Not all of the patients had Covid-19, she said, but the ones who did tended to progress very quickly from one or two bald patches to “losing hair all over the body,” including eyebrows and eyelashes. She said that might be because the storm of inflammation that some Covid patients experience elevates immune molecules linked to conditions like alopecia.
Experts don’t know exactly why stress triggers these conditions, which affect both women and men. It might be related to increased levels of cortisol, a stress hormone, or to effects on blood supply, Dr. Hogan said.
The hair loss itself can cause more stress, Dr. Khetarpal said, especially for women, whose hair is often more closely tied to identity and self-confidence.
“It’s your trademark,” said Mary Lou Ostling, 77, a retired educator who lives in the Stuyvesant Town neighborhood of Manhattan. She was hospitalized for Covid-19 for eight days in the early spring and later noticed that “my hair started coming out in chunks,” she said. “I always was clearing hair out of the comb, brush, the sink.”
Ms. Ostling said she also could tell that her hair wasn’t growing much because she wasn’t seeing roots that contrasted with the color she had previously dyed it.
“I’ve always had very long, very thick, very curly hair,” she said. But in July, “I simply had a lot it all cut off. I couldn’t deal with it anymore.”
When she came home from the hairdresser, she said, “my husband was just staring at me. He said, ‘I think I have a different wife.’ It was very depressing.” She said she has finally begun to detect some hair growth.