What is botulism?

Botulism is a serious illness that affects the nervous system. It occurs when poisonous substances called botulinum toxins produce skeletal muscle paralysis. This paralysis can affect the muscles that help you move and breathe.

Botulism is rare. But because it can cause death, it is important for people with symptoms of botulism to see a doctor right away.

What are the types of botulism?

There are several different kinds of botulism. Three kinds of botulism are the most common:

Foodborne botulism

Foodborne botulism happens when people eat contaminated foods that already contain the toxin.

Incorrectly processed food may allow the bacteria to grow which then releases the toxin into the food. Home-canned or improperly canned store-bought foods are common sources of foodborne botulism. Other food sources associated with this illness include:

  • Oils infused with herbs
  • Potatoes baked in aluminum foil
  • Cheese sauces
  • Bottled garlic
  • Foods kept warm or left unrefrigerated for too long

Infant botulism

Infant botulism typically occurs when babies ingest bacterial spores which are commonly found in soil or are fed foods which contain the spores, the most common being honey. The spores then become bacteria, which grow inside the baby’s intestines and release toxin.

Older children and adults have natural defenses against colonization, but infants younger than 12 months old don’t have those defenses. For this reason, experts advise that babies shouldn’t eat honey until they are at least 1 year old.

Wound botulism

Wound botulism develops when clostridium bacteria gets into a wound and grows. This type of botulism most often occurs in people who use a needle to inject drugs into their veins. In rare cases, it can also develop after surgery or a serious injury.

How common is botulism?

Few cases of botulism are reported in the United States each year. In 2016, 205 confirmed botulism cases were reported to the Centers for Disease Control.

What causes botulism?

Certain bacteria, including clostridium botulinum and clostridium butyricum, produce botulinum toxins. The spores of these bacteria are commonly found in soil but only rarely make people sick.

Specific conditions can cause bacterial spores to germinate and grow. These mature bacteria then secrete the toxin. When the toxin is released, it quickly spreads into the bloodstream and attaches to nerves. Botulism develops when those nerves no longer work. Conditions that allow spores to germinate include:

  • Lack of oxygen
  • Low acidity, sugar or salt
  • Cooking temperatures that are too low (even boiling may not destroy the spores)
  • Storage temperatures that are too warm

What are the symptoms of botulism?

Symptoms of botulism usually begin in the muscles of the face, eyes and throat. Without treatment, symptoms can spread to other parts of the body. Signs can appear from a few hours to several days after ingesting botulism spores. Symptoms include:

  • Drooping eyelids
  • Double or blurred vision
  • Slurred speech
  • Dry mouth
  • Trouble swallowing
  • Difficulty breathing
  • Weakness of paralysis of arms or legs

Last reviewed by a Cleveland Clinic medical professional on 05/14/2018.


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