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- National Center for Biotechnology Information - Botulism (Oct. 17, 2026)
botulism
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What is botulism?
Botulism is a paralytic syndrome caused by botulinum toxin, a poisonous protein produced by Clostridium botulinum bacteria that induces neurotoxicity and muscle paralysis. Botulism occurs most frequently from eating improperly sterilized home-canned foods that contain the toxin, but can also result from wound infection.
Once ingested, the toxin is absorbed rapidly and carried in the blood to nerve endings in muscles, where it exerts its effects. It specifically attacks the autonomic nervous system by blocking the release of acetylcholine, a neurotransmitter involved in muscle contraction. In the absence of acetylcholine release from neurons, muscles can no longer contract, resulting in flaccid paralysis, wherein affected muscles become weak and limp.
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What causes botulism?
Botulism is a paralytic syndrome caused by botulinum toxin, a poisonous protein produced mainly by Clostridium botulinum bacteria. Botulism is frequently caused by eating improperly sterilized home-canned foods that contain the toxin. It can also result from wound infection.
C. botulinum bacteria produce heat-resistant spores that may contaminate fresh food to be canned. Inside a sealed can, the spores germinate, releasing bacteria. As the bacteria multiply, they secrete botulinum toxin, which damages the autonomic nervous system by blocking the release of acetylcholine, a neurotransmitter that allows muscle contraction.
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How does the toxin produced in botulism affect the body?
Botulinum toxin, produced by Clostridium botulinum bacteria, causes botulism, a paralytic illness. The toxin is absorbed into the bloodstream and attacks the autonomic nervous system by preventing the release of acetylcholine, a neurotransmitter that enables muscle contraction. This leads to flaccid paralysis, where muscles weaken and become limp.
Initial symptoms include nausea, vomiting, headache, fatigue, and dizziness. As muscle paralysis progresses, it can cause blurred vision, slurred speech, dry mouth, difficulty swallowing, and generalized muscle weakness. Paralysis of respiratory muscles can cause breathing difficulties and may result in death.
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What are common symptoms of botulism?
Botulism, a paralytic syndrome, arises from botulinum toxin, produced by Clostridium botulinum bacteria, often from improperly sterilized home-canned foods. Once ingested, the toxin swiftly absorbs, traveling via blood to nerve endings in muscles, disrupting the autonomic nervous system by hindering acetylcholine release, crucial for muscle contraction, leading to flaccid paralysis.
Initial symptoms of foodborne botulism include nausea and vomiting, typically within six hours of consuming contaminated food, followed by headache, fatigue, and dizziness. Paralysis can affect eyelid muscles, causing blurred or double vision. As paralysis progresses, slurred speech, dry mouth, difficulty swallowing, and general muscle weakness emerge. Respiratory muscle involvement can cause breathing difficulties and may result in death.
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How is botulism diagnosed by doctors?
Diagnosis of botulism is greatly enhanced by early detection and prompt administration of botulism antitoxins. Electromyography (EMG), the study of the electrical characteristics of muscles, may provide useful data for diagnosis. During muscular contraction, electrical activity increases; waveforms recorded with primary muscle disease differ from those occurring when muscles are deprived of motor innervation. With nerve conduction studies (NCS), the speed of conduction of impulses along sensory and motor fibers can be measured, potentially indicating the nature and sites of peripheral nerve disorders.
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What treatments are available for someone with botulism?
Early diagnosis and prompt administration of botulism antitoxin, containing animal-derived antibodies that neutralize the toxin, greatly enhance survival from botulinum toxin poisoning. The antitoxin is administered intravenously in large doses, but its ability to dislodge the toxin from nerve fibrils within muscles is doubtful.
Additional treatments include guanidine hydrochloride, which counteracts the toxin's action on nerve endings, but it should be administered carefully due to its toxicity. If the patient can be kept alive, paralyzed muscles can recover. The best hope of survival may include tube feeding, a tracheotomy, and the use of an artificial respirator.
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botulism, paralytic syndrome caused by poisoning by botulinum toxin, a substance produced by Clostridium botulinum bacteria. Botulism results most frequently from the eating of improperly sterilized home-canned foods containing the toxin. Poisoning also may result from wound infection.
C. botulinum bacteria—which cannot survive in the presence of oxygen—normally live in the soil, where they form heat-resistant spores that may contaminate fresh food to be canned. The spores survive if the food is not cooked at 120 °C (248 °F) for a sufficient length of time; this temperature can be achieved with certainty only in commercial canning plants or in a pressure cooker; an exception is acidic foods with a pH below 4.6, such as tomatoes, which can be processed by boiling. Then, inside the sealed can, the spores germinate and release the bacteria, and, as the bacteria multiply, they secrete botulinum toxin, a protein that is one of the most potent poisons known. Unlike the clostridial spores, the toxin is readily destroyed by heat; it remains potent only if the contaminated food is not heated to at least 70 °C (158 °F) for two minutes before it is eaten.
Once ingested and absorbed, C. botulinum toxin damages the autonomic nervous system by blocking the release of acetylcholine, a neurotransmitter that allows muscle contraction. When the toxin is swallowed in food, it is absorbed rapidly and carried in the bloodstream to nerve endings in muscles. The toxin attacks the fine nerve fibrils and stops the impulse from passing along these fibres. No acetylcholine is released and the muscle cannot contract; it is paralyzed.
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The first symptoms of botulism, nausea and vomiting, usually appear six hours or less after the contaminated food is eaten, depending upon the amount of toxin ingested. The poisoned person becomes tired and may complain of headache and dizziness. The muscles of the eyelid may be paralyzed, a sign that may appear within hours of eating the food. The vision is often blurred, and the affected person may see double. Next, the paralysis affects the muscles used for speech. The mucous membranes of the throat may become dry; the affected person may feel a constriction in the throat, soon associated with difficulty in swallowing and speaking; and a general muscle weakness soon occurs.
The respiratory muscles become involved; about half the deaths from botulism result from paralysis of the respiratory muscles. The person remains conscious through most of the illness, until suffocation occurs. Death may come within a day, although people less severely poisoned may live for a week. Few who reach the stage of severe paralysis survive, although a person who survives the paralysis will recover completely. Infant botulism, which may result from feeding infants honey contaminated with the clostridial spores, exhibits symptoms such as constipation, poor feeding, and a weak cry; children under the age of one year should not be given honey because of this risk.
With early diagnosis, the chance of a person’s surviving is greatly enhanced by the prompt administration of botulism antitoxins, which contain equine antibodies that neutralize the toxin in the body. C. botulinum antitoxin is given in large doses intravenously, but it is doubtful that antitoxin can do anything to dislodge the toxin once it has reached the nerve fibrils. A chemical, guanidine hydrochloride, counteracts the action of C. botulinum toxin on nerve endings and has been used successfully in treatment, but it is itself a toxic substance that should be given only with great care. Paralyzed muscle can recover if the patient can be kept alive, and perhaps the best hope of survival in otherwise desperate cases lies in tube feeding, a tracheotomy (making an opening in the trachea, or windpipe), and use of an artificial respirator.