Last updated: May 15, 2023

Summarytoggle arrow icon

Botulism is a life-threatening condition of neuroparalysis that is caused by a potent neurotoxin produced by the spore-forming bacteria Clostridium botulinum. Botulinum toxin blocks the release of acetylcholine from presynaptic axon terminals into the synaptic cleft, irreversibly inhibiting neurotransmission. There are three main types of botulism: foodborne botulism, infant botulism, and wound botulism. Foodborne botulism results from the ingestion of a food product already contaminated with botulinum toxin (typically home-canned foods). Infant botulism represents the majority of cases and is caused by the ingestion of spores (commonly from honey or soil), which then germinate and produce neurotoxins within the intestinal tract. In wound botulism, which typically occurs in IV drug users, C. botulinum spores germinate in contaminated wounds. All three types present with neuroparalysis, while foodborne and infant botulism are sometimes also associated with gastrointestinal symptoms (e.g., discomfort, nausea, constipation). Clinical suspicion of botulism may be confirmed by quickly identifying the toxin in bodily fluids (e.g., serum, vomit, gastric acid, stool) and/or food. Foodborne botulism is best treated with an antitoxin and medically-induced bowel emptying. Treatment of infant botulism consists of the administration of botulism immune globulin. Wound botulism requires surgical debridement in addition to antitoxin administration.

Overviewtoggle arrow icon



  • Botulinum toxin: protease that cleaves SNARE proteins and prevents fusion of transmitter-containing vesicles with the presynaptic membrane → inhibition of acetylcholine release from the presynaptic axon terminals [1]

Clinical features

4 D's of botulism: Dysarthria, Diplopia, Dysphagia, and Dyspnea.


  • Rapidly identify botulinum toxin in samples from serum, vomit, gastric acid, stool, or suspicious foods.
  • Pathological EMG findings in affected muscles support the diagnosis. [2]


  • Secure airways.
  • See the corresponding sections for specific treatment measures.

Therapeutic/cosmetic botulinum toxin use


Foodborne botulismtoggle arrow icon

  • Etiology
    • Ingestion of preformed botulinum toxin via contaminated foods
      • The anaerobic spores survive in poorly pasteurized canned foods (e.g., vegetables with soil contact, meat, home-fermented tofu) [5]
      • Germination of the spores produces dangerous toxins (botulinum toxins = enterotoxins A-F) and gas → bulging cans
  • Incubation period: 12–36 hours
  • Specific treatment
    • Horse-derived heptavalent botulism antitoxin
    • Eradication of toxin through bowel emptying (induced by medication)
  • Prevention
    • Sterilize food through autoclaving.
    • Food should be boiled twice before being canned to kill spores that may have germinated after the first round of boiling.


Infant botulismtoggle arrow icon

  • Etiology: ingestion of spores
    • Spores may be present in honey, juice, and contaminated soil.
    • Germination of the spores in intestinal tract → synthesis of botulinum toxin
  • Incubation period: days to 4 weeks
  • Clinical features: Infants may present with infantile hypotonia
    • Ptosis
    • Floppy movements
    • General weakness
    • Poor feeding (weak sucking)
  • Differential diagnosis:
Differential diagnosis of infantile hypotonia [6]
Condition Etiology Clinical features Management
Infant botulism
  • Constipation (can be a presenting sign)
  • Descending palsy (usually starts with ptosis)
  • Hypotonia
  • Poor feeding, weak sucking
  • Respiratory compromise
Neonatal myasthenia gravis
Spinal muscular atrophy type 1
Myotonic dystrophy type 1
  • Supportive care
Trisomy 21
  • Supportive care
  • Management of gastrointestinal and cardiovascular anomalies
  • Specific treatment: IV human botulism immune globulin (BIG-IV)
  • Prevention: Avoid exposure of < 1-year-old infants to potentially contaminated material (e.g., raw honey, dust, soil).

A stool sample should be obtained for culture and toxin testing, because serum studies in infants often yield false negative results. [7]

Treatment should not be delayed if there is a high clinical suspicion of infant botulism. [8]


Wound botulismtoggle arrow icon

  • Etiology: germinating spores in contaminated wounds (most common among IV drug users)
  • Incubation period: 10 days (ranges from 4–14 days)
  • Specific treatment
  • Prevention
    • Government-sponsored sterile needle and syringe programs
    • Avoidance of IV drug use
    • Seek medical attention for infected wounds.

Differential diagnosestoggle arrow icon


The differential diagnoses listed here are not exhaustive.

Referencestoggle arrow icon

  1. Botulism Associated with Home-Fermented Tofu in Two Chinese Immigrants — New York City, March–April 2012. Updated: July 13, 2013. Accessed: October 21, 2020.
  2. Botulism. Updated: January 1, 2018. Accessed: March 31, 2018.
  3. Dhaked RK, Singh MK, Singh P, Gupta P. Botulinum toxin: bioweapon & magic drug.. Indian J Med Res. 2010; 132: p.489-503.
  4. Sobel J. Botulism. Clinical Infectious Diseases. 2005; 41 (8): p.1167-1173.doi: 10.1086/444507 . | Open in Read by QxMD
  5. Nigam P, Nigam A. Botulinum toxin. Indian J Dermatol. 2010; 55 (1): p.8-14.doi: 10.4103/0019-5154.60343 . | Open in Read by QxMD
  6. Peredo DE, Hannibal MC. The Floppy Infant: Evaluation of Hypotonia. Pediatrics in Review. 2009; 30 (9): p.e66-e76.doi: 10.1542/pir.30-9-e66 . | Open in Read by QxMD
  7. Cox N, Hinkle R. Infant botulism. Am Fam Physician. 2002; 65 (7): p.1388-1392.
  8. Infant Botulism: Information for Clinicians. Updated: October 13, 2020. Accessed: November 16, 2020.
  9. Botulism. Updated: February 18, 2016. Accessed: March 27, 2017.

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