5 Seconds of Summer drummer, Ashton Irwin, underwent surgery for appendicitis, the band's website has confirmed in a note.

"Hi guys, we have some news for you today. Ashton has come down with a case of appendicitis and had to have an operation.

"He's doing great and will be back up & running in no time, but he'll need to rest up for the next week or so...

"Unfortunately this means that we'll no longer be able to fly back to the UK this weekend for the BBC Radio 1 Teen Awards. We will also be postponing next week's trip to Japan (more info to come soon).

"We are so sorry to everyone that had planned on seeing us. We were so excited to come see you all and we never want to make any of you sad... We hope you understand!

"Thanks so much for supporting all we do, we love you. Can't wait for us four lads to get back on the road (minus one band appendix) and rock out with you all again soon!"

Ashton himself tweeted about his unexpected trip to the hospital:

"Sup guys! I'm so sorry too anyone I've let down, I promise we will make it up too ya! I'll be better soon, thanks for all the love xx"

According to Medical News Today, appendicitis is "a condition in which the appendix becomes swollen, inflamed, and filled with pus." In most cases, an appendectomy, a surgical procedure which removes the infected appendix, is called for.

In some cases, persons with appendicitis are advised to take antibiotics for several days first, before the surgery is performed, noted Medical News Today. The delay is reportedly "to shrink the appendix and clear up surrounding infection."

It isn't clear if Ashton now doesn't have an appendix but what's clear is that 5SoS fans are sad upon learning of the news. Fans of the band expressed their heartbreak and well wishes on Twitter, which means #getwellsoonashton is trending. Some of the tweets are below.

"#getwellsoonashton you're always here for us now it's our turn to be here for you. we love you ash :) have a speedy recovery x", reads one tweet.

"ill donate my appendix for u #getwellsoonashton", said another.

"ash, don't be sorry - it's not your fault, please don't blame yourself. we love you so much xx #getwellsoonashton", tweeted one fan.

"#getwellsoonashton Even though he's probably in pain and he won't show it, I hope he gets better really so... https://vine.co/v/OqpT2phAz9F ," said @irwinning_xo.

"it hurts my heart that this little ball of sunshine is in so much pain #GetWellSoonAshton #AshtonGetWellSoonWeLoveYou", reads one sweet message.