Flu-Like Symptoms

What are flu-like symptoms?

“Flu-like symptoms” is a term people use to describe how you typically feel when you have the flu (influenza). So, in a sense, they’re the same as flu symptoms. But you can have flu-like symptoms without actually having the flu. That’s why the “like” is so important. These are symptoms people associate with the flu, but they can occur for lots of different reasons (described further below).

When you hear someone say “flu-like symptoms,” they mean:

• Fever.
• Chills.
• Body aches.
• Cough.
• Headache.
• Sore throat.
• Runny nose.
• Stuffy nose.
• Feeling very tired.
• Diarrhea or vomiting (more likely in kids than adults).
• Nausea.

You might not have all of these symptoms when you have the flu, but you’ll likely have several of them. Similarly, you might have several of these symptoms without having the flu. For example, flu-like symptoms are common with other seasonal viruses like RSV or COVID-19. They can also occur for many other reasons.

Learning the many possible causes of flu-like symptoms can help you identify why you might be feeling sick and when to seek medical care.

What are the possible causes of flu-like symptoms?

Bacterial and viral infections are the most common causes of flu-like symptoms among people in the U.S. Many of these infections, like respiratory syncytial virus (RSV) or the common cold, spread from person to person. But some infections spread from animals to humans. There are also many other causes of flu-like symptoms. For example, these symptoms can occur as treatment side effects or signs of complications after surgery.

Viral infections

Besides the flu, viral infections that can cause flu-like symptoms include:

• Acute hepatitis C.
• Adenovirus.
• Common cold.
• COVID-19.
• Fifth disease.
• Hand, foot and mouth disease.
• HIV (initial infection).
• Mononucleosis, commonly called “mono”.
• Mpox.
• RSV.
• Viral gastroenteritis.
• Viral meningitis.
• Viral pneumonia.

Bacterial infections

Bacterial infections that can cause flu-like symptoms include:

• Acute bacterial prostatitis.
• Acute mastoiditis.
• Bacterial gastroenteritis.
• Bacterial mastitis.
• Bacterial meningitis.
• Bacterial pneumonia.
• Bacterial sinus infection (sinusitis).
• Cellulitis.
• Pelvic inflammatory disease (PID).
• Strep throat.
• Syphilis (second stage).
• Urinary tract infection (UTI).
• Toxic shock syndrome (a complication of some bacterial infections).

Infections spread by animals

Animals (including bugs like ticks) sometimes carry germs or parasites that spread to humans and cause infection. You might get such an infection through a bite (like a mosquito bite) or by touching an animal’s pee or other bodily fluids. Or you might get it through contact with contaminated water, food or soil.

Some of these infections can cause flu-like symptoms. Examples include:

• Anaplasmosis.
• Avian influenza, commonly called “bird flu.”
• Babesiosis.
• Campylobacter infection (Campylobacteriosis).
• Cat scratch disease.
• E. coli infection.
• Ehrlichiosis.
• Heartland virus disease.
• Histoplasmosis.
• Jamestown Canyon virus.
• Leptospirosis.
• Listeriosis.
• Lyme disease.
• Rabies.
• Rocky Mountain spotted fever.
• Roundworm.
• Salmonellosis, commonly called “salmonella.”
• Toxoplasmosis.
• Valley fever.
• West Nile virus.
• Yellow fever.
• Zika virus.

Treatment-related causes

Sometimes, flu-like symptoms are known side effects of treatment for a certain medical condition, like cancer. Other times, they happen when treatment doesn’t quite go as planned. Generally, in relation to treatment, flu-like symptoms may be a:

• Side effect of a treatment like Botox injections, immunotherapy, chemotherapy or radiation therapy.
• Sign of antidepressant discontinuation syndrome (when you suddenly stop taking antidepressants after taking them for at least six weeks).
• Sign of a complication, like infection, after a surgery or procedure.
• Sign of organ transplant rejection, like heart transplant rejection or kidney transplant rejection.

What’s causing my symptoms?

When trying to figure out the cause of your symptoms, it can help to think about any recent experiences or exposures that might be responsible. For example, you might consider whether you’ve been:

• In close contact with someone who’s sick.
• Traveling or otherwise in a situation where germs could easily spread.
• In wooded or grassy areas with ticks or mosquitos.
• Taking a medication or undergoing a treatment.

Thinking about these factors can help you identify possible causes of your symptoms and rule out others that are less likely. You should also share this information with your healthcare provider if you call or schedule an appointment to discuss your symptoms.

How are flu-like symptoms treated?

Treatment varies according to the cause. Your healthcare provider will tailor treatment to your specific needs. Common treatments for the causes of flu-like symptoms include:

• Self-care at home, including getting plenty of rest and drinking enough fluids.
• Over-the-counter (OTC) medications, like acetaminophen or NSAIDs (nonsteroidal anti-inflammatory drugs).
• Prescription medications, like antibiotics, antivirals, antifungals and antiparasitics. 
• IV fluids or other treatments at a hospital.

Can flu-like symptoms be prevented?

It’s not always possible to prevent infections or other causes of flu-like symptoms. But there’s a lot you can do to lower your risk. Here are some tips:

• Wash your hands at appropriate times, like after using the bathroom and before you eat.
• Stay up to date on the vaccines your healthcare provider recommends, including those that protect you against the flu, COVID-19 and pneumonia.
• Avoid being around others who are sick.
• Use insect repellent to protect yourself against ticks, mosquitos and other bugs that can cause illness. It’s also a good idea to wear long sleeves and pants when hiking or spending time in wooded or grassy areas.
• Do research on which infectious diseases to watch for near home or away from home. Being aware of whether ticks, mosquitos or other animals carry them can help you narrow down what you might pick up. That can also help you recognize symptoms later.
• Practice good safety techniques when preparing and storing food to avoid becoming ill.
• Practice good environmental hygiene, like cleaning kitchen and bathroom surfaces well.
• Use personal protective equipment (PPE), such as a mask, if/when needed.

When should flu-like symptoms be treated by a healthcare provider?

Call a provider if you have flu-like symptoms and any of the following are true for you:

• Your symptoms don’t start to improve after seven to 10 days, or your fever lasts longer than three days (prolonged flu-like symptoms).
• Your symptoms suddenly get worse.
• You’re pregnant.
• You have an underlying condition that puts you at greater risk for severe illness from the flu.
• You’re recovering from a surgery or procedure.

When to go to the emergency room

Call 911 (or your local emergency service number) or go to your nearest ER if you have any of the following:

• A fever higher than 103 degrees Fahrenheit (40 degrees Celsius).
• Trouble breathing.
• Little or no pee when you go to the bathroom.
• Chest pain or stomach pain that doesn’t go away.
• Dizziness that doesn’t go away.
• Confusion.
• Severe muscle pain or weakness.
• Seizures.
• Bluish color to your lips, skin or nails (a sign of low levels of oxygen in your blood or tissues).
• Fever or cough that seems to improve but then gets worse.
• Any signs or symptoms of an existing medical condition getting worse.

Why am I feeling flu-like symptoms after exercise?

Physical activity can sometimes cause symptoms that mimic those of a cold or flu. Possible reasons include:

• Exercise-induced rhinitis (EIR). This is a form of vasomotor rhinitis where physical activity triggers inflammation of the tissues inside of your nose. EIR can lead to symptoms like a runny nose while you’re active or after you finish.
• Exercise-related cough. If you have exercise-induced asthma, you may cough soon after you start working out or right after you finish. You might also have other symptoms like wheezing, difficulty breathing or severe fatigue. Aside from asthma, there are other reasons why you might cough after physical activity. These include exposure to allergens (allergic rhinitis), pollutants and cold air while working out.
• Delayed-onset muscle soreness. This is muscle pain that starts a couple of days after an intense workout but goes away pretty quickly (usually within a few days). It can happen if you try a new type of physical activity or ramp up the intensity of your workouts. 
• Overreaching or overtraining. These are both examples of exercising too much. Overreaching is when you exercise too much within a short period of time. Your body isn’t ready for it, and you end up with muscle soreness that persists for at least two days. Overtraining is when you consistently push the limits when you work out. Fatigue is a common symptom. In some cases, overtraining leads to chronic colds, infections and other illnesses. 

Exercise should make you feel good. If you notice your workouts are leaving you drained, sore or otherwise under the weather, contact a healthcare provider. They’ll identify what’s causing your symptoms and help you find relief.

Can lack of sleep cause flu-like symptoms?

Lack of sleep (sleep deprivation) can cause some flu-like symptoms like fatigue and headaches. You may have other symptoms, too, like irritability and trouble focusing.

But if you’re sleep-deprived and experiencing flu-like symptoms, it’s possible you actually have the flu or another infection. That’s because, over time, lack of sleep can weaken your immune system and make you more likely to get sick. Working on your sleep hygiene can help you get more (and better quality) sleep so you can feel better and stay healthier.

What if I have flu-like symptoms during pregnancy?

If you have flu-like symptoms while pregnant, contact a healthcare provider right away. They’ll find the cause and make sure you get treatment, if necessary.

One possibility is that you have the flu or another virus. The flu is more dangerous for pregnant people compared to those who aren’t pregnant. It’s more likely to cause severe symptoms and hospitalization. Your provider may prescribe medications (like antivirals) or recommend other treatments.

But there are other possibilities, too, depending on your symptoms. Nausea and vomiting are common symptoms of morning sickness, which affects up to 70% of pregnant people during their first trimester. Morning sickness doesn’t cause other flu-like symptoms such as fever, chills or body aches.

Nausea and vomiting are also symptoms of preterm labor. This is when you go into labor before you’ve reached 37 weeks of pregnancy. In this case, you may also have other symptoms like contractions, cramping or leaking of fluid from your vagina. You need immediate medical care for preterm labor.

What if I have conjunctivitis and flu-like symptoms?

Conjunctivitis (pink eye) sometimes occurs as a symptom of viral infections, like the flu and COVID-19. So, if you have flu-like symptoms (like a fever and chills) as well as pink eye, it’s possible that the virus is causing your eye symptoms. It’s a good idea to call your healthcare provider and tell them what’s happening. They’ll let you know if you should come in for an appointment.

A note from Cleveland Clinic

Flu-like symptoms can zap all your energy and make you wish you could press a fast-forward button to get through the next week. Sadly, that’s not an option. But healthcare providers can recommend treatments to help ease symptoms and get you through the worst of it. When the cause is something more serious than a seasonal virus, your provider will help you understand the diagnosis and recommend appropriate treatment.