This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Clinical features

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Symptoms occur 18 to 36 hours after ingestion of the toxin.

Possible gastrointestinal symptoms include constipation - most frequent in infants (1) - and gastroenteritis - diarrhoea, cramps, vomiting. Fever is not associated with botulism.

Visual paralytic symptoms occur first - pupillary dilatation, blurred vision, diplopia, ptosis - and are followed by a general extreme fatiguability with severe weakness of the limbs and bulbar muscles. The voice changes.

On examination, tendon reflexes are usually preserved and usually there is no sensory disturbance or alteration of level of consciousness.

A milder condition occurs in infants and is associated with colonisation of the bowel by the organism.

Notes (1):

  • characteristic symmetric descending flaccid paralysis of motor and autonomic nerves: slurred speech, double vision, difficulty in swallowing, ptosis, respiratory muscle paralysis
    • in food botulism, diarrhoea and vomiting may precede neurological symptoms by a few hours
    • in infants, constipation is a frequent, often over-looked symptom


  • PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page

The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.


Copyright 2024 Oxbridge Solutions Limited, a subsidiary of OmniaMed Communications Limited. All rights reserved. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions receives funding from advertising but maintains editorial independence.