Tim Spector, a British epidemiologist and principal investigator of the Zoe COVID Symptom Study app, recently tweeted about the phenomenon and included a photo of COVID nails, writing, “Do your nails look odd? COVID nails are increasingly being recognized as the nails recover after infection and the growth recovers leaving a clear line. Can occur without skin rashes and appears harmless.”

Some people in the comments said they’ve definitely experienced this after having the coronavirus. “I noticed this and also hair loss 3 months after covid,” one wrote. “These were my post Covid nails! This was approx 2 months after the infection,” another said.

Plenty of others had questions in the comments section about COVID nails, what they look like, and if they’re something to worry about. Here’s what you need to know about COVID nails.

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What are COVID nails, exactly?
There’s actually a medical term for this—Beau’s lines. “When you have major physiological stress, like an illness, you basically have a shifting in the nail cycle,” New York City dermatologist Doris Day, MD, tells Health. You’ll usually see this in all of your nails (not just one nail) and maybe even in your toenails.

If you’ve had COVID-19, you won’t see this right away. Instead, Dr. Day says that it will likely take two to three months to show up.

What do COVID nails look like?
They’re grooves that run horizontally across your nail plate, according to Harvard Health. COVID nails/Beau’s lines can look like ridges, grooves, or indentations, Dr. Day says.

Had COVID-19 but don’t see COVID nails? This won’t necessarily happen to everyone, and it’s more apparent in some people than others. “Some people don’t see it in the nail because it’s not so obvious,” Dr. Day says.

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