Anthrax: Symptoms, Causes, Treatment & Complete Guide

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026

Anthrax is a rare but serious illness caused by spores of the bacterium Bacillus anthracis [1]. It does not spread between people like a cold, and quick antibiotic treatment cures most infections — which makes acting fast after any suspected exposure the most important step.

Quick Answer

Anthrax is a rare but serious illness caused by the spore-forming bacterium Bacillus anthracis, usually caught through contact with sick animals, their meat or hides [1]. It does not spread from person to person like a cold. Quick antibiotic treatment cures most infections, so acting fast after suspected exposure is vital; inhaled anthrax is deadliest and can be fatal despite treatment [1].

What the research says

• Treatment sharply improves survival in systemic anthrax. A CDC-led systematic review of 764 adults and 167 children hospitalized with anthrax (1880–2018) found survival in patients with systemic symptoms rose from about 30% when untreated to about 70% with antimicrobials or antiserum/antitoxin; median incubation ranged from 1 day for injection anthrax to 7 days (IQR 4–9) for inhalation anthrax (Hendricks et al., Clinical Infectious Diseases, 2022) [3].

• Early treatment is what separates survivors from non-survivors in inhalation anthrax. In a review of 82 inhalational cases from 1900 to 2005, mortality was lower in the 2001 U.S. attack than in historical cases (45% vs. 92%), patients who reached the fulminant phase had a 97% mortality rate regardless of treatment, and starting antibiotics or antiserum in the early prodromal phase was linked to markedly better survival (Holty et al., Annals of Internal Medicine, 2006) [4].

• Combination antibiotics matter more than add-on antitoxin in the historical record. In a review of 605 hospitalized patients, monotherapy was sufficient for localized cutaneous anthrax, inhalation anthrax without meningitis fared better with at least two antimicrobials, and adding antitoxin/antiserum to antimicrobials did not improve survival; antibiotic prophylaxis after exposure reduced the risk of anthrax (Person et al., Clinical Infectious Diseases, 2022) [5].

Anthrax at a Glance

Aspect	Summary
Cause	Spores of Bacillus anthracis, a bacterium that lives in soil worldwide
Spore behavior	Can stay inactive in soil for years until they enter a host [1]
Spread between people	Does not spread person-to-person like a cold [1]
Four forms	Cutaneous (skin), gastrointestinal (food), inhalation (breathing), injection (drug injection)
Most common form	Cutaneous — enters through a cut or sore; mildest; rarely fatal with treatment [1]
Deadliest form	Inhalation — breathing in spores; often fatal even with treatment [1]
Symptom timing	Usually within 7 days of contact; sometimes weeks [1]
Standard treatment	Antibiotics, started as soon as possible; antitoxins for severe cases
Prevention after exposure	60 days of antibiotics + three-dose vaccine series, sometimes monoclonal antibodies [1]

What Is Anthrax?

Anthrax is a rare but serious illness caused by a spore-forming bacterium called Bacillus anthracis. Once spores enter the body, they form poisons that can destroy tissues. Anthrax mainly affects farm animals and wild game, and people can get infected through contact with sick animals [1].

Anthrax does not spread from person to person like a cold does. But anthrax spores can enter the body through a cut or scrape on the skin. Rarely, anthrax can be spread from someone who has an anthrax skin sore. Eating meat that has the germs or breathing in the spores also can cause anthrax [1].

Symptoms depend on how you are infected, and can include skin sores, vomiting, and shock. The good news is that quick treatment with antibiotics can cure most anthrax infections [1]. The sobering news is that inhaled anthrax is harder to treat and can be fatal.

Anthrax is rare in the United States, but the illness remains a public-health concern because the germs have been used in terrorist attacks — bioterrorism — in the country. In 2001, twenty-two people got anthrax after contact with powdered spores sent through the mail; five of those infected died [1]. This remains one of the few known episodes in which people got anthrax from something other than infected animals.

What are the symptoms of each type of anthrax?

Anthrax symptoms depend on which of the four common types of infection a person has, with each type causing its own symptoms. Most often, symptoms start within seven days of contact with the bacteria — but sometimes symptoms of anthrax can take weeks to appear [1].

Cutaneous Anthrax (Through the Skin)

A skin-related infection, called cutaneous anthrax, enters the body through the skin, most often through a cut or other sore. It is the most common way to get the disease and also the mildest form. With treatment, cutaneous anthrax rarely is fatal [1].

The symptoms include a raised, itchy bump that looks like an insect bite; within a day or two, the bump becomes an open, most often painless sore with a black center [1]. Other symptoms can include fever, and swelling around the sore and nearby lymph nodes. If the sore is on the face, neck, or chest, that swelling might cause trouble with breathing, eating, or drinking [1].

Gastrointestinal Anthrax (Through Food)

A gastrointestinal infection results from eating meat from an infected animal that is not cooked well enough. It can affect the throat, esophagus, stomach, and intestines [1].

Symptom	Detail
Nausea	Early digestive upset
Vomiting	May be bloody
Belly pain	Abdominal pain
Headache	Systemic symptom
Loss of appetite	Systemic symptom
Fever	Systemic symptom
Sore throat, painful swallowing	Throat and esophagus involvement
Swollen neck	Visible neck swelling
Severe, bloody diarrhea	Appears in the later stages of the disease [1]

Inhalation Anthrax (Through Breathing)

Inhalation anthrax comes from breathing in anthrax spores. It is the deadliest form of the disease and is often fatal, even with treatment [1].

The illness typically begins with flu-like symptoms for a few hours or days — sore throat, fever, tiredness, and muscle aches. It then progresses to chest discomfort, shortness of breath, nausea, coughing up blood, and painful swallowing. In the later stages it can cause high fever, shock (the collapse of the circulatory system that carries oxygen to cells), and meningitis (inflammation of the tissues around the brain and spinal cord) [1].

Injection Anthrax (Through Drug Injection)

Injection anthrax so far has been reported only in Europe and comes from injecting illicit drugs [1]. Early symptoms include bumps that might itch at the area of injection, and swelling around the sore.

When should you see a doctor about anthrax?

Here is the honest framing: many common illnesses start with symptoms like those of the flu, and the chances that a sore throat and aching muscles are due to anthrax are very small.

But the rule is simple and urgent: if you think you may have been in contact with anthrax, seek medical care right away [1]. If you develop symptoms after being in contact with animals or animal products in parts of the world where anthrax is common, seek medical care as soon as possible. Early diagnosis and treatment are needed — antibiotics work best when started as soon as possible [1] [2].

What causes an anthrax infection?

Anthrax spores are formed by anthrax bacteria that live in soil in most parts of the world [1]. The spores can be inactive for years until they enter a host. Common hosts for anthrax include wild animals and farm animals such as sheep, cattle, horses, and goats [1].

Although rare in the United States, anthrax is still common in farmed areas in other countries where animals are not regularly vaccinated against it. These regions include Central and South America, sub-Saharan Africa, Central Asia, southwestern Asia, southern and Eastern Europe, and the Caribbean [1].

Most human cases of anthrax come from contact with infected animals or their meat or hides [1]. The 2001 bioterrorism attack — powdered spores mailed to addresses in the United States — is one of the few known times that people got anthrax from something other than infected animals. Other outbreaks not linked to infected animals have been tied to injecting illicit drugs [1].

What are the risk factors for anthrax?

Anthrax requires contact with anthrax spores, and certain activities and settings make that exposure more likely. That exposure becomes more likely if you:

Risk factor	Why
Serve in the military in a high-exposure area [1]	Elevated risk of spore exposure
Work with anthrax in a laboratory setting	Direct handling of spores
Handle animal skins, furs, or wool from high-anthrax areas	Spores can live in hides and fibers
Work in veterinary medicine with farm animals	Contact with potentially infected livestock
Handle or dress game animals	Contact with wild game
Inject drugs such as heroin [1]	Injection anthrax route (seen in Europe)

What complications can anthrax cause?

The most serious anthrax complications involve the body's systems failing under the toxins the bacteria release.

Complication	What happens
Sepsis	The body cannot fight the infection; a chain reaction begins that can lead to damage of more than one organ system
Meningitis	Inflammation of the membranes and fluid covering the brain and spinal cord; can lead to hemorrhagic meningitis (bleeding) and death [1]
Shock	Collapse of the circulatory system that carries oxygen to cells

How can anthrax be prevented?

After exposure to anthrax spores, prevention involves 60 days of antibiotics, a three-dose anthrax vaccine series and sometimes monoclonal antibody treatment.

1. A 60-day treatment with antibiotics.

2. A three-dose series of anthrax vaccine.

3. Sometimes, monoclonal antibody treatment with raxibacumab and obiltoxaximab [1].

The Anthrax Vaccine

An anthrax vaccine exists for certain groups of people. Importantly, the vaccine does not contain live bacteria and cannot lead to infection, but it can cause side effects such as soreness at the injection site and allergic reactions [1].

The vaccine is not meant for everyone. It is for people in the military, scientists working with anthrax, and people in other high-risk jobs who handle animals or animal products. Protection involves five shots over 18 months plus yearly boosters [1]. The vaccine is also approved for people ages 18 through 65 who have been in contact with anthrax [1] — for example, after a terrorist attack using anthrax spores.

Avoiding Infected Animals

If you live in or travel to a country where anthrax is common and herd animals are not vaccinated, avoid contact with livestock and animal skins as much as possible. Also, do not eat meat that has not been cooked all the way through [1].

How is anthrax diagnosed?

Diagnosing anthrax starts with a practical question: what kind of work do you do, and how likely is it that you have been exposed to anthrax? The first step is to rule out other, more-common conditions that can cause your symptoms, such as the flu and pneumonia [2]. You may have a rapid flu test; if other tests are negative, doctors may test for anthrax directly [2].

Test	What it looks for
Skin testing	A sample of fluid from a skin sore, or a small tissue biopsy, tested in a lab for cutaneous anthrax [2]
Blood tests	Blood drawn and checked in a lab for anthrax bacteria [2]
Chest X-ray or CT scan	Helps diagnose inhalation anthrax [2]
Stool testing	Stool tested for anthrax bacteria to diagnose gastrointestinal anthrax [2]
Spinal tap (lumbar puncture)	A needle takes a small amount of spinal canal fluid to test for meningitis when anthrax is suspected to affect more than the skin [2]

How is anthrax treated?

The standard treatment for anthrax is antibiotics — and in some cases, antitoxin [2]. Which antibiotic or combination of antibiotics is used, and how long treatment lasts, depends on how you were infected, the strain of anthrax, your age, your overall health, and other concerns — including, in an outbreak, whether many people need treatment at once. Treatment works best when started as soon as possible [2].

Medicines

Since the 2001 attacks, researchers have developed antitoxin therapies — raxibacumab and obiltoxaximab — for inhalation anthrax. These medicines help get rid of the toxins the infection causes [2]. Anthrax immunoglobulin also may be used against the toxins. These medicines are given with antibiotics and can be obtained through the Centers for Disease Control and Prevention [2].

There is an important honesty point about the limits of treatment: some cases of anthrax respond to antibiotics, but advanced inhalation anthrax may not. By the later stages of the disease, the bacteria have often made more toxins than medicines can get rid of [2].

Therapies and Surgery

People with anthrax also may receive treatments to ease symptoms, including ventilators to help them breathe, and fluids and vasopressors (medicines that tighten blood vessels and raise blood pressure) [2].

Some cases of anthrax from injecting illicit drugs have been treated with surgical removal of infected tissue, and surgery may be needed for other types of anthrax as well. Other procedures may involve draining fluid that builds up in the lungs (pleural effusion) or in the belly (ascites) [2].

How should you prepare for an anthrax appointment?

Anthrax symptoms often come on suddenly and can be very serious. If you know you have been exposed to anthrax, or if you develop symptoms after a possible exposure, go to an emergency room right away [2].

If you have time before you go, make a list of:

• Your symptoms, including any that seem unrelated to anthrax.

• Key personal information, including recent travel to a part of the world where anthrax is common and whether you have been in contact with livestock, game animals, or animal skins.

• All medicines, vitamins, and supplements you take, including doses.

• Questions to ask your healthcare team — for instance, how you got infected, the treatment, and how you might respond to treatment.

Take a family member or friend with you, if possible, to help you remember the information you get.

Conclusion

• Rare but fast. Spores can lie dormant in soil for years and suddenly ignite an illness within seven days of contact.

• The route of infection determines both the symptoms and the outcome. The skin form is the most common and mildest; the inhaled form is the deadliest.

• Timing decides everything. Antibiotics cure most infections when started early, while advanced inhalation anthrax can outpace even the best medicines.

If you work with animals, animal products, or in a laboratory — or travel to regions where livestock are not vaccinated — knowing the warning signs and acting immediately on any suspected exposure is your best protection.

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Frequently Asked Questions

What is anthrax?

Anthrax is a rare but serious illness caused by a spore-forming bacterium called Bacillus anthracis. In the body, the spores form poisons that can destroy tissues. It mainly affects farm animals and wild game, and most human cases come from contact with infected animals, their meat, or their hides.

Can I catch anthrax from another person?

Anthrax does not spread from person to person like a cold. The rare exception is spread from someone who has an anthrax skin sore. Spores can enter through a cut or scrape on the skin, or through eating contaminated meat or breathing in spores.

What are the four types of anthrax?

Cutaneous (through the skin — most common and mildest), gastrointestinal (from undercooked meat), inhalation (breathing spores — the deadliest), and injection (from injecting illicit drugs — reported only in Europe so far).

What does cutaneous anthrax look like?

Cutaneous anthrax starts as a raised, itchy bump that looks like an insect bite, then within a day or two becomes an open, mostly painless sore with a black center, accompanied by fever and swelling around the sore and nearby lymph nodes.

When do symptoms appear?

Most often within seven days of contact with the bacteria, but sometimes symptoms can take weeks to appear. If you suspect exposure, seek medical care right away.

Is anthrax treatable?

Yes — quick treatment with antibiotics can cure most anthrax infections, and cutaneous anthrax rarely is fatal with treatment. Inhalation anthrax is harder to treat and can be fatal even with treatment, because by the later stages the bacteria have made more toxins than medicines can get rid of.

How is anthrax prevented after exposure?

The CDC recommends a 60-day course of antibiotics and a three-dose series of anthrax vaccine, sometimes combined with monoclonal antibody treatments (raxibacumab and obiltoxaximab). The vaccine is for military personnel, laboratory scientists, and other high-risk workers — five shots over 18 months plus yearly boosters — and is also approved for ages 18–65 after exposure.

References

1. Mayo Clinic Staff. Anthrax - Symptoms and causes. Mayo Clinic. Dec. 24, 2025. https://www.mayoclinic.org/diseases-conditions/anthrax/symptoms-causes/syc-20356203

2. Mayo Clinic Staff. Anthrax - Diagnosis and treatment. Mayo Clinic. Dec. 24, 2025. https://www.mayoclinic.org/diseases-conditions/anthrax/diagnosis-treatment/drc-20356209

3. Hendricks K, Person MK, Bradley JS, et al. Clinical features of patients hospitalized for all routes of anthrax, 1880-2018: a systematic review. Clin Infect Dis. 2022;75(Suppl 3):S341-S353. PMID: 36251560. https://doi.org/10.1093/cid/ciac534

4. Holty JEC, Bravata DM, Liu H, et al. Systematic review: a century of inhalational anthrax cases from 1900 to 2005. Ann Intern Med. 2006;144(4):270-280. PMID: 16490913. https://doi.org/10.7326/0003-4819-144-4-200602210-00009

5. Person MK, Cook R, Bradley JS, et al. Systematic review of hospital treatment outcomes for naturally acquired and bioterrorism-related anthrax, 1880-2018. Clin Infect Dis. 2022;75(Suppl 3):S392-S401. PMID: 36251553. https://doi.org/10.1093/cid/ciac536

Medical disclaimer

This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions about a medical condition.