In a video displaying his symptoms, the Canadian singer said they were "pretty serious".
Justin Bieber has shared a video in which he opens up about why he recently cancelled concerts this week.
The 28-year-old posted on Instagram to tell fans that he has been diagnosed with Ramsay Hunt Syndrome, a condition that has left half of his face paralysed.
"As you can see this eye is not blinking. I can't smile on this side of my face. This nostril will not move," the 'Honest' singer said in the clip.
"So, there's full paralysis on this side of my face."
Ramsay Hunt Syndrome is when a shingles outbreak has an impact on the facial nerve near someone's ears and can cause facial paralysis.
According to
the Mayo Clinic, prompt treatment of Ramsay Hunt syndrome can reduce the risk of complications, which can include permanent facial muscle weakness.
For most people, the facial paralysis associated with the syndrome is temporary.
"It is from this virus that attacks the nerve in my ear and my facial nerves and has caused my face to have paralysis," Bieber added, showing how the right side of his face had been affected.
Asking fans to be patient as he gets back on his feet, he cancelled three shows last week due to doctor's orders, saying he was "physically, obviously, not capable of doing them."
"This is pretty serious, as you can see. I wish this wasn't the case, but, obviously, my body's telling me I've got to slow down," Bieber said.
"I hope you guys understand. I'll be using this time to just rest and relax and get back to 100% so that I can do what I was born to do."
The Canadian performer also told fans that he has been doing facial exercises to help "get back to normal" but is unsure of how long that could take.
