What’s the difference between a cold and the flu?

The common cold and the flu may seem similar at first. They’re both respiratory illnesses and can cause similar symptoms. But different viruses cause these two conditions.

Your symptoms can help you tell the difference between them.

Both a cold and the flu share a few common symptoms. People with either illness often experience:

runny or stuffy nose
sneezing
body aches
general fatigue
As a rule, flu symptoms are more severe than cold symptoms.

Another distinct difference between the two is how serious they are. Colds rarely cause other health conditions or problems. But the flu can lead to:

sinusitis
ear infections
pneumonia
sepsis
If your symptoms are severe, you may want to confirm either a cold or flu diagnosis. Your doctor will run tests that can help determine what’s behind your symptoms.

During the COVID-19 epidemic, call ahead for the protocol on visiting a doctor in person or having a online visit.

Cold and flu symptoms should also be treated with care due to their overlap with COVID-19 symptoms.

If your doctor diagnoses a cold, you’ll only need to treat your symptoms until the virus has run its course. These treatments can include:

using over-the-counter (OTC) cold medications
staying hydrated
getting plenty of rest
For the flu, taking flu medicine early in the virus’ cycle may help reduce severity of the illness and shorten the time that you’re sick. Rest and hydration are also beneficial for people with the flu.

Much like the common cold, the flu often just needs time to work its way through your body.

What’s the difference between the flu and COVID-19?
The symptoms of COVID-19, the flu, and allergies have some overlap, but are often different. The main symptoms of COVID-19 are:

tiredness
fever
cough
shortness of breath
Sneezing is not typical.

Flu symptoms are similar to COVID-19 including fever and body aches. But you may not find shortness of breath as a symptom with the flu.

Allergy symptoms are usually more chronic and include sneezing, coughing, and wheezing.

What are the symptoms of the flu?
Here are some of the common symptoms of the flu:

Fever
The flu almost always causes an increase in your body temperature. This is also known as a fever.

Most flu-related fevers range from a low-grade fever around 100°F (37.8°C) to as high as 104°F (40°C).

Although alarming, it’s not uncommon for young children to have higher fevers than adults. If you suspect your child has the flu, see their doctor.

You may feel “feverish” when you have an elevated temperature. Signs include chills, sweats, or being cold despite your body’s high temperature. Most fevers last for less than 1 week, usually around 3 to 4 days.

Cough
A dry, persistent cough is common with the flu. The cough may worsen, becoming uncomfortable and painful.

You may sometimes experience shortness of breath or chest discomfort during this time. Many flu-related coughs can last for about 2 weeks.

Muscle aches
Flu-related muscle pains are most common in your neck, back, arms, and legs. They can often be severe, making it difficult to move even when trying to perform basic tasks.

Headache
Your first symptom of the flu may be a severe headache. Sometimes symptoms, including light and sound sensitivity, go along with your headache.

Fatigue
Feeling tired is a not-so-obvious symptom of the flu. Feeling generally unwell can be a sign of many conditions. These feelings of tiredness and fatigue may come on fast and be difficult to overcome.

Learn more about how to recognize the symptoms of the flu.

Flu shot: Know the facts
Influenza is a serious virus that leads to many illnesses each year. You don’t have to be young or have a compromised immune system to get gravely ill from the flu. Healthy people can get sick from the flu and spread it to friends and family.

In some cases, the flu can even be deadly. Flu-related deaths are most common in people ages 65 and older, but can be seen in children and young adults.

The best and most efficient way to avoid the flu and prevent spreading it is to get a flu vaccination.

The flu vaccine is available in the following forms:

injectable shot
high-dose injectable shot (for those over age 65)
intradermal shot
nasal spray
The more people that get vaccinated against the flu, the less the flu can spread. It also helps with herd immunity, helping to protect those who can’t get the vaccine for medical reasons.

Vaccination can also help lessen the severity of the illness if you do end up getting the flu.

How does the flu shot work?
To make the vaccine, scientists select the strains of the flu virus that research suggests will be the most common in the coming flu season. Millions of vaccines with those strains are produced and distributed.

Once you receive the vaccine, your body begins producing antibodies against those strains of the virus. These antibodies provide protection against the virus.

If you come into contact with the flu virus at a later point, you can avoid contracting it.

You may get sick if you end up coming into contact with a different strain of the virus. But the symptoms will be less severe because you had the vaccination.

Who should get the flu shot?
Doctors recommend that everyone over the age of 6 monthsTrusted Source receive the flu vaccine. This is especially true for people in high-risk categoriesTrusted Source like:

pregnant women
children under age 5
people ages 18 and under who receive aspirin therapy
people over age 65
people whose body mass index is 40 or higher
anyone working or living in a nursing home or chronic care facility
caregivers to any of the above
American Indians or Alaska Natives
anyone with chronic medical conditions
Most doctors also recommend that everyone gets their flu vaccine by the end of October. This way your body has time to develop the right antibodies before flu season kicks into gear.

Even if you don’t get the flu shot by October 31, it’s not too late. Even if it’s well into flu season, it’s always helpful to get the flu shot.

It takes about 2 weeks for antibodies to develop against the flu after vaccination.

The Centers for Disease Control and Prevention (CDC) believes that both flu and the new coronavirus, COVID-19, will be spreading this year. Because of this, the vaccine will be more important than ever.

Learn more about the importance of the flu shot.

Side effects of the flu shot
Many people report avoiding the flu vaccine each year for fear that it will make them sick. It’s important to understand that the flu vaccine can’t cause you to develop the flu.

You aren’t going to become sick because you received the vaccine. Flu vaccines contain dead flu virus. These strains aren’t strong enough to cause an illness.

Like other shots, you may experience some side effects from the flu shot. These side effects are often mild and only last a short period of time. The side effects of a shot outweigh the possible symptoms of developing the flu later.

The most common side effects of the flu shot include:

soreness around the injection site
low-grade fever in the days immediately following the injection
mild aches and stiffness
Any side effects that do occur often last only a day or two. Many people won’t experience any side effects at all.

On rare occasions, some people may have a serious allergic reaction to the vaccination. If you’ve had an allergic reaction to any vaccine or medication before, talk with your doctor.

Learn more about the possible side effects of the flu shot.

How long does the flu last?
Most people recover from the flu in about a week. But it may take several more days for you to feel back to your usual self. It’s not uncommon to feel tired for several days after your flu symptoms have subsided.

It’s important to stay home from school or work until you’ve been free of fever for at least 24 hours (and that’s without taking fever-reducing medications).

If you have the flu, it can be passed to another person a day before your symptoms appear and up to 5–7 days afterward.

If you have any cold or flu symptoms during the COVID-19 pandemic, you must isolate yourself while getting tested and continue to practice good hygiene such as:

washing your hands
disinfecting high-touch areas
wearing a face covering
avoiding contact with others
Treatment options for the flu
Most cases of the flu are mild enough that you can treat yourself at home without prescription medications.

It’s important you stay home and avoid contact with other people when you first notice flu symptoms.

You should also:

Drink plenty of fluids. This includes water, soup, and low-sugar flavored drinks.
Treat symptoms such as headache and fever with OTC medications.
Wash your hands to prevent spreading the virus to other surfaces or to other people in your house.
Cover your coughs and sneezes with tissues. Immediately dispose of those tissues.
Wear a face covering when in public.
If symptoms become worse, call your doctor. They may prescribe an antiviral medication. The sooner you take this medicine, the more effective it is. You should start treatment within 48 hours from when your symptoms start.

Contact your doctor as soon as symptoms appear if you’re at high risk for flu-related complications.

High-risk groups include:

people with weakened immune systems
women who are pregnant or up to 2 weeks postpartum
people who are at least 65 years old
children under 5 years old (in particular, those under age 2)
people who live in chronic care facilities or nursing homes
people who have chronic conditions, such as heart or lung disease
people who are of Native American (American Indian or Alaska Native) descent
Your doctor may test for the flu virus right away. They may also prescribe an antiviral medication to prevent complications.

When is flu season?
In the United States, the main flu season stretches from October to March. Cases of the flu peak between December and February, according to the CDCTrusted Source. But you can get flu at any time of the year.

You’re more likely to get sick during the fall and winter months. This is because you’re spending more time in close quarters with other people and are also exposed to lots of different illnesses.

You’re more likely to catch the flu if you already have a different virus. This is because other infections can weaken your immune system and make you more vulnerable to new ones.

Remedies for flu symptoms
Having the flu is no fun. But remedies for flu symptoms are available, and many of them provide great relief.

Keep these treatments in mind if you have the flu:

Pain relievers. Analgesics like acetaminophen and ibuprofen are often recommended to help ease symptoms. These include muscle aches and pains, headache, and fever.
Decongestants. This type of medication can help relieve nasal congestion and pressure in your sinuses and ears. Each type of decongestant can cause some side effects, so be sure to read labels to find the one that’s best for you.
Expectorants. This type of medication helps loosen thick sinus secretions that make your head feel clogged and cause coughing.
Cough suppressants. Coughing is a common flu symptom, and some medications can help relieve it. If you don’t want to take medication, some cough drops use honey and lemon to ease a sore throat and cough.
Warning: Children and teens should never take aspirin for any illness. This is because of the risk of a rare but fatal condition called Reye’s syndrome.

Be careful not to mix medications. Using unnecessary medication could cause unwanted side effects. It’s best to take medicines that apply to your predominant symptoms.

In the meantime, get plenty of rest. Your body is fighting hard against the influenza virus, so you need to give it plenty of downtime. Call in sick, stay at home, and get better. Don’t go to work or school with a fever.

You should also drink plenty of fluids. Water, low-sugar sports drinks, and soup can help you stay hydrated. Warm liquids like soup and tea have the added benefit of helping ease pain from a sore throat.

Flu symptoms in adults
Flu-related fever appears in adults and can be severe. For many adults, a sudden high fever is the earliest symptom of the flu. It can also be a sign of COVID-19.

Adults rarely spike a fever unless they have a serious infection. The flu virus causes an abrupt high temperature that’s greater than 100°F (37.8°C).

Other viral infections, like a cold, may cause low-grade fevers.

Beyond this, children and adults share many of the same symptoms. Some people may experience one or several symptoms more than another person. Each person will be different.

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What’s the incubation period for the flu?
The typical incubation period for the flu is 1 to 4 days. Incubation refers to the period during which the virus is in your body and developing.

During this time, you may not show any symptoms of the virus. That doesn’t mean that you aren’t able to pass it to someone else. Many people are capable of transmitting the virus to others a day before symptoms appear.

The millions of tiny droplets that are produced when we sneeze, cough, or talk, spread the flu virus. These droplets enter your body through your nose, mouth, or eyes.

You can also get the flu by touching a surface that has the virus on it and then touching your nose, mouth, or eyes.

Is there such a thing as the 24-hour flu?
The “24-hour flu” (or gastroenteritis) is a common stomach infection that has nothing to do with influenza, despite sharing a name. The 24-hour stomach flu is caused by a genus of viruses called norovirus.

The symptoms of norovirus include:

diarrhea
nausea
vomiting
stomach cramping
These symptoms occur in the gastrointestinal system. That’s why the 24-hour flu is sometimes called a “stomach flu.” Although it’s called the “24-hour flu,” you may be ill for up to 3 days.

The symptoms of the 24-hour flu and influenza (the flu) are different. The flu is a respiratory illness. Respiratory system symptoms of the flu include:

coughing
headaches
fever
runny nose
body aches
Some people with influenza may experience nausea and vomiting while they’re sick. But these symptoms aren’t as common in adults.

Is the flu contagious?
If you have the flu, you’re contagious — meaning you can pass the flu to others.

Many people can spread the virus as early as a day before they show symptoms. In other words, you may be transmitting the virus before you even realize that you’re sick.

You may still be spreading the virus 5 to 7 days after your symptoms appear. Young children are often able to pass the virus for more than 7 days after symptoms first appear.

People who have a weak immune system may experience the virus symptoms longer, too.

If you have the flu or any flu symptoms, stay home. Do your part to prevent the spread of the virus to other people. If you’re diagnosed, alert anyone you came into contact with on the day before your symptoms appeared.

Learn more about whether the flu is contagious.

What is the flu?
Influenza (the flu) is a common, infectious virus spread by droplets that enter another person’s body. From there, the virus takes hold and begins to develop.

Each year, the flu spreads across the United States. A 2018 CDC studyTrusted Source found that the flu affects between 3–11 percent of U.S. people each year. This accounts for people who have symptoms.

Winter is the flu’s primary season, with a peak in February. But you can get the flu any time of the year.

Many strains of the flu exist. Doctors and researchers determine which strains of the virus will be most common each year.

Those strains are then used to produce vaccines. A flu vaccine is one of the easiest and most effective ways to prevent the flu.

Is there medication for the flu?
Medications called antiviral drugs can treat the flu. You can’t buy these medications over the counter at a pharmacy. They’re available by prescription only, and you must visit a doctor or healthcare provider to receive a prescription.

Antiviral medications used to treat the flu can help ease the symptoms. They can also shorten the length of the flu by a day or two.

Taking antiviral medications may help if you get the flu, but these medications also have side effects. Talk to your doctor to understand the risks.

Research suggests antiviral medications work best if you take them within 48 hours of having symptoms. If you miss that window, don’t worry. You may still see a benefit from taking the medicine later.

This is especially true if you’re at high risk or are ill. Taking antiviral medications may help protect you against flu complications. These include pneumonia and other infections.

Early symptoms of the flu
Symptoms of the flu appear quickly. This sudden onset of symptoms is often the flu’s first hallmark. With similar illnesses, such as a cold, it can take several days for symptoms to emerge.

Another common early symptom of the flu is the breadth of pain. People with the flu report feeling uncomfortable all over their body as an early symptom.

You may feel as if you’ve been “hit by a truck.” Getting out of bed may prove to be difficult and slow going. This feeling may be an early symptom of the flu.

After this, other symptoms of the flu may begin appearing, making it obvious you have the virus.

Learn more about early flu symptoms.

Are there natural flu remedies?
If left untreated, a typical case of the flu often goes away in about 1 week. During that time, you have several treatment options for making symptoms easier to handle.

Prescription antiviral medicines can reduce the severity of the infection. They can also shorten its duration. Some OTC treatments can ease the symptoms as well.

Some natural flu remedies may be helpful for easing symptoms. For instance, for a sore throat or cough, some options include:

honey
warm tea
warm soup
Of course, rest is also an important part of recovering from the flu, or any other type of virus.

Your body is fighting hard to get well. It’s wise for you to stop, rest, and get more sleep so your immune system can fight back against the virus.

Options for over-the-counter (OTC) flu medicine
OTC medicines can help relieve symptoms of the flu, but they won’t treat it. If you have the flu and are looking for symptom relief, consider these medicines:

Decongestants. Nasal decongestants help break up mucus in your sinuses. This allows you to blow your nose. Decongestants come in several forms including nasal decongestants that are inhaled and oral (pill) decongestants.
Cough suppressants. Coughing, especially at night, is a common flu symptom. OTC cough medicines can ease or suppress your cough reflex. Cough drops or lozenges can soothe a sore throat and suppress coughing.
Expectorants. This type of medication may help you cough up phlegm if you have a lot of mucus or congestion in your chest.
OTC “flu medicines” like NyQuil often contain several of these types of drugs in one pill.

If you take one of these combination medications, avoid taking other medicine with it. This ensures that you don’t take too much of any one type of medicine.

What causes the flu?
The flu is a virus that’s spread in several ways. First, you can contract the virus from a person near you who has the flu and sneezes, coughs, or talks.

The virus can also live on inanimate objects for 2 to 8 hours. If someone with the virus touched a common surface, like a door handle or a keyboard, and you touch the same surface, you could get the virus.

Once you have the virus on your hand, it can enter your body if you touch your mouth, eyes, or nose.

You can get a vaccine against the flu. An annual flu vaccine helps your body prepare for exposure to the virus. But flu viruses are morphing and changing. That’s why you need the flu shot every year, and especially while COVID-19 is still active.

A flu shot helps you by activating your immune system to make antibodies against particular strains of influenza. Antibodies are what prevent infections.

It’s possible to get the flu after receiving the flu shot if you come into contact with other strains of the virus. Even then, it’s likely your symptoms will be much less severe than if you hadn’t had the vaccine at all.

This is because different strains of influenza share common elements (called cross-protection), which means that the flu vaccine is able to work against them, too.

Learn more about what causes the flu.

Where can I get a flu shot?
Most doctors’ offices carry the vaccine. You may also get the vaccine at:

pharmacies
walk-in medical clinics
county or city health departments
Some employers and schools also offer flu shot clinics on site, though many are closed due to the COVID-19 pandemic. Those that are open will begin promoting flu vaccines as flu season approaches. Some even offer incentives such as coupons to encourage you to receive your vaccine.

If you can’t find a flu shot provider, use a flu shot locator like the Vaccine Finder. This website list businesses, phone numbers, and hours of operation.

Flu shot for kids: What you should know
Each year, hundreds of thousands of children get sick from the flu. Some of these illnesses are severe and require hospitalization. Some even result in death.

Children who get the flu are often at a higher risk than adults who get sick from the flu. For example, children under age 5 are more likely to need medical treatment for the flu.

Severe complications from influenza are most common in children under 2 years old. If your child has a chronic medical condition, like asthma or diabetes, the flu may be worse.

See your doctor right away if your child has been exposed to the flu or shows flu symptoms. Call ahead for the protocol around COVID-19 prevention.

The best way to protect your children against the flu is with a flu vaccine. Vaccinate children each year.

Doctors recommend flu vaccines for children starting at 6 months old.

Some children between ages 6 months and 8 years may need two doses for protection against the virus. If your child is receiving a vaccine for the first time, they will likely need two doses.

If your child only received one dose in the flu season prior, they may need two doses this flu season. Ask your child’s doctor how many doses your child needs.

Children under 6 months of age are too young for a flu vaccine. To protect them, make sure the people around them get vaccinated. This includes family members and care providers.

Last medically reviewed on August 30, 2020

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Medically reviewed by Joseph Vinetz, MD — Written by Kimberly Holland — Updated on August 31, 2020
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