home since last Christmas so I miss everyone and hopefully this year I'll get to spend some quality time with family and friends.

"I really do wish I could spend more time at home but with Ireland as small as it is, I sometimes struggle to relax so fingers crossed because I miss that place a lot. After Christmas, I'm gonna fall off the face of the earth and do one of my disappearing acts. I want to come up with more song ideas and get back in the writing zone. So have a lovely Christmas and happy New Year and I'll see ya in Feb. (sic)"

Pneumonia is a bacterial infection that causes swelling of the tissue in the lungs. The symptoms can develop within 24 to 48 hours and typically include a dry cough, difficulty breathing, a rapid heartbeat and fever. Doctors usually prescribe antibiotics.