Viral Infections

What Is a Viral Infection?

A viral infection happens when a virus gets into your body and starts multiplying. Viruses are very small germs that invade your body’s cells and use them to make more viruses. Some viral infections are mild, like the common cold, while others can be more serious, like the flu or COVID-19.

There are many different types of viruses, and each one can affect the body in different ways. Virus infections can affect the nose, throat, lungs, stomach, skin or other organs.

What Causes Viral Infections?

Viruses spread in several ways, depending on the type. Common ways you can catch a virus include:

• Breathing in droplets from a cough or sneeze
• Touching a surface with the virus and then touching your mouth, nose or eyes
• Eating or drinking contaminated food or water
• Close contact with an infected person
• Being bitten by an insect that carries a virus (like a mosquito or tick)
  
  

Once inside your body, the virus uses your own cells to make copies of itself. This process can trigger your immune system, causing the symptoms of an infection.

Common Viral Infection Symptoms

Because there are so many viruses, symptoms can vary. Common signs include:

• Fever or chills
• Cough, sore throat or runny nose
• Headache or body aches
• Fatigue or weakness
• Nausea, vomiting or diarrhea (in stomach viruses)
• Skin rashes (in viruses like chickenpox or measles)
  
  

Some symptoms may start mildly and worsen over time, while others go away within a few days.

How Are Viral Infections Diagnosed?

To diagnose a viral infection, your health care provider may:

• Ask about your symptoms and recent exposure to illness
• Do a physical exam
• Take a sample of blood, mucus, saliva, or stool
• Use rapid tests, especially for viruses like COVID-19, flu, or RSV
• Order blood tests or imaging if symptoms are severe or unusual
  
  

In many cases, the doctor can diagnose a viral infection based on symptoms and time of year (such as flu season).

Unlike bacterial infections, antibiotics do not work on viruses. Most viral infections get better with rest and supportive care. Here’s how they’re usually treated:

Home Treatments

• Rest and get enough sleep
• Drink plenty of fluids to avoid dehydration
• Use over-the-counter medicine (like acetaminophen or ibuprofen) to reduce fever or pain
• Eat healthy foods and avoid stress on your body
  
  

Prescription Antivirals
Some serious viral infections may be treated with antiviral medications, such as:

• Oseltamivir (Tamiflu) for flu
• Antiviral drugs for COVID-19, herpes, hepatitis, or HIV
  
  

These medicines can help shorten the illness or prevent complications, but they must be taken early in the infection.

How to Prevent Viral Infections

Preventing viruses is often easier than treating them. You can lower your risk of getting sick by:

• Washing your hands often with soap and water
• Avoiding close contact with sick people
• Covering coughs and sneezes with your elbow
• Cleaning surfaces like doorknobs and phones
• Getting recommended vaccines (flu, COVID-19, measles, etc.)
• Wearing a mask in crowded or high-risk areas, especially during outbreaks
• Staying home when you’re sick to avoid spreading germs
  
  

Good hygiene, a strong immune system, and staying up to date on vaccinations can help protect you and others.

Next Steps
If you have symptoms of a viral infection that don’t go away after a few days — or if you’re at high risk of complications — see your health care provider. While most viral illnesses are mild, early care can prevent serious problems.