Botulism is caused by the bacterium Clostridium botulinum, with a range of illnesses in humans and animals. Clostridium botulinum bacteria are found throughout the environment in soil, dust and some marine environments.

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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 3–30 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 or PlunketLine on 0800 933 922 or present to your local emergency department.

Botulism in older children and adults

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

In this age group, 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.

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.


Botulism can be treated and with appropriate care most people recover fully.

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 the anti-toxin called ‘Botulism Immune Globulin Intravenous’ (BIGIV), 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. Supplies of anti-toxin are available overseas if required.

Find out more from the Ministry

Food and Nutrition Guidelines for Healthy Infants and Toddlers (Aged 0–2) – the guidelines contain information on infant botulism and honey.

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