How To Avoid Botulism When Canning At Home

Avoid health risks during the canning process
home canned product displayed on shelves

Canning your own fruits and vegetables at home can be very enjoyable and has many benefits. But it can also bring an increased risk for foodborne illness.

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Although it’s a rare occurrence, botulism is generally associated with improper home canning, but may still be found in some consumer food products. It’s a serious illness that paralyzes muscles and can even lead to death.

Botulism is caused by the presence of a nerve toxin from the bacterium Clostridium botulinum — which does have some medical uses outside of being consumed. But if this toxin contaminates your food and is digested it can cause serious symptoms and side effects, according to registered dietitian Laura Jeffers, MEd, RD, LD.

“Unfortunately, something as enjoyable as canning can be very dangerous if you don’t do it properly or if you don’t know what to look for in canned goods you buy,” she says. 

Types of botulism

There are three main forms of botulism infection that occur naturally, generating toxic spores when food is not properly prepared — infant botulism, wound botulism and food-borne botulism.

  1. Infant botulism is the most common form and affects children younger than 12 months. An intestinal infection of botulinum spores causes infant botulism, which mainly affects the nervous system. These spores are common and can be found in many foods such as honey, milk and some juices. Jeffers points out that you shouldn’t feed infants honey until after their first birthday. Also make sure any milk, juices or food products have been pasteurized or thoroughly cooked.
  2. Foodborne botulism can affect anyone and generally springs from improper home-canning procedures for foods of all sorts and then eating the food that contains it.
  3. Wound botulism is rare and occurs when the botulinum toxin infects an existing wound.

How you get it

Botulism doesn’t spread from person to person like the common cold, Jeffers says.

“You can only contract foodborne botulism for example by eating contaminated food that carries the botulinum toxin,” she says. “These have usually been home-canned, home-bottled or poorly preserved.”

Home-canned foods with low acid content such as asparagus, green beans, beets and corn can easily become infected with botulism spores if you don’t follow proper canning methods.

Other foods can be risky even if they’re handled by large manufacturers.

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“Unusual problems involving chopped garlic in oil, canned cheese sauces, chili peppers, tomatoes, carrot juice and baked potatoes wrapped in foil have all been cited in botulism cases,” Jeffers says. There are also many other foods that need to be properly refrigerated after any handling or preparation. You can check the U.S. Department of Agriculture for a comprehensive list of additional food safety guidelines.

How to avoid botulism

The only way to avoid botulism is to avoid eating contaminated food.

“And the only way to avoid food contamination in your own home is to keep foods refrigerated, throw out expired food products, and very carefully and properly follow the steps to can your food,” Jeffers adds.

The U.S. FDACDC and National Center for Home Food Preservation offers detailed and proper techniques for canning and food safety guidance.

In addition to those guidelines remember these important tips when you’re canning at home:

  • If you can or bottle your own foods you want to be sure to follow strict hygienic procedures. Use a pressure canner or cooker to thoroughly cook – or pasteurize – your food. 
  • Refrigerate any foods that use oils infused with garlic or herbs. Keep potatoes baked in foil hot until they’re served or refrigerate them. Otherwise, the lack of oxygen inside the foil can allow bacteria to multiply and produce more toxin.
  • To kill C botulinum spores set your pressure cooker to 116°C. You need to cook foods until their internal temperature is 85°C for 10 minutes.
  • Consider boiling homemade canned food for 10 minutes before you eat it. It’s an important extra step to ensure the food is toxin-free before it hits your digestive tract.
  • If a can or bottle has a bulging lid don’t eat the food inside, as this can be a sign of contamination. Throw it away immediately or return it unopened to the store where you bought it. 
  • Never eat any food that smells funny, foul, even slightly “off” or doesn’t smell the way it normally should.

Signs to watch for

“According to the Centers for Disease Control and Prevention, foodborne botulism symptoms generally show up between 12 and 36 hours after you eat a food carrying the toxin,” Jeffers says. 

Sometimes the signs can show up as quickly as six hours or as late as 10 days. Generally the more quickly the symptoms appear, the more severe the case will be.

The main signs of food-borne botulism include:

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  • Difficulty swallowing or speaking.
  • Dry mouth.
  • Facial weakness (throughout the face).
  • Blurred or double vision.
  • Drooping eyelids.
  • Difficulty breathing.
  • Nausea, vomiting and abdominal cramps.
  • Paralysis.

In infants symptoms of botulism can also include: 

  • Constipation.
  • Poor feeding.
  • Excessive sleepiness.
  • Poor reflexes.

Treatment requires hospitalization

In some cases, doctors will need to induce vomiting or use enemas to cleanse your intestinal tract of any remaining botulism-laced food.

If you’re affected, you’ll likely need hospital care. Your treatment may include antitoxins to prevent or help you recover from respiratory failure and paralysis.

Doctors put patients with severe cases on a ventilator and prescribe intensive medical and nursing care during recovery.

Outbreaks are rare

Widespread occurrences of botulism are rare. Though uncommon, outbreaks can be a public safety concern because many people can be infected by the same contaminated foods.

“Generally these outbreaks will make their way to the public through multiple news sources and will offer specific brand or product information along with locations or sources of the outbreak if they’re available,” Jeffers says. 

“If you’re experiencing symptoms or think you may have ingested contaminated food, see your doctor immediately.”

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