Human Health

Botulism and home canning

August 10, 2012, 11:55 am
Source: Centers for Disease Control and Prevention
Content Cover Image

Source: Centers for Disease Control and Prevention.

Home canning is an excellent way to preserve garden produce and share it with family and friends, but it can be risky or even deadly if not done correctly and safely.

Home Canning and Botulism

It's summer, and home gardeners may already be harvesting—or thinking about harvesting—the delicious produce they've been growing this year. Food gardening and home canning are becoming increasingly popular in the United States. According to one survey, 1 in 5 U.S. households can their own food, and 65% of those households can vegetables.

If canning is done improperly, the vegetables you worked so hard to grow, harvest, and preserve could become contaminated with germs that cause serious illness. In fact, a study shows that many home canners are not aware of the risk of botulism, a rare and potentially fatal foodborne illness that has been linked to improperly canned food. By knowing about the risks and learning the safe way to can, you can protect yourself, your family, and others when you share your home-canned goodies.

Home-canned vegetables are the most common cause of botulism outbreaks in the United States. From 1996 to 2008, there were 116 outbreaks of foodborne botulism reported to CDC. Of the 48 outbreaks that were caused by home-prepared foods, 18 outbreaks, or 38%, were from home-canned vegetables. These outbreaks often occur because home canners did not follow canning instructions, did not use pressure cookers, ignored signs of food spoilage, and were unaware of the risk of botulism from improperly preserving vegetables.

For more information, see:

Botulism, rare but deadly

Botulism is a rare, but serious illness caused by a germ called Clostridium botulinum. The germ is found in soil and can survive, grow, and produce toxin in a sealed jar of food. This toxin can affect your nerves, paralyze you, and even cause death. Even taking a small taste of food containing this toxin can be deadly.

Botulism is a medical emergency. If you have symptoms of foodborne botulism, seek medical care immediately. 

Symptoms may include the following:

  • Double vision
  • Blurred vision
  • Drooping eyelids
  • Slurred speech
  • Difficulty swallowing
  • Dry mouth
  • Muscle weakness

Keep your vegetables safe from contamination

Here are some tips to keep your canned vegetables safe and keep them from spoiling.

Use proper canning techniques

Make sure your food preservation information is always current with up-to-date, scientifically tested guidelines. Don't use outdated publications or cookbooks, even if they were handed down to you from trusted family cooks.

You can find in-depth, step-by-step directions from the following sources:

Make your home-canned vegetables safe

  • Use a pressure canner or cooker.
  • Be sure the gauge of the pressure canner or cooker is accurate.
  • Use up-to-date process times and pressures for the kind of food, the size of jar, and the method of packing food in the jar.

Use the right equipment for the kind of foods that you are canning.

Use a pressure canner or cooker. Pressure canning is the only recommended method for canning vegetables, meat, poultry, and seafood. The germ bacterium that causes botulism is destroyed when these foods are processed at the correct time and pressure in pressure canners or cookers. Do not use boiling water canners because they will not protect against botulism poisoning.

Any food that may be contaminated with the germs that cause botulism should be thrown out. If you suspect that you have contaminated food, see "Safely dispose home-canned foods."

caption Source: Centers for Disease Control and Prevention. Protect yourself from botulism: When in doubt, throw it out!

  • Any food that may be contaminated with the germs that cause botulism should be thrown out. If you suspect that you have contaminated food, see "Safely dispose home-canned foods."
  • Never taste the product to determine if it is safe. Do not taste or eat foods from containers that are leaking, have bulges or are swollen, or look damaged, cracked, or abnormal.
  • When you open a jar of home-canned food, thoroughly inspect the product. Do not taste or eat foods that are discolored, moldy, or smell bad.
    Do not use products that spurt liquid or foam when the container is opened.
Inspect your home-canned foods before consuming.
  • Suspect contamination if
    • The container is leaking, bulging, or swollen
    • The container looks damaged, cracked, or abnormal
    • The container spurts liquid or foam when opened
    • The food is discolored, moldy, or smells bad
  • Don’t open or puncture any unopened cans, commercial
    or home-canned, if you suspect contamination.
Safely dispose of food and cans that may be contaminated

If a home-canned food that may be contaminated is spilled, wipe up the spill using a dilute bleach solution (1/4 cup bleach for each 2 cups of water).

Online Resources

General Information

Home Canning




(2012). Botulism and home canning. Retrieved from