Flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. Most people who get influenza will recover within two weeks – and sometimes in as little as a few days – but others will develop life-threatening complications (such as pneumonia) as a result of the flu.

Anyone can get the flu – even healthy people – and serious complications from influenza can happen at any age. People age 65 and older, people of any age with chronic medical conditions (such as asthma, diabetes, or heart disease), pregnant women and young children are more likely to get complications from influenza.

The main way that influenza viruses are spread is from person to person in respiratory droplets of coughs and sneezes (called “droplet spread”). This can happen when droplets from the cough or sneeze of an infected person are propelled through the air and deposited in the mouth or nose of people nearby. Influenza viruses may also be spread when a person touches respiratory droplets on another person or object and then touches their own mouth, nose or eyes (or someone else’s) before washing their hands.

The flu spreads in similar ways to COVID-19. Learn more about the flu and COVID-19 here.

Flu symptoms start one to four days after the virus enters the body, meaning you may be able to pass on the flu to someone else before you know you’re sick. Most healthy adults may be able to infect others beginning one day before symptoms develop and up to seven days after becoming sick. Children may pass on the virus for longer than ten days.

Additionally, some people can be infected with the flu virus but have no symptoms. During this time, those people can still spread the virus to others.

The CDC recommends the following three actions:

• Get a flu vaccine.
• Practice every day preventative actions, such as regular hand washing.
• Take antiviral medication to treat flu if your doctor prescribes them.

Everyone 6 months or older should get a flu shot.

No. The flu shot does not, and cannot, cause flu illness, because it contains only inactivated (killed) viruses.

While a flu vaccine cannot give you flu illness, there are different side effects that may be associated with getting a flu shot or a nasal spray flu vaccine. These side effects are mild and short-lasting, especially when compared to symptoms of bad case of flu.

According to the CDC, some minor side effects that may occur are:

• Soreness, redness, and/or swelling where the shot was given
• Headache (low grade)
• Fever
• Muscle aches
• Nausea
• Fatigue

Yes. It is safe to receive vaccinations for both flu and COVID-19 during the same visit. There is no need to wait to receive these vaccinations on different days.

Yes. If you are pregnant, or are considering pregnancy, please get a flu vaccine to reduce the risk of illness in you and your baby. As noted by the CDC, flu shots are safe for you and your baby, and you can get your flu vaccination at any time while pregnant, during any trimester.

For more information, speak with your obstetrician or primary care provider and read the CDC’s Flu & Pregnancy guidance.

Although you may be taking precautions to avoid COVID-19 that may also reduce your risk of getting the flu, it is still recommended that you get a flu vaccine. While COVID-19 appears to be more deadly than influenza, the flu is still serious and can require hospitalization.

Learn more about the flu and COVID-19 here.

Flu vaccines are also available at pharmacies and drug stores, as well as many local health department locations.

• Wash your hands often, with soap and water or an alcohol-based hand sanitizer.
• Cover your coughs and sneezes.
• Don’t touch your face.
• Stay away from people who are sick.
• Clean and disinfect your home, office or workspace often, focusing on surfaces you touch frequently, such as doorknobs, water faucets, refrigerator handles and telephones.
• Boost your immunity by exercising, eating healthy and balanced meals, staying hydrated, and getting plenty of rests.
• Wear a mask in public, to protect yourself from both the flu and COVID-19.

Some people are at high risk of developing serious complications if they get sick with flu-like symptoms:

Please note that many of the groups that are in high-risk categories for the flu are also at a higher risk of developing complications from COVID-19. Learn more about the flu and COVID-19 here, and speak to your health provider about how you can protect yourself against both illnesses.

• Children younger than 5 years, especially those under the age of 2
• Adults 65 and older
• Pregnant women (and women up to two weeks postpartum)
• People of any age with certain chronic medical conditions, such as asthma, diabetes, chronic kidney disease or heart disease
• People with weakened immune systems
• People with a BMI of 40 or higher

If you’re in a high-risk group, we recommend that you call your health care provider to discuss additional steps you may need to take to protect yourself against the flu and COVID-19.

According to the CDC, the flu often comes on suddenly, and often includes some or all of the following symptoms:

• Fever, or feeling feverish/chills
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headaches
• Fatigue or tiredness
• Vomiting and diarrhea (more common in children than adults)

If you think you’ve been exposed to someone with the flu or are starting to have flu-like symptoms, call your health care provider. Certain medications can help if you start taking them within the first 48 hours. Stay home from work or school – taking it easy could help you feel better sooner, and will also slow the spread of disease to others.

Please note that many flu symptoms are similar to those of COVID-19. See our symptom comparison chart here, and contact your health care provider to find out if diagnostic testing is necessary.

If your child is less than 3 months old, do not give them fever-reducing medicine. Seek medical advice from your pediatrician.

The following flu-like symptoms may be signs of complications:

• Difficulty breathing or shortness of breath
• Pain or pressure in the chest or abdomen
• Sudden dizziness
• Confusion
• Severe or persistent vomiting
• Symptoms returning after a period of improvement, with fever and worse cough

Contact your health care provider immediately, or go to the emergency room. Call 911 if necessary.

• Fast breathing or trouble breathing
• Bluish color in skin or lips
• Not drinking enough fluids
• Not waking up, or not interacting with others
• Being so irritable that the child doesn’t want to be held
• Symptoms returning after a period of improvement, with fever and worse cough
• Fever with a rash

Contact the child’s health care provider immediately or go to the emergency room. Call 911 if necessary. In addition to the warning signs outlined above, get medical help right away for any infant who:

• Is unable to eat
• Has trouble breathing
• Has no tears when crying
• Has significantly fewer wet diapers than normal

If you have the flu, or begin to experience flu-like symptoms, stay home from work or school. Consult your doctor early on regarding treatment. If you need to leave the house while you are sick, always wear a surgical mask. Watch for warning signs of complications.

Flu treatment can vary, so contact your doctor as soon as you begin to experience symptoms. In general, you will want to get lots of rest, drink plenty of liquids, and avoid using alcohol and tobacco. There are also over-the-counter (OTC) medications, such as aspirin, that can relieve flu symptoms. You should never give aspirin to children or teenagers who have flu-like symptoms, particularly fever.

Guidelines for preventing the spread of the flu virus are very similar to those for stopping the spread of COVID-19. Some of the top ways to prevent the spread off illness include:

• Thoroughly wash linens, eating utensils and dishes belonging to those who are sick before someone else uses them.
• Keep frequently touched surfaces (such as bedside tables, surfaces in the bathroom and toys for children) clean by wiping them down with a household disinfectant, following the directions on the product label.
• Those sick with the flu should try to stay in one part of the house, with the door shut, if possible, and ideally use a separate bathroom from those who are not ill.
• Caregivers should wear a mask when within six feet of the infected person. The person experiencing symptoms should also wear a mask if they need to interact with other members of the household.
• Keep a window open to help ventilate the home, if weather permits.
• Limit the number of people in the home – loved ones should call, not visit.

If you or a member of your household gets the flu, it’s best to stay home as much as possible. To avoid trips to the store, prepare your home for an unexpected illness by storing a two-week supply of water, food and household supplies. This preparation can also be useful if you contract COVID-19 or in case of emergencies, such as power outages and disasters. These supplies might include:

• Shelf-stable food: canned meats and fish, fruits, vegetables, beans and soups; protein bars; dried fruit, nuts and peanut butter; dry cereal or granola; crackers; juices, bottled water and fluids with electrolytes, such as Pedialyte or Gatorade; canned or jarred baby food and / or formula; pet food
• Medical supplies: a thermometer; anti-fever medications such as acetaminophen and ibuprofen; anti-diarrheal medications; any prescribed medications and glucose or blood pressure monitoring equipment
• Cleaning supplies: soap and water, alcohol-based hand sanitizer, garbage bags, household disinfectant
• Household supplies: personal hygiene items such as tissues, toilet paper and diapers; a manual can opener; a portable radio; a flashlight and batteries

The flu and the common cold are both respiratory illnesses, but they are caused by different viruses. They have similar flu-like symptoms, but colds are usually milder than the flu. Unlike the flu, colds typically do not result in serious health problems, such as pneumonia and bacterial infections, or hospitalization.

If you have a temperature under 100°F (37.8°C), with a cough, sore throat, runny nose and / or stuffy nose, you probably have a cold.

In general, flu and COVID-19 symptoms are more severe than those of the common cold. You may have the flu or COVID-19 if you experience fever, body aches, headache, difficulty breathing, extreme tiredness and a cough.

The best way to determine whether you have a cold, the flu, or COVID-19 is to speak to your health care provider, who can give you a diagnosis and advise you on the proper course of treatment.

See our symptom comparison chart to help you determine if your symptoms are those of a cold, the flu or COVID-19.