Feeling sick can be especially concerning these days. Could your sniffles be caused by COVID-19? Or the flu? A cold? Or maybe allergies?

Determining the cause of an illness can be tricky because many share some symptoms. They can leave you sniffling, coughing, and feeling tired. But there are important differences.

Figuring out what’s making you sick can help you recover and prevent spreading sickness to others.

Influenza (flu) is a common contagious viral respiratory illness that can affect the nose, throat, and lungs. Flu viruses spread mainly by droplets made when people with flu cough, sneeze or talk. Flu illness can vary from mild to severe. When severe, flu can result in hospitalization and even death. Some people are more likely to suffer serious flu complications, including older adults, pregnant people, young children and people with certain chronic health conditions. CDC recommends that everyone 6 months and older get an annual flu vaccine. Flu vaccination can prevent flu illness and its potentially serious complications. While flu vaccination varies in how well it works, an annual flu vaccination is the best way to protect against flu. However, if you get the flu, there are medications that can help treat it, and which are particularly important for some groups of people. Influenza antiviral drugs are prescription medications that can reduce severity and duration of flu illness, and also might prevent serious flu complications. CDC recommends influenza antiviral treatment for people who are very sick with flu and people with flu symptoms who are at higher risk of developing serious flu complications.

Key Facts

• The severity of flu seasons can differ substantially from season to season.
• You may be able to spread flu to someone else before you know you are sick, as well as while you are sick.
• Hundreds of thousands of people are hospitalized with flu each year.
• People with certain long-term health conditions, like asthma or diabetes, are at higher risk of serious flu complications.
• Take 3 steps to fight flu: get vaccinated, take everyday preventive actions, and take antiviral medicines if prescribed.

Are you at higher risk?

Certain people are at a greater risk of developing serious flu complications. These groups of people include: children younger than 5, adults 65 years of age or older, pregnant women, and people with certain chronic health conditions.

Prevention Tips

• An annual flu vaccination is the best way currently available to reduce the risk from flu and its potentially serious complications. As long as flu viruses are spreading, you can still benefit from a flu vaccine.
• Avoid people who are sick. Stay home when you are sick with flu for at least 24 hours after your fever is gone, except to get medical care or other necessities. Your fever should be gone without the need to use a fever-reducing medicine, such as acetaminophen.
• Avoid touching your eyes, nose, or mouth. Though less common than spread through droplets that come from the nose and mouth when people cough, sneeze, or talk, flu viruses can also when a person touches something that is contaminated with flu viruses and then touches their eyes, nose, or mouth.
• Wash your hands regularly with soap and water. If soap and water are not available, use an alcohol-based hand rub.
• Check with your doctor promptly if you are at higher risk of developing serious flu complications and you get flu symptoms. Your doctor may prescribe influenza antiviral drugs to treat your flu illness, which can lessen the severity of your illness, shorten the amount of time you are sick and help prevent serious flu complications.

COVID-19 is a respiratory disease caused by SARS-CoV-2, a coronavirus discovered in 2019. The virus spreads mainly from person to person through respiratory droplets produced when an infected person coughs, sneezes, or talks. Some people who are infected may not have symptoms. For people who have symptoms, illness can range from mild to severe. Adults 65 years and older and people of any age with underlying medical conditions are at higher risk for severe illness. People ages 5 years and older should get COVID-19 vaccines to prevent getting and spreading the illness. Everyone ages 16 and older can get a booster shot.

Key Facts

• The virus that causes COVID-19 can spread through respiratory droplets when an infected person coughs, sneezes, or talks.
• Symptoms may appear 2-14 days after someone is exposed to the virus and can include fever, chills, and cough.
• Some people who are infected may not have symptoms, which is why everyone should take everyday preventive actions.
• Anyone can have severe illness from COVID-19, especially older adults and people of any age with underlying conditions.

Social Distancing

Social distancing, also called “physical distancing,” is one of the best ways to avoid being exposed to COVID-19 and slowing its spread. To practice social or physical distancing, stay at least 6 feet (about 2 arms’ length) from other people, do not gather in groups, stay out of crowded places, and avoid mass gatherings.

Face Coverings Dos & Don'ts

CDC recommends wearing masks in public settings where other social distancing measures are difficult to maintain, such as grocery stores, pharmacies, and gas stations. Masks may slow the spread of the virus and help people who have the virus and do not know it from transmitting it to others.

Prevention Tips

• Get a COVID-19 vaccine if you are ages 5 or older. COVID-19 vaccines are safe, effective, and free!
• Wash your hands with soap and water for at least 20 seconds. If soap and water are not available, use a hand sanitizer that contains at least 60% alcohol.
• Avoid close contact with people outside your home. Stay at least 6 feet (about 2 arms length) from others.
• Wear a mask in public, even if you don’t feel sick. It will help protect others in case you are infected.
• Cover your coughs and sneezes with a tissue or the inside of your elbow. Throw used tissues in the trash and then wash your hands with soap and water for at least 20 seconds.
• Clean and disinfect frequently touched surfaces. This includes tables, doorknobs, light switches, countertops, handles, desks, phones, keyboards, toilets, faucets, and sinks.
• Stay home if you have symptoms such as fever, cough, shortness of breath.
• Seek emergency medical care if you develop severe symptoms, such as trouble breathing, chest pain, new confusion, inability to wake or stay awake, or pale, gray, or blue-colored skin, lips, or nail beds, depending on skin tone.​

Most people get colds in the winter and spring, but it is possible to get a cold any time of the year. Symptoms usually include sore throat, runny nose, coughing, sneezing, headaches, and body aches. Most people recover within about 7-10 days. However, people with weakened immune systems, asthma, or conditions that affect the lungs and breathing passages may develop serious illness, such as pneumonia. Common colds are the main reason that children miss school and adults miss work. Each year in the United States, millions of people get the common cold. Adults have an average of 2-3 colds per year, and children have even more.

Key Facts

• Every year, adults have an average of 2–3 colds, and children have even more.
• Many viruses can cause colds, but rhinoviruses are most common. Infections spread through the air and close personal contact.
• There is no cure for a cold. To feel better, you should get lots of rest and drink plenty of fluids.
• Symptoms of a cold usually include sore throat, runny nose, coughing, sneezing, headaches, and body aches.
• To reduce your risk of getting a cold, wash hands often for at least 20 seconds with soap and water and avoid touching your face with unwashed hands.​

Protect Yourself and Others

Wash your hands often with soap and water for at least 20 seconds. If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60% alcohol. Viruses that cause colds can survive on your hands, and regular handwashing can help protect you from getting sick.

How to Feel Better

There is no cure for a cold. To feel better, you should get lots of rest and drink plenty of fluids. Over-the-counter medicines may help ease symptoms but will not make your cold go away any faster. Always read the label and use medications as directed. Talk to your doctor before giving your child nonprescription cold medicines, since some medicines contain ingredients that are not recommended for children.

When to See a Doctor

You should call your doctor if you or your child has one or more of these conditions: a temperature higher than 100.4°F, symptoms that last more than 10 days, or symptoms that are severe or unusual. If your child is younger than 3 months of age and has a fever, you should always call your doctor right away. Your doctor can determine if you or your child has a cold and can recommend therapy to help with symptoms.

Get Smart

When you have a cold, mucus fills your nose, causing runny nose, congestion, and mucus to drip down your throat (post-nasal drip), which can cause a sore throat and cough. This mucus helps wash the germs from the nose and sinuses. After two or three days, mucus may change to a white, yellow, or green color. This does not necessarily mean antibiotics are needed.

Prevention Tips

• Wash your hands often with soap and water. Wash them for at least 20 seconds, and help young children do the same. If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60% alcohol. Viruses that cause colds can stay on your hands, and regular handwashing can help protect you from getting sick.
• Avoid touching your eyes, nose, and mouth with unwashed hands. Viruses that cause colds can enter your body this way and make you sick.
• Stay away from people who are sick. Sick people can spread viruses that cause the common cold through close contact with others.
• Disinfect frequently touched surfaces, including objects such as toys and doorknobs.

A change in season can brighten your days with vibrant new colors. But blooming flowers and falling leaves can usher in more than beautiful backdrops. Airborne substances that irritate your nose can blow in with the weather. When sneezing, itchy eyes, or a runny nose suddenly appears, allergies may be to blame.

Allergies arise when the body’s immune system overreacts to substances, called allergens, that are normally harmless. When a person with allergies breathes in allergens—such as pollen, mold, pet dander, or dust mites—the resulting allergic reactions in the nose are called allergic rhinitis, or hay fever.

Allergy is one of the most common long-term health conditions. “Over the past several decades, the prevalence of allergies has been increasing,” says Dr. Paivi Salo, an allergy expert at NIH. “Currently, airborne allergies affect approximately 10-30% of adults and 40% of children.”

Avoiding your allergy triggers is the best way to control your symptoms. But triggers aren’t always easy to identify. Notice when and where your symptoms occur. This can help you figure out the cause.

“Most people with allergies are sensitive to more than one allergen,” Salo explains. “Grass, weed, and tree pollens are the most common causes of outdoor allergies.” Pollen is often the source if your symptoms are seasonal. Indoor allergens usually trigger symptoms that last all year.

If your symptoms become persistent and bothersome, visit your family physician or an allergist. They can test for allergy sensitivities by using a skin or blood test. The test results, along with a medical exam and information about when and where your symptoms occur, will help your doctor determine the cause.

Even when you know your triggers, avoiding allergens can be difficult. When pollen counts are high, stay inside with the windows closed and use the air conditioning. Avoid bringing pollen indoors. “If you go outside, wash your hair and clothing,” Salo says. Pets can also bring in pollen, so clean them too.

For indoor allergens, keep humidity levels low in the home to keep dust mites and mold under control. Avoid upholstered furniture and carpets because they harbor allergens. Wash your bedding in hot water, and vacuum the floors once a week.

Allergies run in families. Your children’s chances of developing allergies are higher if you have them. While there’s no “magic bullet” to prevent allergies, experts recommend breast feeding early in life. “Breast milk is the least likely to trigger allergic reactions, it’s easy to digest, and it strengthens an infant’s immune system,” Salo says.

Sometimes, avoiding allergens isn’t possible or isn’t enough. Untreated allergies are associated with chronic conditions like sinus infections and asthma. Over-the-counter antihistamines, nasal sprays, and decongestants can often ease mild symptoms. Prescription medications and allergy shots are sometimes needed for more severe allergies. Talk with your doctor about treatment options.

Allergy relief can help clear up more than just itchy, watery eyes. It can allow you to breathe easy again and brighten your outlook on seasonal changes.

Allergy Symptoms

• Runny or stuffy nose
• Sneezing
• Itchy nose, eyes, ears, and mouth
• Red and watery eyes
• Swelling around the eyes
• Coughing
• Wheezing
• Chest tightness
• Shortness of breath

“Distinguishing COVID from flu can be difficult because the symptoms overlap so much,” explains Dr. Brooke Bozick, an NIH expert on respiratory diseases that affect the lungs.

Flu and COVID-19 are caused by different viruses that can be spread among people. Flu is caused by the influenza virus. COVID-19 is caused by SARS-CoV-2. Both can give you a fever, cough, headaches, and body aches.

Flu and COVID-19 also spread similarly. They’re transmitted by small particles that come from your nose and mouth when you sneeze, cough, sing, or talk, raising the possibility of infecting people who are nearby. Infected people may not have symptoms, but can still pass along either virus.

“Both influenza and COVID can be spread to other people before individuals develop symptoms,” notes Dr. Aubree Gordon, an infectious disease expert at the University of Michigan.

COVID-19 symptoms can take longer than flu symptoms to develop, she explains. Someone with flu usually has symptoms 1 to 4 days after being infected. A person with COVID-19 typically shows symptoms about 5 days after infection, although this can range from 2 to 14 days.

One telling sign of COVID-19 in some cases is loss of smell or taste. But because of other similar symptoms, there’s really only one way to be certain if you have COVID-19 or flu: Get tested.

“You can go and get a COVID test at many pharmacies, and your doctor can administer tests for flu,” Bozick says. COVID-19 tests are also available at many health centers. And you can buy testing kits approved for use at home.

Like flu and COVID-19, colds are also caused by viruses and can be passed to others.

Symptoms of a cold tend to be mild. You may have a runny nose, cough, congestion, and sore throat. But you won’t usually have the aches and fever that are common with COVID-19 and flu. Often, you’ll feel better in a couple of days.

There’s no cure for the common cold. Typical treatments include rest, fluids, and over-the-counter medicines. Some complementary treatments may help with cold symptoms, too. Taking honey may help with nighttime cough for children over 1 year old. Rinsing your nose and sinuses can help with congestion. You can use a neti pot or other nasal rinsing device. Be sure to only use water that’s been properly processed, such as distilled or boiled water, not tap water. Nasal rinses can bring relief for both cold and allergies.

Allergies can cause a runny nose and sneezing. But they’re not contagious. If your eyes, nose, or ears itch, that also could be an allergy.

Exposure to things like dust, pets, and tree or grass pollen can trigger allergies, which are caused by the immune system overreacting.

Allergy symptoms tend to stop when you’re no longer exposed to the cause. Unless you have asthma, allergies typically do not cause breathing problems. Allergies can be treated with drugs like antihistamines, decongestants, and nasal steroids.

Winter is the prime cold and flu season. You’re more likely to be indoors and closer to others when it’s colder outside. Weather also plays a role in the spread of viruses.

“Cold and flu viruses survive better and are more transmissible if it’s cooler and if there’s lower humidity,” Gordon explains.

Experts are concerned that flu and COVID-19 cases may increase and overlap in the winter. Flu cases usually start to increase around October and peak between December and February. Being infected with flu and SARS-CoV-2 at the same time is possible, as is showing symptoms of both.

If you’re sick with the flu, your doctor may prescribe antiviral drugs. Such drugs can make your flu milder and shorten the time you are sick. They work best if they’re used early in your illness.

The FDA has also approved one antiviral drug, called remdesivir, to treat COVID-19. Other treatments are in development and under review. No complementary approaches have been shown to be helpful for fighting off flu or COVID-19.

Fortunately, strategies to prevent the spread of COVID-19 also prevent the spread of flu and cold. “Measures like masking and social distancing work for other respiratory viruses, as well as COVID-19,” says Dr. Chip Walter, who studies vaccine development at Duke University.

There’s another really important way to fight viruses. “Get your flu shot and COVID-19 vaccine,” Walter advises. They are safe and effective ways to protect yourself and those around you.

Don’t forget to vaccinate your children, too. That is the best way to protect their health. COVID-19 vaccines are now recommended for everyone age 5 years and older.

Flu vaccines are recommended for everyone 6 months and older. Flu vaccines are designed to protect against the four types of flu viruses that scientists expect to circulate that year.

Researchers like Walter and others are working to develop flu vaccines that last longer and offer broader protection against many flu strains.

Masks continue to be an important tool for stopping the spread of respiratory viruses, such as COVID-19. “With the pandemic still ongoing, it’s going to be really important that people wear masks,” Gordon says. Try to avoid crowded indoor situations when possible, too.

Stay Well this Winter

Tips to help you avoid getting sick:

• Get a flu shot and COVID-19 vaccine.
• Avoid close contact with people who are sick. If you’re sick, limit contact with others to keep from infecting them.
• Cover coughs and sneezes. Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• Wash your hands often with soap and water. Scrub your hands for at least 20 seconds. Not sure how long that is? Hum Happy Birthday twice. Be sure to lather the backs of your hands, between your fingers, and under your nails.
• Use hand sanitizer if soap and water are not available.
• Avoid touching your eyes, nose, and mouth. Germs spread this way.
• Clean and disinfect surfaces and objects that may be contaminated with viruses.