Erin Moriarty details June 2025 Graves’ diagnosis during The Boys

Erin Moriarty said she was diagnosed with Graves’ disease in June 2025 while filming the final season of The Boys, and she wished she had been in a better physical and emotional state while playing Starlight. Her account turns one cast member’s health issue into a production-side reality: the illness hit during season 5, not after it.

June 2025 diagnosis

Moriarty publicly revealed the diagnosis in June through social media and later said doctors identified Graves’ disease after she first thought her symptoms were stress and exhaustion from work. Graves’ disease is an autoimmune condition that affects the thyroid gland, and she said treatment helped her start to improve.

“It’s important for me to be vocal about autoimmune diseases. I was starting to feel so ill, and even though I come from a family of doctors, no one thought to say, ‘Go get your levels tested. It was like I was offline for the first six to seven episodes, and then I came back online. I finally felt present at the very end of season five.”

Episode 4 and season 5

The hardest stretch came around the time she shot the episode with her father, episode 4. Moriarty said, “Around the time that I shot the episode with my father (episode 4), I started to get really sick, and we didn’t know what it was…All my dreams were coming true. But simultaneously, my health was plummeting, and it was a very scary moment in time..This character’s moment with her father was the most important moment for me, I just wish I could have shown up for her in a more whole state.”

That timing matters because she said the illness affected a major emotional storyline in season 5. She said she was offline for the first six to seven episodes, then came back online by the end of the season, which means the performance viewers saw was shaped by a recovery process happening in real time.

Mother, treatment, and return

Moriarty said she reached out to her mother during the worst of the illness, and her mother came to help her quickly after receiving the message. She also said support from the cast and crew helped her through the hardest days of filming, a practical reminder that production schedules still have to absorb health problems even when the episode count keeps moving.

She said she has not been able to watch the final season because it is tied to that difficult period, but she finally felt present at the very end of season five. The takeaway for viewers is plain: the season was completed, but one of its central performances was filmed while Moriarty was dealing with a diagnosis that forced her to rebuild her energy episode by episode.