Is the Flu Viral or Bacterial? Find Out More

By Craig Sorkin, DNP, APN
Medically reviewed checkmarkMedically reviewed
March 11, 2022

Some illnesses are caused by viruses, while others are caused by bacteria. Knowing which is the culprit for your current infection can help you better understand why your doctor recommends a specific treatment.

It is important to understand, that not receiving medications such as antibiotics, even if you have had antibiotics for similar infections in the past, is not a punishment or a lack of care or empathy, it is rather a complex equation where the provider is deciding which course of action is most suited for your current complaint. 

Your provider at K health will usually suggest for you to follow up in a couple days, especially if a virus is suspected, to reevaluate your symptoms and decide if any change to the established medical plan is required. 

In this article, we will explore:

  1. How contagious the flu is
  2. Common influenza symptoms 
  3. The differences between viral and bacterial infections
  4. Common treatments and remedies for the flu
  5. Danger signs and when you should see a doctor

How Contagious is the Flu?

Influenza is caused by a family of highly contagious viruses.

The flu is spread through droplets released when someone with an influenza infection coughs, sneezes, or talks.

These droplets hang in the air briefly, and you can inhale them and become infected.

The droplets also land on surfaces, and if you touch those surfaces and then touch your eyes, mouth, or nose without washing your hands, you may contract the flu.

People may spread the influenza virus for 1-2 days before they start to have symptoms and then 3-4 days after symptoms begin.

Younger children and people with compromised immune systems may stay contagious longer.

If you are exposed to the flu, you are not guaranteed to get it. Certain people have a higher risk of getting the flu or having a more severe illness: 

  • People with weakened immune systems
  • People older than age 65
  • People younger than age 5
  • People living in community homes
  • People who are pregnant
  • People who have chronic diseases or disorders (such as asthma, diabetes, heart disease, or kidney disease)
  • People who have a BMI greater than 40

Have the flu? Chat with a doctor through K Health.

get started

Flu Symptoms

The flu can cause common symptoms associated with respiratory illness.

The most common symptoms that may occur if you get the flu include:

  • Fever higher than 100.4ºF (38ºC)
  • Chills or sweating
  • Body aches and pains
  • Dry cough
  • Fatigue
  • Headache
  • Sore throat
  • Congestion or runny nose
  • Muscle weakness

Most adults do not experience gastrointestinal symptoms with influenza.

Children are more likely to experience vomiting, nausea, and/or diarrhea.

Most symptoms of the flu resolve within a week and may clear up sooner.

Differences Between a Virus and Bacteria

Viruses cause common illnesses like the cold or the flu. Bacteria are responsible for other common illnesses like strep throat.

There are three major differences between viruses and bacteria:

  • Bacteria can have positive benefits, like the “good” bacteria that exist in the microbiome and promote proper immune function. There are no positive benefits to viruses.
  • Bacteria can survive without a “host” and do not rely on humans to perpetuate. Viruses have to live in a host, like humans, to survive and to replicate. Viruses do this by hijacking cells and reprogramming them until the host’s immune system catches up and destroys the virus’s ability to replicate.
  • Thanks to the immune system, viral infections typically go away on their own. Many bacterial infections that cause problems require antibiotics to destroy the bacteria.

Flu vs. Common Cold

The flu and the common cold both tend to happen in the same seasons and have many similar symptoms. However, there are distinct differences between the two:

  • Symptom onset: Cold symptoms tend to come on slowly over a few days, while influenza is more sudden: You might feel fine one day and wake up the next day feeling sick or develop a sudden fever.
  • Fevers: While it is not impossible to have a fever with a cold, it is most common to have a fever with the flu and no elevated body temperature with the common cold.
  • Number of symptoms: Cold symptoms tend to be isolated to the head and may include a sore throat as well as nasal congestion and general congestion. Flu symptoms can include those, but are more likely to include a fever, coughing, and body aches and may not include congestion.
  • Viral causes: The flu is caused by influenza viruses, whereas the common cold is caused by seasonal coronaviruses, rhinoviruses, or parainfluenza viruses.
  • Tests: You can get a test at your doctor’s office to identify the strain of flu that you have. It is not possible to test for common cold viral strains. 
  • Length of illness: Colds tend to last for up to 14 days, but flu infections are often shorter, lasting 3-7 days.

Flu Treatments and Remedies

You can’t make the flu go away faster, but you can do things at home to feel better and make your symptoms less bothersome:

  • Get plenty of rest
  • Stay properly hydrated
  • Take over-the-counter pain medication and/or cold or flu medication
  • Diffuse essential oils or use vapor rub for congestion
  • Suck on cough drops or throat lozenges for throat pain or cough
  • Take warm baths or use hot compresses for achy joints and muscles
  • Vitamine C and Zinc taken within the first 48 hours of illness have been shown to reduce severity and duration of colds and flu illnesses

It’s also important to avoid things that might make you feel worse. Do not exercise intensely when you are sick. Avoid alcohol, cigarettes, and other substances. 

f you are nauseous or vomiting, eating a BRAT (bananas, rice, applesauce, toast) diet may help decrease stomach upset.

Lastly, while the flu shot is not a remedy, it is worth noting that getting a yearly flu shot helps decrease the chance of getting the flu or experiencing severe illness from it.

It can also help your body clear the infection faster since your immune system was already primed to fight it.

Have the flu? Chat with a doctor through K Health.

get started

When to See a Medical Provider

You can always consult a healthcare professional. While there are no antibiotics for the flu, there are antiviral medications that if taken within the first 48 hours of infection, can drastically help.

If you have the flu and do not feel better after a week or you start to feel worse, check in with your doctor. 

If your fever increases, you have trouble breathing, you cannot keep food or liquids down or you notice other concerning symptoms, contact your healthcare provider, visit urgent care, or seek treatment at an emergency room.

How K Health Can Help

Did you know you can get affordable primary care with the K Health app? Download K to check your symptoms, explore conditions and treatments, and if needed text with a doctor in minutes. K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data.

  • Flu Contagiousness
  • Flu Symptoms
  • Differences Between a Virus and Bacteria
  • Flu vs Common Cold
  • Flu Treatments and Remedies
  • When to See a Doctor
  • How K Health Can Help

Frequently Asked Questions

Is the flu considered viral?
Yes, the flu is a viral infection. Influenza is a virus that has several strains. Most flu infections are caused by influenza A or influenza B.
Is the flu and Covid a virus?
The flu and Covid are both caused by viral infections, but they come from different viruses. The flu is caused by influenza A, B, C, or D. COVID-19 is caused by a coronavirus known as SARS-CoV-2. This is different from other coronaviruses that cause seasonal colds.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Craig Sorkin, DNP, APN

Craig Sorkin, DNP, APN is a board certified Family Nurse Practitioner with over 15 years experience. He received his Undergraduate and Graduate degrees from William Paterson University and his doctoral degree from Drexel University. He has spent his career working in the Emergency Room and Primary Care. The last 6 years of his career have been dedicated to the field of digital medicine. He has created departments geared towards this specialized practice as well as written blogs and a book about the topic.