Dani Bloom, 2022 The New York Times Company / Photo: MARIA ATHANASIOU

Here we are, after years of the pandemic, many now know everything in detail symptoms Covid-19 illnesses: terrible sore throat, persistent cough, congestion, fever and exhaustion. But there is a small group of people who develop less common symptoms that sound like spells from a children’s book: hairy tongues, black toes, a rash on the face.

“Every infectious disease has common and unusual manifestations,” explains Dr. Mark Mulligan, an epidemiologist at New York University Langone Medical Center. As we learn more about the coronavirus, he says, we can better understand the causes of these unusual symptoms, but until then, we’re mostly just guessing.

Strange symptoms have accompanied Covid-19 since the start of the pandemic: Loss of smell and taste is a warning sign of the disease, which can also disrupt the menstrual cycle, an undesirable side effect many women report after getting vaccinated.

A study of more than 60,000 people who contracted the virus and reported their symptoms found that a small percentage of them had tinnitus, eye irritation, itching, a rash on the face or lips, hair loss, and unusual pain in the curls. A larger survey of 600,000 people in the UK found that some of those who contracted Covid-19 had sores and blisters on their feet and body numbness, among other things.

Doctors are not sure why some people experience these unusual symptoms. Genetics may play a role, Mulligan notes, and vaccinations may also be involved, as an unvaccinated person can get sicker and have different symptoms. The scientists also found that the coronavirus can enter the circulatory system of a small group of people, meaning that the virus can enter various organs of the body and thus cause symptoms that extend beyond the respiratory system.

Treatments against the virus, such as Paxlovid, can treat symptoms such as rashes, perhaps because they can reduce the amount of virus in the blood, notes Dr. Kelly Gimbaud, an epidemiologist at Johns Hopkins School of Medicine. But it is not yet clear whether these symptoms are caused directly by the virus or the body’s response to it.

Inflammation may also be to blame, notes Dr. Peter Chin-Hong, an epidemiologist at the University of California, San Francisco. If the virus infects many areas of the body through the bloodstream, cells of the immune system flock to these areas, the professor explains. This means that, for example, an ear that is not normally affected by a virus can become inflamed, malfunction, or even hurt.

Covid-19 also leaves patients very weak, he says, causing pathogens lurking in the body from previous infections, such as herpes simplex or shingles, to reactivate, causing rashes and the like.

A third theory is that Covid-19 disease may be accompanied by stress — quarantine stress, loss of income, fear of long-term health problems — that can cause symptoms such as hair loss and rashes, Chin-Hong points out. . . .

Read what else we know about the causes of some of these symptoms and possible treatments.

→ hairy tongue

Healthy tongue cells renew themselves quickly, Chin-Hong notes, but if old cells remain and overlap, a dark, dense, furry layer forms, often referred to as a hairy tongue. Even before Covid-19, doctors were seeing patients with hairy tongues due to viral infections, smoking, antibiotic use and poor oral hygiene, he says, adding that “it’s much more common than you think.”

“I know it looks pretty intimidating,” he admitted, but the discomfort is temporary. Some people also experience a burning sensation in their mouth. For those experiencing these symptoms, there is no need to panic, says Dr. Chin-Hong. They can simply use a tongue scraper or a toothbrush to remove these cells and then take good care of their oral hygiene to make sure it doesn’t happen again.

The professor notes that in rare cases, people with Covid-19 can also develop aphthous ulcers, which are associated with weak immunity or the use of antibiotics. Doctors usually proceed with a diagnosis through a clinical examination of the cheeks, tongue, or mouth and prescribe antifungal treatment for 10 to 12 days.

→ tingling sensation

When people feel pins and needles piercing their skin, it may be due to nerve inflammation as they fight infection. It’s also possible that the virus can affect peripheral nerves, such as those in the arms and legs, says Dr. Gimbo. The same thing happens with herpes. “What we don’t know is what is happening directly due to the virus and what is due to inflammation,” he explained. “That’s what we’re trying to figure out.”

For many people, this tingling goes away after a few days, he says. If patients experience pain, he adds, they should check with their doctor, who may recommend some medication. People who have persistent nerve pain even after recovering from the virus should see a doctor, says Dr. Mark Sala, co-director of Northwestern Medicine’s Covid-19 Comprehensive Center.

→ Rash

Viruses are known to cause rashes, says Dr Sala, noting that he has observed a wide range of skin irritations in Covid-19 patients. The American Academy of Dermatology lists itchy bumps, chickenpox-like blisters, rashes, and simple bumps as possible skin problems associated with the virus. If you have a rash that doesn’t go away after you get better, Dr. Sala recommends seeing a dermatologist.

→ Hair loss

Any kind of physical or psychological stress can trigger hair loss, says Shilpi Hetarpal, a dermatologist at the Cleveland Clinic. He acknowledges that it is not clear whether the Covid-19 infection itself, or the stress associated with it, leads to hair loss in some people. If you find yourself in this position, having lost your hair during or after an illness, don’t panic, she advises, adding: “It won’t be permanent, it will come back, it will just take a while.”

→ Sock with Covid-19

Scientists still disagree about what causes “covid-19 on the toes,” the frostbite-like rash and blisters that some people get on their feet and toes, causing swelling and bruising of the toes. One theory is that people with Covid-19 may have blood clots in microvessels that block blood flow and cause discoloration, says Dr. Sala.

He adds that patients usually experience this symptom during the acute phase of the infection, and it usually resolves shortly thereafter. The American Academy of Dermatology recommends using a hydrocortisone cream for treatment. Like all unusual symptoms of Covid-19, no matter how annoying they are, the swelling goes away on its own — for reasons doctors aren’t entirely sure.