Halsey has confirmed they have lupus and a "rare T-cell lymphoproliferative disorder."
The singer had hinted at a diagnosis in a social media post earlier this week, but has now confirmed the illness.
"In 2022, I was first diagnosed with Lupus SLE (systemic lupus erythematosus, the more technical name for lupus) and then a rare T-cell lymphoproliferative disorder," she wrote on Instagram. "Both of which are currently being managed or in remission; and both of which I will likely have for the duration of my life. After a rocky start, I slowly got everything under control with the help of amazing doctors. After 2 years, I'm feeling better and I'm more grateful than ever to have music to turn to."
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease which can cause pain and swelling in the joints, rashes and fatigue.
Lymphoproliferative disorders cause an uncontrolled production of lymphocytes, a type of white blood cell.
The 29-year-old Grammy nominee had previously said they were "lucky to be alive" due to her ongoing health issues.
The Without Me singer, who has just released single The End from her fifth studio album, is mum to three-year-old son, Ender.