Science is only beginning to understand the long-term effects of COVID-19, which can wreak havoc on the lungs and other internal organs, and even cause neurological issues. Many COVID-19 patients are experiencing ongoing skin symptoms weeks or even months after a positive diagnosis.
These “long-haulers,” also known as “long-COVID” patients, can experience fatigue, headaches, and difficulties breathing for weeks after infection. Another persistent commonality among patients is a wide variety of skin symptoms, including so-called “COVID toes.”
Research presented at the 29th European Academy of Dermatology and Venereology (EADV) Congress—which took place virtually in Vienna from Oct. 28-Nov. 1, 2020—found that various skin symptoms can persist in patients for months. In addition to COVID toes, these symptoms can include rashes, hives, and scaly papules and plaques known as papulosquamous eruptions.
The International League of Dermatological Societies and the American Academy of Dermatology presented the findings in a joint effort, which examined data collected from an international COVID-19 Dermatology Registry of more than 1,000 patients from 41 countries. Of the 224 patients who made up the study’s focus, skin symptoms lasted an average of 12 days, with some lasting up to 150 days.
Many patients continued to experience skin conditions long after their initial infection had cleared up. While COVID toes lasted for about two weeks in most patients, six patients had symptoms lasting at least 60 days, and two had them for more than 130 days.
Persisting skin conditions in COVID patients are unusual when compared to other viruses or diseases such as measles or chickenpox. Skin symptoms typically clear up and go away once the condition goes into remission.
Another curious finding discovered that the skin conditions associated with coronavirus varied wildly depending on the infection’s severity. For example, COVID toes are commonly associated with milder cases. Only 16% of patients in the registry experiencing COVID toes received hospitalization at any point.
Dr. Esther Freeman, director of Global Health Dermatology at Massachusetts General and an assistant professor of dermatology at Harvard Medical School, believes that COVID toes can provide insight as a reaction to the way the immune system handles the virus.
“In contrast, some of the other dermatologic conditions travel with much more severe COVID-19,” Freeman told Verywell Health. “One example of that is something called retiform purpura, which are net-like, bruise-like eruptions that are actually caused by clots.” Freeman found that 100% of patients with retiform purpura required hospitalization, as blood clots are “one of the most severe and dangerous symptoms of COVID-19.”
“There are many different types of skin manifestations of COVID-19, which is very interesting,” Freeman added. “It’s actually hard to think of another virus that causes so many different types of skin findings.”
Why does COVID-19 cause skin symptoms?
Researchers are still learning why some patients develop skin symptoms, but they believe inflammation plays a significant role. It’s particularly evident when it comes to COVID toes and chilblains — also known as pernio — the painful inflammation of small blood vessels in the skin. These can cause itching, red patches, swelling, and blistering, primarily on the hands and feet. Inflammation typically occurs as a response to the body fighting a virus.
Inflammation only explains some of the skin conditions associated with long COVID, however, and it does not explain the more severe conditions such as retiform purpura.
“There are several types of skin rashes and skin manifestations that we’re seeing that do appear to be caused by inflammation, but there are also several that are not,” Freeman said. “So [skin symptoms] are not universally caused by inflammation. You have to drill down on the different types of skin manifestations.”
“With COVID toes, we’re seeing this kind of persistent inflammation,” she continued. “It certainly begs the question of why do some patients seem to have these really long-standing, persistent inflammatory effects? My suspicion is that it’s not a direct viral effect that many months out; clearly, the virus has triggered some other process in the body that’s continuing.”
“I think we need to be reassuring to most of our patients who develop pernio or chilblains in the setting of COVID-19. Both in the registry and in my own personal cohort of patients, symptoms resolved after a median duration of 15 days. I do think that’s an underrepresentation, as we’ve seen lots of our patients lasting four and six weeks. But for most of our patients, the pain and discomfort only lasts about a week.”