Influenza, or the flu, can be tricky to tell apart from the common cold. Both are respiratory illnesses caused by viruses, and they share many symptoms.
The common cold and the flu are both contagious, but cold symptoms tend to be milder and improve within 7 to 10 days.
While most people who get the flu recover in less than two weeks, the symptoms are usually more severe. The flu is also more likely to lead to serious complications, such as
pneumonia,
bronchitis, and sinus or
ear infections.
Because colds and the flu are caused by viruses rather than bacteria, antibiotics aren’t an effective treatment option for either infection.
Both the flu and colds affect the respiratory system, though flu symptoms are typically more severe.
“There are many different viruses that can cause a cold, but most of these viruses cause very similar cold symptoms,” says Aaron E. Glatt, MD, chief of infectious diseases at Mount Sinai South Nassau in Oceanside, New York.
While both infections can cause fever and body aches, the flu tends to cause higher-grade fevers and more severe body aches. Flu symptoms also tend to come on more suddenly than cold symptoms.
Influenza viruses cause the flu, but many distinct viruses (most commonly rhinoviruses) can cause a cold.
Flu and cold viruses are respiratory viruses which can be spread through the air, personal contact, and respiratory secretions. Encounters like handshakes, touching contaminated objects, and exposure to sneezes or coughs can lead to infection.
These viruses are around all year, but they tend to peak in fall and winter.
While anyone can catch a cold or the flu, there are certain populations at higher risk of severe illness, including:
- Children younger than 5
- People with weakened immune systems
- People with underlying medical conditions, such as asthma
Colds are typically diagnosed by evaluating symptoms and ruling out other conditions rather than through testing. Your doctor may also perform a physical exam.
If your symptoms are more severe, your doctor may order tests or X-rays to rule out certain illnesses, such as
strep throat or pneumonia.
To diagnose the flu, your doctor may use a rapid influenza diagnostic test. This involves testing nose or throat swab samples for influenza viral antigens (substances that cause your immune system to form antibodies).
Test results are usually ready in less than 15 minutes but are not always accurate. Other more reliable flu tests can be performed only in hospitals or specialized laboratories.
The duration of a cold or the flu varies depending on the virus involved and your immune system’s ability to fight off infection. That’s why the very young, older adults, and people with chronic illnesses are most susceptible to viral infections and possible complications.
“The best weapon we have is our own immune system,” says Donald W. Novey, MD, a family medicine physician at MultiCare Family Medicine in Poulsbo, Washington.
Good nutrition, adequate sleep and exercise, and low levels of stress can bolster the immune system. “A failure on any one of these four points can weaken the immune system and either prolong an existing cold or lead to more frequent ones,” Dr. Novey says.
Cold and flu symptoms typically subside within 7 to 10 days. The more severe flu symptoms tend to ease after a few days, but some symptoms, such as fatigue and
cough, can linger for weeks.
The flu can last anywhere from a few days to a few weeks.
There’s no cure for either the flu or the common cold, but many medications can help treat symptoms while your body fights the infection.
Over-the-counter options include:
- Throat lozenges or sprays
- Cough suppressants
- Saline drops or sprays
- Decongestants
- Pain relievers or fever reducers
Keep in mind that cold medicines and pain relievers can have side effects and pose health risks. Always check the product’s label for potential drug interactions and consult your doctor if you’re not sure if a drug is right for you.
Children and teenagers with flu-like symptoms should not take aspirin (Bayer) for pain or fever. This has been linked to the potentially life-threatening condition Reye’s syndrome.
Prescription antiviral drugs can be used to treat the flu, especially in patients at higher risk of complications (such as those with asthma, diabetes, or heart disease). If you start these drugs within two days of when your symptoms start, they may help shorten the time you’re sick, reduce complications, and lessen the severity of symptoms.
The U.S. Food and Drug Administration has approved four antiviral drugs: oseltamivir (Tamiflu), peramivir (Rapivab), zanamivir (Relenza), and baloxavir marboxil (Xofluza).
Unlike the common cold, the flu has a vaccine. While the vaccine doesn’t prevent you from getting the flu, it can help prevent complications and more severe cases of flu. The CDC recommends everyone 6 months and older get a flu vaccine every year (unless you’ve had a severe
allergic reaction to it in the past).
Practicing good hygiene and limiting exposure can help reduce the risk of catching both colds and the flu. Best practices include:
- Washing your hands regularly
- Avoid touching your eyes, face, or mouth
- Strengthening your immune system
- Staying home if you’re sick
- Wearing a mask in public places
The flu is more likely to cause severe symptoms, but both can lead to health complications. People with existing health conditions like asthma or those with compromised immune systems are at higher risk of developing complications.
If you experience any of the following symptoms, call your doctor right away:
- Difficulty breathing
- Chest pain or pressure
- Dizziness or confusion
- Severe muscle pain
- Seizures
- Severe weakness
Rachel Green
Rachel Davis
Derek Schulz
Sophia Martinez
Dr. Amara Okafor