What Is Valley Fever?

Medically Reviewed by Carol DerSarkissian, MD on May 10, 2021

Many of us are more familiar with the fever, chills, and other signs of the flu than we’d like to be. If you live in the southwestern United States or certain other areas, there’s a small chance that these symptoms could signal something else: valley fever.

Valley fever isn’t contagious, so you can’t catch it from someone else. Fungus that grows in the ground causes it. When something stirs up the soil, spores from the fungus fly into the air, where people breathe them in.

Most people don’t get sick. And when valley fever symptoms do appear, they usually go away on their own. If not, there are medicines that can typically clear them up. But in rare cases, the fungus spreads to other parts of the body. That’s much more serious, so it’s important to know what’s happening.

Another reason to keep a lookout: Pets can come down with valley fever, too.

You might hear your doctor use the medical name for valley fever: coccidioidomycosis. It is also known as San Joaquin Valley fever or desert rheumatism.

Where It Happens

The types of fungus that cause valley fever thrive in dry, desert soil. When the wind picks up their spores, it can blow them for hundreds of miles. They exist in these areas of the U.S.:

  • Arizona
  • Southwestern New Mexico
  • Areas around El Paso, Texas
  • Central and Southern California, especially the San Joaquin Valley
  • Eastern Washington state

The fungus’ area also reaches down into Mexico. And it has turned up in Central and South American countries, including Argentina, Brazil, Colombia, Guatemala, Honduras, Paraguay, and Venezuela.

Who’s At Risk

If you go to the affected regions, you could be exposed. Someone who is age 60 or older is more likely to get it. The risk is also greater for:

  • People with weakened immune systems
  • Pregnant women
  • People with diabetes
  • African-Americans, Hispanics, Native Americans, and Filipinos, likely due to genetic reasons

Signs of valley fever usually show up 2 to 3 weeks after the fungus gets into your lungs. You might have:

If symptoms do appear, recovering from them may take months. The time depends on your general health and how many of the fungus spores have gotten into your lungs.

If symptoms don’t improve on their own or you don’t get treatment, valley fever may eventually develop into a long-term type of pneumonia. This mainly happens in people whose immune systems are weak. The symptoms include milk fever, unexplained weight loss, chest pains, and coughing up mucus with blood in it.


In the most serious cases, the infection moves beyond the lungs into other parts of the body.

The possible effects include skin sores that are worse than the rash mentioned above, painful, swollen joints, and meningitis, which is an infection around the brain and spinal cord.

When to Call the Doctor

Make the call if you have symptoms of valley fever and they last more than a week. Checking with a professional is especially important if you’re in a high-risk group.


The main test for valley fever is for your doctor to take a sample of your blood. The results should come back in a few days.

You may also be asked to cough up a mucus sample so it can be tested.

Your doctor might take an X-ray.

They might also take a sample of tissue from your body. If the tissue or blood needs to go to a lab for more tests, the results might need a few weeks to get back to your doctor.


Valley fever usually doesn’t need medical treatment. For people who are otherwise healthy, bed rest and drinking plenty of fluids are enough. Your doctor will keep a close watch on how you’re doing.

If the symptoms hang on or get worse, your doctor might prescribe a drug that attacks illnesses caused by fungus. There are several options, depending on how severe the symptoms are. In the most extreme cases, such as people who develop meningitis, lifelong medication may be necessary.

One bit of good news: In many cases, people who have valley fever become immune for the rest of their lives.

Since you can’t spread it to other people, you don’t have to stay home for that reason. But it’s important to get as much rest as possible until your symptoms are gone.

Can You Prevent It?

There’s no vaccine. But if you live in or visit a region where valley fever is a possibility, it helps to take common-sense precautions, such as:

  • Avoid dusty areas, such as construction sites
  • Stay indoors during dust storms, and keep the windows shut
  • Avoid activities that put you in contact with dust and soil, such as yard work and gardening
  • Filter the air inside your home

These steps are particularly important for people who are at high risk.

Animals Can Get It, Too

You can’t spread valley fever to, or get it from, your pet. But animals can get it on their own.

Dogs are most vulnerable. Just like with people, many of the animals that inhale the fungus don’t get sick. When they do, they may cough, lack energy, or lose weight. If you think your pet may have valley fever, check with your vet.

Show Sources


Center for Food Security & Public Health, Iowa State University: “Coccidioidomycosis.”

CDC: “Valley Fever (Coccidioidomycosis).”

Mayo Clinic: “Valley fever.”

Merck Manual: “Coccidioidomycosis.”

© 2021 WebMD, LLC. All rights reserved. View privacy policy and trust info