35 COVID-19 symptoms to be aware of

As of June 10, the United States has passed two million cases of COVID-19, according to the . Since the first outbreak of the disease in Wuhan, China, in December 2019, scientific experts have been uncovering new information about the illness every day. However, many details remain unknown. Some of the biggest mysteries include what symptoms the illness causes. Early on, experts identified fever, coughing, and shortness of breath as key signs of COVID-19, but more mysterious symptoms have emerged in the months since.

Though states have begun to reopen public spaces, experts don't expect the pandemic to end anytime soon. Many don't expect a vaccine until next year at the earliest. Part of the reason the disease keeps spreading is that people with COVID-19 who don't have symptoms likely spread the novel coronavirus. About 40%-45% of people infected with the virus are asymptomatic, and they can transmit the virus for a longer amount of time than those with symptoms, possibly more than two weeks, according to an Annals of Internal Medicine published by the American College of Physicians on June 3.

COVID-19 is a respiratory disease, so many of the symptoms it causes are related to the lungs and breathing. However, some people also have gastrointestinal symptoms, such as nausea and vomiting; others report neurological symptoms, for example, headache and confusion. Some of the disease symptoms are relatively harmless, including loss of taste and smell. Others, such as stroke and heart complications, can be deadly. New information is unfolding about these symptoms every day, and the prevalence of these symptoms varies based on a study's methods and its location.

compiled a list of 35 COVID-19 symptoms that researchers have reported in scientific literature. Each symptom is confirmed by at least two peer-reviewed studies based on information gathered primarily in China, South Korea, France, and Italy at the beginning of the year and reported on in March and April. Learn what scientists know so far about the signs and symptoms of COVID-19.

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Fever above 100.4 degrees Fahrenheit

, or a temperature above 100.4 degrees, is one of the telltale signs of COVID-19 in all age groups. About 89% of people with COVID-19 develop a fever, though fewer聽 with the disease run a fever.

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Dry or wet cough

Along with fever, coughing is one of the two most prominent . As with fever, children with COVID-19 are less likely to present with a cough than adults.

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Shortness of breath or difficulty breathing

COVID-19 is a respiratory disease, and about 46% of people with the disease experience . Shortness of breath is one of the symptoms some Chinese scientists used to classify severe COVID-19.

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Feeling tired and low energy

COVID-19 patients with severe and nonsevere disease are almost equally likely to experience , with 38% experiencing the symptom, according to a study of 1,099 COVID-19 patients from hospitals across mainland China.

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Loss of smell

Loss of smell, known as anosmia, can be more common in women with COVID-19 and can occur in people with or without nasal symptoms such as congestion. It takes a median of seven days for those who lose it to recover their , according to a study of 3,191 patients in Daegu, Korea.

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Loss of taste

At first, experts didn鈥檛 consider loss of smell and taste important symptoms of COVID-19, but now they recognize them both as common. Estimates of prevalence vary widely, with one European study reporting that 88% of people with mild or moderate COVID-19 experience some ageusia, or .

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Mucus and phlegm

About 29% of people with COVID-19 produce mucus and phlegm. , as the bodily fluids are also called, can be coughed up or spit out and come from the throat and lungs.

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Sore and painful throat

are a common symptom in many illnesses and even allergies. About 11% of people with COVID-19 develop a sore throat.

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Rhinorrhea, or runny nose

A runny nose, or rhinorrhea, is present in a small percentage of COVID-19 cases. Though the numbers vary by study, about 8% have a , according to one study of 452 COVID-19 patients from a hospital in China.

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Nasal congestion or a stuffy nose

is a rarer symptom of COVID-19, affecting only about 5% of people with the disease. Runny nose and other nasal symptoms are not associated with loss of smell.

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Pneumonia, or infection of the lungs

The earliest cases of COVID-19 pneumonia in China were categorized as 鈥�,鈥� which means unknown origins. The disease itself involves lung tissue inflammation caused by an infection that leads to symptoms such as fever, difficulty in breathing, and a cough. Pneumonia is so common in COVID-19 that the disease, once recognized, was originally called COVID-19 pneumonia.

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Muscle and joint pain

About 21% of people with COVID-19 experience , or myalgia, according to a study of 452 patients from a hospital in China. Some may also experience joint pain.

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Nausea and vomiting

People with COVID-19 may develop gastrointestinal symptoms, though nausea and vomiting are uncommon. Only about 4% of people with the disease experience .

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Loose and watery bowel movements

Some people with mild COVID-19 only have digestive symptoms such as diarrhea. Those with diarrhea have it for an average of about five to six days. However, only about 5% of people with COVID-19 experience .

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Abdominal or stomach pain

COVID-19 patients with gastrointestinal symptoms may house the virus in their bodies for a longer period of time. is rare, affecting only about 5% of COVID-19 patients, with other studies reporting rates as low as 2%.

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Loss of appetite

About 21% of people with COVID-19 report , or anorexia, a symptom that it is more common in intensive care units (ICU) patients. Patients with digestive symptoms are more likely to shed the genetic material of the virus in their stool.

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Persistent pain or pressure in chest

Only two out of 99 COVID-19 patients from Wuhan, China, with concurrent pneumonia also . Of those with COVID-19 pneumonia, patients with severe or critical illness were more likely to have chest pain than those with ordinary disease.

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Heart complications and injury

About 20% of people hospitalized for COVID-19 at a hospital in Wuhan, China, . Those who did were more likely to die in the hospital. Heart injury can cause cardiac dysfunction and problems with the rate or rhythm of a person鈥檚 heartbeat.

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Blood clots in the lungs and elsewhere

Of 107 COVID-19 patients admitted to the ICU for pneumonia in a hospital in northern France, 22 had , called a pulmonary embolism. Another study of ICU COVID-19 pneumonia patients found that blood clots were most common in the lungs.

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Hypoxemia or a lack of oxygen in tissues

A small number of COVID-19 patients experience , a lack of sufficient oxygen in the blood, which can mean they need to be put on a ventilator to get enough oxygen. Hypoxemia is a symptom doctors sometimes use to confirm that patients are critically ill.

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Acute respiratory distress syndrome (ARDS)

COVID-19 patients who develop acute respiratory distress syndrome (ARDS), a type of respiratory failure, do so at a median of , according to a study of 138 hospitalized patients in Wuhan, China. About 20% developed the syndrome. ARDS is much more common in COVID-19 patients who die than those who survive.

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Disturbance in blood supply to the brain

About 1% of hospitalized COVID-19 patients in New York had an , the most common kind of stroke, which is usually caused by a blood clot that stops oxygen from getting to the brain. Scientists in another study found a higher rate of stroke in China, where four people had ischemic stroke and one had hemorrhagic stroke鈥攁 brain bleed鈥攐ut of 214 hospitalized patients.

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Confusion and delirium

Some COVID-19 patients have neurological symptoms, such as confusion and delirium. Out of 40 patients with COVID-19 and ARDS, , which can involve an 鈥渁cute change or a fluctuation in mental status, inattention, disorganized thinking, and altered level of consciousness,鈥� according to the report that appeared in The New England Journal of Medicine in April. In another group of patients with COVID-19 and pneumonia, only 9% experienced confusion.

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Headache

Some studies have shown a headache to be a minor symptom of COVID-19. About 8% of those infected with the coronavirus .

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Pink eye and other eye complications

Of 38 COVID-19 patients at a hospital in China, 12 had . People infected with the coronavirus may also experience inflammation in the blood vessels of their eyes.

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Shock, or inadequate blood flow to body tissues

About 6% of people with COVID-19 go into shock, which is when there is an inadequate amount of blood flow to tissues in the body. Of 36 patients sent to the ICU with COVID-19 in a Wuhan, China, hospital, .

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Acute kidney injury

Half of a percent of hospitalized COVID-19 patients have an acute kidney injury as a complication of COVID-19, though those with more severe disease are more likely to develop the injury. Of 113 COVID-19 patients who died in a hospital in Wuhan, China, 25% had .

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Chilblains, also known as COVID toes

Known colloquially as COVID toes, chilblains are sores or bumps on the skin. A WhatsApp group of 400 dermatologists collected 295 cases of skin conditions related to COVID-19, 146 of which were . This number is unusually high for the spring season in which the doctors reported their findings. The median age of people with chilblains related to COVID-19 is age 14, and the feet alone are affected in most cases.

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Rashes and skin lesions

At the Lecco Hospital in Lombardy, Italy, 18 of 88 patients experienced due to COVID-19. A red rash was reported by 14 of these patients, typically on the trunks of their bodies, which wasn鈥檛 related to the severity of the disease. Additionally, 149 of the 295 cases identified by the dermatologist WhatsApp group were some other skin issue, such as a .

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Coughing up blood

Hemoptysis, or , is a rare symptom of COVID-19 that occurs in about 5% of hospitalized patients, according to a study of 41 patients in Wuhan, China. Among 62 patients admitted to a hospital elsewhere in China, 3% were coughing up blood at the onset of their illness.

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Dizziness, or feeling unbalanced

In patients with central nervous system complications due to COVID-19, dizziness is one of the most prominent symptoms, according to a study of 214 hospitalized patients in Wuhan, China. About 16% of people with the disease report dizziness and mild headache, according to a of 51 COVID-19 patients in China.

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Chills, or feeling cold with no good reason

About 12% of hospitalized COVID-19 patients experienced , according to a study of 1,099 patients across mainland China. Among hospitalized patients who are not critically ill, chills are a risk factor for the disease worsening.

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Multisystem inflammatory syndrome in children

The , which is similar to Kawasaki disease and causes inflammation throughout the body, occurs in children and teenagers. Though children generally have less severe COVID-19 symptoms than adults, this syndrome can cause .

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Guillain鈥揃arr茅 syndrome

is a rare condition in which the immune system malfunctions and attacks the body鈥檚 nerves. There are only 12 cases of Guillain鈥揃arr茅 syndrome connected to COVID-19. The syndrome typically arises about 10 days after the onset of COVID-19.

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Brain damage resulting in an altered mental state

Of 113 people who died of COVID-19 in Wuhan, China, 20% had hypoxic encephalopathy, or damage to the brain that makes someone act like they're in an altered state. Several other of the condition suggest that it may be connected to COVID-19.