Halsey has opened up about how their multiple health issues have been "exacerbated" since she had her first child Ender.
The singer, 27, shared an update about her wellbeing to her Instagram stories after fans were concerned she wouldn't be able to perform her Love and Power tour later this month partly due to a video she'd posted.
"So I know a lot of you guys have been wondering what's going on with my health and some of you saw a TikTok that I posed yesterday, basically confirming that I'm allergic to like literally everything so I just wanted to give you a little update," they said in an Instagram story, while lying in bed with a heart monitor on, as reported by POPSUGAR.
Halsey has previously talked openly about having endometriosis – where tissue similar to the lining of the womb starts to grow in other places, such as the ovaries and fallopian tubes – and autoimmune issues – where the body's immune system attacks healthy parts of the body – throughout her life.
"Obviously, my health has changed a lot since I got pregnant and gave birth," she explained. "I started getting really, really, really sick and I've been kind of sick pretty much most of my adult life, but it started getting really bad."
They revealed they had recently been "hospitalised for anaphylaxis a few times", which led to her being officially diagnosed with a range of conditions, explaining her varying symptoms.
Anaphylaxis is a severe and potentially life-threatening reaction to a trigger such as an allergy, with symptoms including feeling light-headed or faint, breathing difficulties, wheezing, clammy skin, confusion and anxiety, collapsing or losing consciousness.
Their multiple diagnoses include Ehlers-Danlos syndromes (EDS), a group of rare inherited conditions that affect the connective tissue that provides support in different parts of the body; Sjögren's syndrome, which affects parts of the body that produce fluids; mast cell activation syndrome, where there is an increased risk of developing anaphylaxis along with having other varying symptoms; and postural orthostatic tachycardia syndrome (POTS), an abnormal increase in heart rate that occurs after sitting up or standing.
"I'm still looking for answers to the root cause of some of these things," they said.
"It could potentially be another type of autoimmune disease, and I've known about autoimmune issues for most of my life, especially having endometriosis but they've been exacerbated since I had Ender."
Halsey welcomed Ender in July last year.
As she hasn't toured in a while, she admitted she won't be able to in the same way she did when she was younger – "Where I basically didn't give a shit about my body and worked insane hours and days in a row."
But, after "learning a lot" about doing her job under the conditions she's experiencing, she wants to be honest with her fans, and still currently plans to go ahead with the tour in a way that benefits everyone.
"I'm on a treatment plan right now," they explained. "I'm in rehearsals for the tour. I'm really excited and really confident that I'm going to be able to do it in a way that's healthy, where I can perform my best for all of you.
"[The tour] is going to be delving into this weird, body horror about everything that I've been experiencing, feeling like my body is rebelling against me a little bit. And that started with being pregnant and my experience being pregnant, and now has evolved into something totally beyond pregnancy and postpartum.
"I have a lot of angst, I have a lot of energy, and I have a lot of confusion that I want to get out on that stage.
"Hopefully I've built a show that really reflects that and be a cathartic place for you to release some tension if you are feeling or have ever felt similarly."
Watch: Halsey has been 'in and out of hospital' for past few weeks