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Unusual Symptoms of COVID-19 You Need to Know About

From nose to toes, doctors continue to discover uncommon signs of coronavirus infection

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Fever, cough and shortness of breath are not the only warning signs of a coronavirus infection, even if they are some of the most common. Over the past year doctors have documented a handful of otherwise unexpected symptoms in patients with COVID-19, the illness caused by the coronavirus.

Some are reporting red or purple lesions on patients’ hands and feet; others are treating people with diarrhea and severe appetite loss. There are also patients who have lost their sense of taste and smell. These symptoms, strange as they may seem, reinforce what experts around the world have come to realize: The coronavirus (SARS-CoV-2) is capable of causing more than a respiratory illness; it can launch a full-body attack.

“It takes a while for the full range of symptoms to kind of be known” when you’re dealing with a new virus, explains Lisa Winston, M.D., an epidemiologist and professor of clinical medicine at the University of California, San Francisco (UCSF). At the start of the U.S. outbreak, the focus was primarily on treating the sickest patients, many of whom experienced classic respiratory symptoms and needed help breathing. “And then, as time went on and people saw more cases, they started to recognize some of the things that are a bit less typical,” Winston says.

Here are some uncommon signs of COVID-19 that fall outside the hallmark symptoms.

‘COVID toes’

If you had asked dermatologist Esther Freeman, M.D., in 2019 what type of skin ailment a future viral pandemic might bring about, she never would have predicted red- and purple-colored toes that swell, burn and itch. But that’s exactly what she and other experts have seen in patients during the pandemic, leading this unusual symptom to be dubbed “COVID toes.” 

“The good news is, they do go away,” says Freeman, director of Massachusetts General Hospital Global Health Dermatology and assistant professor of dermatology at Harvard Medical School, who is also overseeing an international registry that catalogs the dermatological manifestations of COVID-19. “So we’re not seeing that this is going to cause permanent damage.”

Another plus: The majority of people with COVID toes — which Freeman likens to chilblains (also called pernio), an inflammatory skin condition that often occurs after exposure to very cold temperatures — don’t experience other symptoms of a coronavirus infection and don’t require hospitalization for care. “Many patients are developing these toe lesions well after their infection, or they’re otherwise completely asymptomatic, except for the toes,” she adds.

Though most cases of COVID toes occur in the feet, the hands can be affected, too. Rashes similar to those that result from hives and chicken pox have also been reported in people who test positive for the coronavirus.

If you notice a lesionlike rash on your hands or feet, contact your doctor or dermatologist about your symptoms, since it could signify a coronavirus infection. That said, it’s important to keep in mind that “not everything on your toes right now is from COVID,” Freeman says. “There’s certainly lots of other things that can appear on the feet, and there’s things that can even look similar,” which is why it’s important to talk with an expert. There is no specific treatment for COVID toes, but a high-potency topical steroid might reduce inflammation.

Loss of taste or smell

On the CDC’s list of common COVID-19 symptoms, one stands out. In addition to fever, chills and a sore throat, the public health agency recognizes new loss of taste or smell as evidence of a coronavirus infection.   

“People who have colds, if they get a really stuffy nose, they may complain of lack of smell, but, you know, that’s sort of an unusual [symptom] right now in the absence of COVID,” UCSF’s Winston says. But it may be one of the best indicators of a coronavirus infection.

A study published in the journal Nature Medicine tracked more than 2.5 million participants who reported their potential symptoms of COVID-19 on a smartphone app. About 65 percent of people who tested positive for COVID-19 reported loss of taste and smell, making it one of the strongest predictors of the illness among those studied. Similarly, researchers from the University of California, San Diego, found that smell and taste loss were reported in 68 and 71 percent of COVID-19–positive subjects, respectively.

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Diarrhea, nausea, vomiting and severe appetite loss

COVID-19 is producing symptoms of diarrhea, nausea, vomiting and appetite loss in a number of patients young and old. A study out of Stanford University School of Medicine found that nearly one-third of 116 patients infected with the coronavirus reported mild gastrointestinal (GI) symptoms. Earlier reports showed that among roughly 200 patients in China, more than half experienced diarrhea, nausea or vomiting. The Centers for Disease Control and Prevention (CDC) has also acknowledged GI issues on its list of COVID-19 warning signs.

Hair Loss: Another COVID-19 effect?

More than 20 percent of COVID-19 patients report hair loss two to four months after infection, studies show. Doctors say it’s likely a reaction to the stress brought on by the disease, rather than a symptom of the virus itself.

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“There’s no question at this point that GI symptoms can be a manifestation of COVID-19,” says William Chey, M.D., professor of gastroenterology and nutrition sciences at the University of Michigan. And oftentimes these symptoms can come on even in the absence of “the more typical and recognized” markers of a coronavirus infection, such as fever and cough, he adds.

Experts point to a few explanations for the tummy trouble. Chey says the virus can directly infect the cells that line the GI tract, which is why some patients can test positive for the virus with a stool sample, even if results from a nasal swab come back negative. GI issues could also be an indirect result of the body’s fight against infection.

If you don’t have a history of GI trouble and experience a sudden onset of diarrhea, nausea, vomiting or loss of appetite — with or without other COVID-19 symptoms — check in with your doctor. Your symptoms might warrant a coronavirus test.

And if you are diagnosed with COVID-19, consider confining yourself to your own room and bathroom, separate from others in your house. 

Headaches, dizziness and confusion

Beyond loss of taste and smell, doctors are noting a growing list of neurological effects in COVID-19 patients. Other indicators of the illness include dizziness, headache and confusion.

In fact, a study in JAMA Neurology found that more than 36 percent of 214 patients in Wuhan, China, experienced neurological symptoms during their bout of COVID-19. More recent research published in Annals of Clinical and Translational Neurology found that neurological manifestations — headaches, dizziness, confusion, etc. — were present in 42 percent of patients at the onset of COVID-19 symptoms and in 82 percent of patients at any time during the disease course.

For older adults, in particular, these neurological effects can be just as devastating as the pulmonary impacts of a coronavirus infection, says XinQi Dong, M.D., director of the Institute for Health, Health Care Policy and Aging Research at Rutgers University-New Brunswick. They can also be easily overlooked or dismissed as dementia or other diseases common with aging.

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“We’re trying to be very vigilant and broad in our thinking” when a patient comes into the emergency room with confusion or change in mental status, say Neal Sikka, M.D., an associate professor of emergency medicine at George Washington University in Washington, D.C. “That could be some other type of infection; it definitely could also be a presentation of COVID. And so we are trying to do rapid testing on those patients to identify them early.”


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Separate from the neurologic complications mentioned above, some COVID-19 patients with no history of mental health issues have experienced mild to severe hallucinations.

Experts are not sure what, exactly, is causing the symptom. In some patients, hallucinations may be part of delirium that can sometimes accompany a critical illness or a long hospital stay, especially among older adults. In others, the visions and voices occur on their own, and doctors say the symptom could be due to chronically low levels of oxygen going to the brain or may be a result of the virus causing a direct attack on the brain. Inflammation triggered by the virus may also be to blame.

Unlike other coronavirus symptoms, which can have lasting effects, hallucinations and delusions usually fade when the infection does, experts say. Low doses of antianxiety or antipsychotic medications can help patients find relief in the meantime.

Blood clots

Health care professionals have taken note of a troubling trend among coronavirus patients: blood clots. Some studies have found that as many as 30 percent of people with severe cases of COVID-19 experience clotting complications. Clot specialist Alex Spyropoulos, M.D., estimates that the number is even higher. The internist and professor of medicine at the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell says that as many as 40 percent of patients who are hospitalized with COVID-19 die from blood clots, including micro clots, and the destruction they can cause (heart attack, stroke, lung damage and the like).

“The risk of blood clots are anywhere from about three- to sixfold or greater, more than we’re used to seeing,” Spyropoulos adds. “It has us all in the academic community a little bit befuddled, because it’s one of the most aggressive diseases with respect to blood clots that we’ve ever seen.”

As for what’s behind the clots, the answer is still unclear. They may be directly caused by the coronavirus and its interaction with the clotting pathway, Spyropoulos says. A hyper immune response is another explanation experts are exploring. Then there’s the state of being critically ill, which Babak Navi, M.D., division chief for stroke and hospital neurology at Weill Cornell Medical College and a neurologist at New York-Presbyterian Hospital, says can provoke clotting.

“It’s well known that infections and inflammations are potent triggers and risk factors for clotting events, including stroke,” Navi explains.

If you have clotting issues, the best thing you can do — especially during the pandemic — is take your blood thinner medication as prescribed, Spyropoulos advises. And if you experience symptoms of a blood clot (pain, redness, swelling) or a stroke (confusion, dizziness, numbness), “take them extremely seriously and go right to the emergency department,” Spyropoulos adds.

Hearing loss

Researchers are looking into a possible connection between COVID-19 and hearing loss. Several reports document patients who have experienced hearing problems that coincide with a COVID-19 diagnosis. Often these issues, which include tinnitus, or ringing in the ears, persist even after other symptoms of the illness subside.

The virus, SARS-CoV-2, has also been detected in the middle ear of COVID-19 patients, as reported in JAMA Otolaryngology – Head and Neck Surgery. With several other viruses known to cause hearing loss, the study’s corresponding author, C. Matthew Stewart, M.D., said the findings raise some concerns.

“If there is an active viral infection in that part of the body, you could get the whole host of symptoms associated with other types of viral infections in that area,” including inflammation in the ear that could impair hearing or cause tinnitus, dizziness and imbalance, explains Stewart, an associate professor of otolaryngology, head and neck surgery at Johns Hopkins School of Medicine.

Experts caution there’s not enough evidence yet to draw a direct link between a SARS-CoV-2 infection and hearing problems. Other factors, such as medications used to treat COVID-19, many of which are ototoxic, or toxic to the ear, could contribute to the complication.

“And that’s going to confound our understanding of the difference between hearing loss that’s caused by a viral infection or hearing loss caused by the usage of an ototoxic medication that’s given for therapeutic reasons,” Stewart says.

Being critically ill can also usher in hearing loss, researchers point out. And public health efforts, such as masks and physical distancing recommended to slow the spread of the virus, can reveal previously overlooked hearing issues.

Elias Michaelides, M.D., director of the cochlear implant program and medical director of audiology and otolaryngology at Rush University Medical Center in Chicago, has seen a number of patients in recent months who say their hearing has worsened since the start of the pandemic.

“It turns out that their hearing hasn’t changed,” but their ability to communicate with others has, he says. “When you’re wearing a mask, it muffles your voice and sometimes can make it harder for other people to hear you,” Michaelides points out.

Masks also interfere with people’s ability to pick up on visual cues when another person speaks. “For most people, it’s not much of an issue. But in elderly patients who may already have some hearing loss, this can sometimes push them to the point where they’re having difficulty understanding speech,” he adds.

As researchers continue to study the short- and long-term effects of a SARS-CoV-2 infection, experts say the public can expect to see more hearing-specific studies surface. In the meantime, if you experience worsening or sudden hearing loss, contact your doctor right away. Early treatment can prevent permanent damage in some instances, Michaelides says. Your doctor may also recommend tools, such as hearing aids, to improve your quality of life.

High Blood Sugar

Some older adults are showing up to emergency rooms and testing positive for COVID-19 with few complaints other than high blood sugar (or hyperglycemia), a recent study in The American Journal of Emergency Medicine found. 

It’s important to note that hyperglycemia is common among patients with any infection, not just a coronavirus infection. “Even more moderate degrees of infectious disease can relate to a higher blood sugar,” especially in patients with diabetes or prediabetes, whose glucose levels go up when they’re sick, explains Robert Eckel, M.D., president, Medicine & Science, at the American Diabetes Association.

Even still, endocrinologists have been seeing “really impressive” rates of hyperglycemia and insulin resistance “across many hospital systems in the country in patients with COVID or suspected COVID” since the start of the pandemic, says Eve Bloomgarden, M.D., assistant professor of medicine in the Division of Endocrinology, Metabolism and Molecular Medicine at the Northwestern University Feinberg School of Medicine. 

Sometimes these patients have diabetes or prediabetes and just haven’t been diagnosed. However, the high incidence of hyperglycemia also suggests that the new coronavirus has “a really impressive effect on the metabolic control,” Bloomgarden adds. In fact, some doctors, including Eckel, are studying whether COVID-19 can even trigger a new type of diabetes in patients who previously did not have the disease.

How can you tell if your blood sugar levels are higher than normal? Diabetics who check their blood glucose regularly can track these trends themselves. Patients who don’t have diabetes can look out for increased thirst, increased urination, blurred vision and weight loss — all are signs of hyperglycemia, which can be confirmed with a blood test.

If you notice your blood sugar shooting up or are concerned you have symptoms of hyperglycemia, contact your doctor right away. You may need extra care if a coronavirus infection is the underlying cause, since people with hyperglycemia and COVID-19 tend to fare worse than other COVID-19 patients, Eckel points out. “In other words, people tend to get sicker; they have more outcomes that are less favorable, including death,” he adds.

Because of this, Bloomgarden says it’s especially important for diabetics to stay on top of managing their blood sugar levels during the pandemic and to practice “public health measures to avoid getting infected in the first place.” 

Eckel and Bloomgarden are also warning health care providers that high blood sugar in a patient could be enough to warrant a coronavirus test and the use of personal protective equipment, even in the absence of other telltale symptoms. “This could be another sign of something [going on] underneath the surface,” Eckel says.


While relatively rare, physicians and researchers have seen myocarditis, or inflammation of the heart, in some people who previously had COVID-19. A May 2021 study looking at nearly 1,600 U.S. college athletes who had COVID-19 found that 2.3 percent went on to develop myocarditis, which if left untreated can cause permanent heart damage. In several of these cases, the heart condition did not come with symptoms such as chest pain or a rapid heart rate; it was identified with cardiac magnetic resonance imaging.

When it comes to myocarditis, athletes need to take special care because “if they go back to play too soon, they can have worsening of heart disease,” says Saurabh Rajpal, M.D., an assistant professor of cardiology at The Ohio State University and a co-author on the study, published in JAMA Cardiology. Sometimes, this can result in sudden cardiac death.

Many viruses have been linked to myocarditis, and experts are still working to better understand the heart condition’s connection to SARS-CoV-2. In the meantime, Rajpal says if you had COVID-19 and start to notice chest pain, shortness of breath or a racing heart while doing the same level of exercise that you did before your infection, contact your health care provider “and get checked out.”

“I think it's important to be aware that this severe complication can happen after COVID,” he says.

Editor’s Note: This article, originally published May 13, 2020 has been updated to reflect new information. Stacey Colino contributed reporting.

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