What Is Anthrax?

Medically Reviewed by Sabrina Felson, MD on September 14, 2023
5 min read

Anthrax is an infectious disease that’s caused by bacteria. It’s very rare in the United States, but it can be very serious.

It usually only affects farm animals like cows and sheep. But it’s possible to become infected if you’re in contact with infected animals or products that come from them. Anthrax has also been found in people who have injected heroin. Others at risk for anthrax include people who work with anthrax in a lab or those exposed to it because of bioterrorism.

Anthrax isn’t contagious, so you can’t spread it to other people.

You should see a doctor right away if you think you might have been exposed to it.

Anthrax is caused by a type of bacteria called Bacillus anthracis. Again, it’s rare in the United States, but it can live in the soil.

The bacteria make spores, which are a form of the bacteria that live in a protective shell. These spores can survive for a long time, even years, in soil. You can get anthrax if spores get into your body, break open and release the bacteria, which make toxins (poison) that harm you.

You could be exposed if you:

  • Breathe in the spores
  • Eat or drink something that’s tainted with the anthrax spores
  • Touch something that has the spores on it and they get into your body through cuts in your skin.
  • Inject tainted heroin (known as “injection anthrax,” it has happened only in northern Europe so far)

Most people who get anthrax work with infected animals, or with animal products like wool or hide.

If you get anthrax through a cut or sore on your skin, you might have:

  • A group of small, itchy blisters or a bump that looks like a bug bite
  • A sore on your skin that shows up after the blisters (usually painless and appearing on the face, neck, arms, or hands)
  • Swelling around the sore

If you eat or drink something that contains the spores, such as the undercooked meat of an infected animal, your symptoms could include:

  • Fever, chills
  • Swelling in your neck or glands and pain when you swallow
  • Nausea, loss of appetite, and vomiting, which may be bloody
  • Diarrhea that may be bloody
  • Headache
  • Stomachache
  • Redness in your eyes and face
  • Fainting
  • Pain and swelling in your abdomen

If you breathe in anthrax spores, this is the most dangerous situation. You could have:

If it worsens, you could also have other symptoms like shock or trouble breathing, or develop a condition called meningitis, which means there is inflammation in the membranes surrounding your brain and spinal cord. This can be life-threatening.

If you get anthrax by injecting illegal drugs like heroin, you might have:

  • A group of small blisters or bumps that may be itchy, or redness and swelling where you injected the drug
  • Fever and chills
  • A painless ulcer that replaces the bumps or blisters and has a black center
  • Pockets of pus around the injection site, either under the skin or in your muscle

If the disease gets worse, you could go into shock, develop meningitis, or your organs could stop working.

If your doctor thinks you have anthrax, you’ll get a test to check to see if you have anthrax antibodies or toxins in your blood. You might also get other tests, depending on the part of your body that’s affected.

If you have skin symptoms, your doctor may take a small sample of the affected skin to test in a lab. You might get an X-ray of your chest or CT scan if your doctor thinks you might have inhalation anthrax. And a stool test can look for signs of anthrax bacteria in order to diagnose gastrointestinal anthrax.

If you might have meningitis caused by anthrax, you may need to get a spinal tap, in which your doctor takes a bit of your spinal fluid to test.

If you think you’ve been exposed to anthrax, seek medical help right away -- even if you don’t notice symptoms, which may not show up right away.

You’ll get a blood test to check for antibodies to anthrax or toxin made by the anthrax bacteria in your blood. You may also have swabs of your skin or samples taken from your spinal fluid, stool, or mucus that you cough up.

Tell your doctor what happened. If they think you may have breathed in the spores that yield anthrax bacteria, you may get a chest X-ray or CT scan.

The treatment will depend on what happened and how you were exposed. You’ll get antibiotics, which you may get through an IV.

You may also need an antitoxin, which is a type of medicine that counters the poisons that anthrax bacteria make. Anthrax antitoxins include obiltoxaximab (Anthim) or  raxibacumab (ABthrax) to treat inhaled anthrax.

If your case is serious, you’ll get the treatment in a hospital.

There is an anthrax vaccine, but it’s only for people who are at risk because they might become exposed to anthrax. This group includes people who work in a lab with anthrax, some people who work with animals or animal products, and some members of the U.S. military.

The anthrax vaccine isn’t approved for use after exposure, but that might change in an emergency situation, such as if anthrax were used in terrorism. In that case, people who are exposed would need three shots of the vaccine over 4 weeks, and also take antibiotics for 60 days.