What Temperature Should Food Be Cooked To for Botulism Prevention?

Patient Presentation
The mother of an 11-month-old infant telephoned as she was cooking dinner and realized that she had put honey into the family’s stew. The food was being cooked in a home slow-cooker and would be cooked for several hours. She wanted to know if the infant could still eat the food since it would otherwise be appropriate for her. The nurse was not sure and asked the pediatrician who checked several reliable sources on the Internet. The pediatrician felt that although it was unlikely that a small amount of honey in the food would cause problems, the C. botulinum spores would not be killed at this temperature and advised not to feed the stew to the infant. He recommended other age-appropriate foods be offered instead.

Clostridium botulinum is a gram-positive, motile, anaerobic rod. C. botulinum produces spores which themselves produce a toxin that causes paralytic disease which may be fatal. About 145 cases per year are reported in the US.

  • Foodborne botulism is caused by eating food contaminated with the spores or toxin. 15% of US cases yearly.
  • Wound botulism is caused by a wound that is infected with the spores which produces toxin causing botulism. 20% of cases yearly.
  • Infantile botulism is considered separate from foodborne botulism and is caused by consuming the spores and the toxin is produced in the infant’s gut causing the disease. Adults can have the same problem but it is extremely rare. 65% of US cases yearly.
  • Iatrogenic – caused by an overdose of botulinum toxin.
  • Inhalation botulism is very rare.

Classic symptoms includes visual changes (e.g. blurred or double vision, ptosis), speech and swallowing difficulties, dry mouth and muscle weakness. Infants have a weak cry, poor tone and weakness, poor feeding and lethargy. If untreated symptoms can progress to paralysis of the extremities, trunk and respiratory muscles. With foodborne disease, symptoms can occur at 6 hours – 10 days after eating the contaminated food but generally within 18-26 hours.

The differential diagnosis for infantile botulism commonly includes meningitis/sepsis, electrolyte abnormalities, congenital myopathy and Werdnig-Hoffman disease.

Learning Point
There is no vaccine for C. botulinum, and anti-toxin is not useful for prevention. Heating to high temperatures will kill the spores. Temperature greater than boiling (212°F) is needed to kill spores so pressure cookers are recommended for home canning (reaching at least 250-250°F). The toxin is heat-labile though and can be destroyed at > 185°F after five minutes or longer, or at > 176°F for 10 minutes or longer. Boiling homecanned foods for 10 minutes or longer is recommended.

Home canned foods should follow strict hygienic practices to reduce contamination, especially low acidic foods such as asparagus, green beans, beets and corn. But any food has the potential to be contaminated. Boiling home-canned foods for 10 minutes is recommended to ensure safety.

Potatoes baked in aluminum foil do not kill spores and may actually help spores germinate and produce toxin if held at room temperature. Potatoes in foil must be kept hot before consumption or refrigerated. Oils that are infused with herbs or garlic should be refrigerated.

Honey can contain spores of C. botulinum and has been a source of infection for infants. Children less than 12 months old should not be fed honey. For persons older than 1 year it is safe.

All leftover food should be refrigerated within 2 hours after cooking and within 1 hour if the ambient temperature is > 90°F.

If ever in doubt about potential safety the food should not be consumed.

Questions for Further Discussion
1. What food sources are potentially contaminated with C. botulinum?
2. How is botulism treated?
3. What other cultural practices can put an infant at risk for C. botulinum?
4. Why is Botox® safe?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Botulism

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Schneider KR, Silverberg R, Chang A, Goodrich Schneider RM. Preventing Foodborne Illness: Clostridium botulinum. University of Florida IFAS Extension. Available from the Internet at http://edis.ifas.ufl.edu/fs104 (cited 2/17/15).

UCSB Science Line. What Kills Botulism?. University of California Santa Barbara. Available from the Internet at
(cited 2/17/15).

Centers for Disease Control. Botulism Facts for HealthCare Providers. Available from the Internet at http://emergency.cdc.gov/agent/botulism/hcpfacts.asp (rev. 4/19/2006, cited 2/17/15).

Centers for Disease Control. Botulism Overview for Clinicians: Prevention. Available from the Internet at http://emergency.cdc.gov/agent/Botulism/clinicians/prevention.asp (rev. 10/06/2006, cited 2/17/15).

World Health Organization. Botulism. Available from the Internet at http://www.who.int/mediacentre/factsheets/fs270/en/ (rev. 8/13, cited 2/17/15).

Centers for Disease Control. Botulism. Available from the Internet at http://www.cdc.gov/nczved/divisions/dfbmd/diseases/botulism/ (rev. 4/25/14, cited 2/17/15).


Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital