The Boys Star Erin Moriarty Reveals the Autoimmune Battle Behind Her On-Set Struggles

Here’s a slice of what really goes on behind the scenes on The Boys—and nope, it’s not all capes and snark. Erin Moriarty, who plays Annie/Starlight, just opened up about the absolute toughest patch of her time on the show, and it’s one of those stories that makes you rethink everything you’re seeing on screen.

Filming Through the Pain (That We Never Saw)

So, the fourth episode of season five, 'King of Hell,' is apparently one of the biggest for Annie, at least emotionally. But for Moriarty, it was also a personal hell—literally. Turns out she shot this major episode in the middle of what she now knows was a full-blown autoimmune health crisis, long before she figured out what was actually happening to her body.

She dropped all this recently on Instagram, with a pretty graphic knee photo for emphasis. Here’s what she wrote, and yes, she gets blunt about it:

'Not long after this episode, I started to lose the ability to walk. The numbness in my feet led to a lot of falling. The night before we shot my segment of this episode, I fell and shredded up my knee.'

'This isn't a pity post. It's mostly to say: fuck autoimmune disease. Fuck it so hard. Fuck the ignorance surrounding it, too.'

So when you see her giving it everything as Annie, just know she was barely holding herself together off-camera. (Try saying superheroes are 'just acting' after this, I dare you.)

What Was Actually Going On: Moriarty’s Health Battle

If you missed the earlier posts, Erin’s been public about her diagnosis: Graves' disease, which is an autoimmune condition that targets the thyroid. (Symptoms: tremors, dropping weight, weird eye stuff—the works.) She only got diagnosed after things got so bad she could no longer ignore what was happening.

• She started noticing symptoms well before episode 4, but chalked it up to normal exhaustion and stress (because, you know, starring in a giant TV show isn’t stressful at all...)
• At the worst point, she was having trouble walking and kept falling, but still pushed through the shooting schedule
• Right after this episode, she finally found out she had Graves' disease and started treatment—which, according to her, gave her relief within a single day

She called out her own mistake, saying, 'If I hadn’t chalked it all up to stress and fatigue, I would’ve caught this sooner.' Not exactly the kind of self-care Hollywood usually gets credit for, but at least she’s honest.

Bottom line, she’s been using her experience to tell fans and fellow hard-workers not to shrug off health symptoms, especially if things start sliding into the painful or downright dangerous. Or, as she put it in her first disclosure post, 'Don’t "suck it up" and transcend suffering; you deserve to be comfy.'

The Scene, the Cast, the Context

For those keeping track, 'King of Hell' is a pretty pivotal episode. Annie has a tense visit with her long-lost dad Rick (Tim Daly shows up as the estranged father), while Homelander keeps waging his bloody war on anything Starlight-adjacent. There’s a lot happening plot-wise, but now there’s this extra detail: Annie smiling through the pain was, well, Erin actually doing the same.

In short: cool superhero power, but the real feat was just making it through the day on set.