Although rare, botulism is a serious illness caused by toxins that affect the nerves, leading to breathing difficulties, muscle paralysis and even death. The scentless, tasteless and invisible toxins are primarily produced by Clostridium botulinum bacteria and sometimes by Clostridium butyricum and Clostridium baratii. The bacteria require an anaerobic environment (without oxygen) which is low in acids, sugars and salt and within a certain temperature range with adequate amount of water to satisfy the conditions required by the bacteria in order to multiply and produce the toxin releasing spores. Examples of food-borne botulism include improperly home-canned, preserved or fermented foods which have provided satisfactory conditions for bacterial development, multiplication and production of botulinum toxins. People can become severely ill or even die if they consume contaminated foods.
(CDC, 2026)
Home canning safety
For a complete guide to home canning, head over to the National Center for Home Food Preservation website where you can find the online version of the USDA (United States Department of Agriculture) 2015 Complete Guide to Home Canning which not only includes guides on home preservation of your produce but also comes with directions and recipes for fruit, tomato and vegetable canning allowing you to make use of your harvest further into the year, promoting sustainability and self-sufficiency. Your own vegetables on Christmas Day as you sit around the table showcasing your hard work this year. Pasta night with the kids on a cold winter night. Hoping that tomatoes will yield well, why not can tomatoes or make your own passata, chopped tomatoes, tomato puree… The linked guide will help you achieve your goals safely, reducing the risk of poisoning.
(National Center for Home Food Preservation, n.d.)
Other types of Botulism
Other types of botulism include wound botulism, caused by bacteria infecting a wound (most commonly by intramuscular use of illicit substances contaminated with the bacteria) and infant botulism, which can occur if the bacterial spores get into an infants intestines where they produce toxins and cause illness (the reason it is not advised to introduce honey to infants <12 months of age).
Seeking medical assistance and treatment
Onset of symptoms can vary from a few hours to several days following exposure to the C. botulinum bacteria or their toxins. Initial symptoms normally include nausea, vomiting, abdominal cramps, diarrhea or constipation.
Without seeking medical assistance, botulism eventually leads to a descending symmetric paralysis which spreads down the body from head and progressing down with symptoms including drooping eyelids, blurred or double vision, facial muscle weakness, dysphagia (difficulties swallowing), slurred speech and breathing difficulties. A medical emergency similar to a stroke which unlike botulism, usually causes a sudden maximal onset of one sided weakness. Affected babies may have a weak cry, find it difficult to feed and have a floppy head, neck and limbs.
(WHO, 2023)
Treatments for botulism vary depending on the source of infection as briefly described above but usually require neutralization of toxins with specific antitoxins or antibodies as well as monitoring and support of the bodily functions (such as breathing) until recovery. Most patients make a full recovery with treatment however, without prompt medical intervention the paralysis can spread to muscles responsible for the breathing function and this can be fatal in some cases. Although the treatment will not immediately reverse any paralysis already caused by the toxins, it will prevent if from getting worse. In most patients, paralysis that has occurred prior to receiving treatment will gradually improve over the following weeks or months.
(NHS, 2026)
Disclaimer: This post is for informational purposes only and is not a substitute for professional medical or food safety advice. If you have concerns about symptoms or safe canning practices, please consult a medical professional or a certified food preservation specialist immediately.
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