SynopsisCodesLook ForDiagnostic PearlsDifferential Diagnosis & PitfallsBest TestsManagement PearlsTherapyDrug Reaction DataReferences

Information for Patients

View all Images (8)

Potentially life-threatening emergency
Other Resources UpToDate PubMed
Potentially life-threatening emergency


Contributors: Lewis Rubinson MD, PhD, David R. Lane MD
Other Resources UpToDate PubMed


This summary discusses adults and children. Botulism in infants is addressed separately.

Botulism is caused by a group of paralytic neurotoxins produced by the spore-forming anaerobic gram-positive bacillus Clostridium botulinum. Botulinum toxin irreversibly binds to the pre-synaptic cholinergic neuromuscular junction, blocking acetylcholine release and manifesting as a symmetric progressive descending flaccid paralysis with bulbar palsies after an 18- to 72-hour incubation period. Multiple cranial nerve palsies are evident early in the course of the disease. Symptom severity ranges from mild to frank paralysis. Botulism has a mortality rate of 5%-10% (up to 30% in victims over 60 years of age).

Intoxication can occur naturally from contaminated foods or rarely as a result of wound or intestinal colonization in humans. There are 7 types of botulinum toxins, A through G, although only A, B, E, and F have been implicated in the poisoning of humans. Botulinum toxins are odorless and colorless in solution. Botulism is not spread person to person.

People at higher risk for contracting food-borne botulism are nursing home residents, dormitory residents, wedding guests, and large event attendees. Intestinal botulism occurs in infants, and wound botulism must be suspected in IV drug users, particularly black tar heroin users, who present with weakness (in addition to cerebral infection or epidural abscess).

In food-acquired cases, nausea, vomiting, and diarrhea may precede the paralysis, and cases will cluster around consumption of the contaminated food at a restaurant or from improper home canning.

Patients are afebrile with initial complaints of blurred vision, diplopia, and mydriasis with photophobia, ptosis, ophthalmoplegia, hoarseness, dysarthric speech, and dysphagia. Constipation, dry mouth, and urinary retention may also occur. Patients remain awake, alert, and oriented throughout the entire illness. Symptoms progress in a descending pattern to produce a skeletal muscle paralysis that may cause sudden respiratory arrest and death if untreated. Severe poisonings may require months of ventilatory support.

If you have high suspicion for botulism, it is imperative to notify public health officials immediately. They will assist with gauging the likelihood of disease and are the only group who can release the antidote (an antitoxin). Best available data suggests that antitoxin, when administered early, is associated with better clinical outcomes. Antitoxin is available from the US Centers for Disease Control and Prevention (CDC).

Botulinum Toxin and Bioterrorism
Botulism is classified as a Category A bioterrorism agent because of its ease of dissemination and high mortality rate. When used as a biological weapon, botulinum toxin is most likely to be dispersed as an aerosol for inhalation, although it could be added to the food or water supply. Following an aerosol release, the toxin may be swallowed as well as inhaled.


A05.1 – Botulism food poisoning

398565003 – Botulism

Look For

Subscription Required

Diagnostic Pearls

Subscription Required

Differential Diagnosis & Pitfalls

Multiple / many patients with weakness:

Best Tests

Subscription Required

Management Pearls

Subscription Required


Subscription Required

Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

Subscription Required


Subscription Required

Last Updated:01/09/2019
Copyright © 2023 VisualDx®. All rights reserved.
Potentially life-threatening emergency
Patient Information for Botulism
Print E-Mail Images (8)
Contributors: Medical staff writer


Botulism is caused by the bacterium Clostridium botulinum, which occurs naturally in soil. There are three common types of botulism that affect humans: foodborne botulism (food poisoning), wound botulism (the bacteria invade an open wound), and infant botulism. Botulism is a serious condition and is considered a medical emergency.

Foodborne botulism – Occurs from eating contaminated food and causes vomiting and diarrhea. It can also affect the nervous system, causing muscle paralysis. If left untreated, the muscle paralysis can interfere with your ability to breathe.

Wound botulism – Occurs when bacteria infest an open wound. This can be spread by injection drug use.

Infant botulism – Can occur when infants eat foods such as raw honey, but infants can also pick up botulism from infected dirt or dust.

Who’s At Risk

Most cases of foodborne botulism are caused by eating improperly canned foods.

Intravenous drug users are at a higher risk of contracting wound botulism.

Signs & Symptoms

Foodborne botulism symptoms typically begin 18-36 hours after eating contaminated food. The symptoms include:
  • Dry mouth
  • Difficulty swallowing or speaking
  • Drooping eyelids
  • Trouble breathing
  • Blurred vision
  • Nausea
  • Vomiting
  • Abdominal cramps
Wound botulism symptoms include:
  • Difficulty swallowing and speaking
  • Drooping eyelids
  • Trouble breathing
  • Blurred vision
Infant botulism symptoms include:
  • Constipation
  • Weak cry
  • Drooling
  • Drooping eyelids
  • Difficulty sucking or feeding

Self-Care Guidelines

If botulism is suspected, seek medical care immediately.

To prevent infant botulism, avoid giving honey to babies younger than 1 year. To prevent food botulism, learn and follow proper home canning techniques.

When to Seek Medical Care

Seek medical care immediately if you suspect you have botulism or if you have a wound that has become infected.


Your doctor will monitor your heart rate and breathing. If your botulism is very severe, you may have trouble breathing and need to be put on a ventilator. Antitoxins can shorten your recovery time.

Foodborne botulism – Your doctor may induce vomiting to remove contaminated food in your gut.

Wound botulism – A doctor may surgically remove the infected source. Antibiotics are also given.

Infant botulism - Antitoxin is given to infants. Most infants will need a hospital stay, and the staff will monitor breathing and food intake.
Copyright © 2023 VisualDx®. All rights reserved.
Potentially life-threatening emergency
A medical illustration showing key findings of Botulism : Diplopia, Dysarthria, Eyelid ptosis, Flaccid paralysis, Dysphagia, Dysphonia
Illustration image of Botulism - imageId=1314097. Click to open in gallery.
Copyright © 2023 VisualDx®. All rights reserved.