Botulism is a very rare but life-threatening condition that causes paralysis (muscle weakness).


Botulism is caused by toxins produced by Clostridium botulinum bacteria. Clostridium botulinum bacteria are found throughout the environment in soil, dust, honey and some marine environments.

There are three types of botulism:

  • intestinal botulism
  • food-borne botulism
  • wound botulism.

Intestinal botulism is the most common form of botulism. Young children are most susceptible. Intestinal botulism is caused by spores being swallowed by eating food, particularly honey, or dust or soil that contains Clostridium botulinum spores, which grow inside the intestines and produce toxins. Intestinal botulism affecting children under 12 months of age is known as infant botulism

While intestinal botulism involves consuming the botulism bacteria, food borne botulism involves eating toxins formed by bacteria in food.

Botulism can also develop when a wound is infected with the bacteria. The bacteria in the wound produce the toxin, which is absorbed from the wound site. Wound botulism is rare.


Intestinal botulism (infant botulism)

Infant botulism is caused by spores being swallowed and growing in the intestines. The bacteria that have grown then produce a neurotoxin which is absorbed into the bloodstream and affects muscle strength. Babies up to 6 months old are more likely to get infant botulism but it can occur up to 1 year old.

Symptoms can begin 3 to 30 days after the spores are swallowed.

  • The first symptom is constipation lasting 3 days or more.
  • This can be followed by:
    • reduced facial expressions
    • poor feeding (weak suck)
    • weak cry
    • lethargy
    • floppiness.
  • Later symptoms include:
    • trouble swallowing saliva, which causes excessive drooling
    • generalised muscle weakness
    • breathing difficulties.

These symptoms can develop over about a week.

Infant botulism is a very rare condition. Constipation and poor feeding in babies will almost certainly have another cause, but medical advice should always be sought for these symptoms.

If you are concerned that your child might have infant botulism please:

  • see your GP urgently,
  • call Healthline on 0800 611 116,
  • call PlunketLine on 0800 933 922 or
  • present to your local emergency department.

Food-borne botulism

Over the age of 1 year the intestines are usually mature enough to prevent spores growing and intestinal botulism is rare.

In older children and adults, botulism occurs when people eat food that has been kept in an environment where the bacteria can grow and produce the neurotoxin. This most commonly occurs with preserved vegetables, meat and fish.

Symptoms usually develop 12–36 hours after eating the contaminated food.

  • The first symptoms are nausea, vomiting and diarrhoea.
  • Later symptoms are paralysis of the eyes, mouth, and throat, and then progressively other muscles.

Wound botulism

Wound botulism causes similar symptoms to foodborne botulism but may take up to 2 weeks to occur.


Botulism is a very serious condition that requires immediate medical attention.

Botulism can be treated and with appropriate care most people recover fully. Treatment is more effective the earlier it's started.

If your doctor suspects that someone has botulism, they will be referred to hospital where they can be tested for bacteria and toxins.

The affected person will be monitored and if necessary given an anti-toxin, which if given early in the course of the illness significantly reduces the time of intensive care required. The neurotoxin effects wear off over time but the affected person may require intensive care and ventilation during this process if the breathing muscles have been affected.


Avoid giving honey to babies under 12 months.

People who preserve their own fruit, vegetables or meats should take special care with cooking temperatures, container sterilisation and salt and acidity levels to make sure the process does not encourage bacteria to grow. Throw away all canned foods that show any signs of being spoiled or are out of date.

Wash any wound thoroughly with antibacterial soap and keep clean.

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