Fever? Cough? Loss of sense of taste and smell? These are all common symptoms of COVID-19 infection.
But discolored and misshapen nails? Not so much, it seems.
However, in a small number of reported cases, patients’ fingernails discolored after a COVID-19 infection, developing a red half-moon pattern a few weeks later.
The pattern forms along the white area at the base of the fingernails and seems to appear earlier than other COVID-related nail phenomena. Multiple cases have been reported, and infected patients have noticed the discoloration less than two weeks after their diagnosis.
“Red half-moon nail patterns like this are generally rare, and previously haven’t been seen so close to the nail base. So having this pattern appear like this could exclusively be an indication of a COVID-19 infection,” Dr. Vassilios Vassiliou, senior clinical lecturer in cardiovascular medicine at University of East Anglia, and other researchers wrote in an article for The Conversation.
The researchers said the cause of the half-moon patterning is unclear, but speculate it could be due to blood vessel damage linked to the coronavirus or an immune response that causes tiny blood clots and discoloration.
The marks don’t appear to be a cause for concern and have lasted from a week to more than four weeks in patients.
Other people with COVID-19 have reported new horizontal indentations — called Beau’s lines — form at the bases of their fingernails or toenails, typically appearing four or more weeks after infection. Beau’s lines appear when an injury or severe illness interrupts growth at the area under the cuticle. Conditions such as uncontrolled diabetes and illnesses associated with a high fever such as measles and pneumonia have been linked to Beau’s lines.
A single groove in the line signals an episode of severe illness or stress while a series of lines indicates chronic illness or stress, according to News Medical, citing Dr. Liji Thomas. Patients develop a condition called onychomadesis if the nail stops growing for at least seven weeks and the indentation becomes very deep.
It’s likely that COVID-19 causes these Beau’s lines, Dr. Vassiliou and his colleagues wrote for The Conversation. Yet, they added that current evidence does not suggest a link between the type or extent of nail changes and the severity of COVID-19 infection.
People with COVID-19 have also reported orange discoloration of their nail tips, horizontal white lines on their nails known as “Mees’ lines,” and nails falling out.
In one case, an 89-year-old woman developed orange discoloration at the end of her nails weeks after a coronavirus outbreak hit her nursing home. The discoloration lasted after a month.
“Nails, like the skin, can provide important information regarding the presence and nature of systemic diseases. As a matter of fact, compelling evidence indicates that nails may presumptively be affected by or give clues about COVID-19 as much as the rest of the body,” European researchers from various institutions wrote in the case study last year.
Another patient, a 47-year-old man, had horizontal white lines appear on his nails, known as Mees’ lines or transverse leukonychia, 45 days after testing positive for COVID-19. Mees’ lines have been linked to systemic conditions such as heart failure and infectious diseases like malaria and tuberculosis.
A third case involved a 47-year-old woman whose nails loosened from their base and then fell out about three months after her hospitalization for COVID-19 illness. New healthy nails grew back although the woman didn’t receive treatment.
More cases of these nail conditions will have to be reported before researchers can definitely associate them to COVID-19, Dr. Vassilios Vassiliou and his colleagues noted.