Botulism: Symptoms, Causes & Diagnosis

Botulism (or botulism poisoning) is a rare but very serious illness caused by the bacteria Clostridium botulinum. Symptoms typically include weakness, blurred vision, double vision, slurred speech, dry mouth, muscle weakness, and difficulty swallowing. The toxin shuts down nerve function that control the muscles needed to breathe. In extreme cases, botulism can be fatal.

A toxin-producing strain of C. botulinum was first identified in 1929. The bacteria’s botulinum toxin paralyzes the nerves that control the muscles needed to breathe. Once that happens, the sufferer has trouble breathing and may die within a few hours.

Traces of this toxin were used to kill the beetles that caused the Black Death (the bacterium was spread from human to human during the medieval period).


Symptoms of botulism can appear from six hours to 10 days after eating contaminated food. The toxin can enter the body through eating contaminated food or through the skin while preparing or consuming it.

Symptoms include weakness, dizziness, double vision, and trouble with speaking or swallowing. The illness is fatal in 15 percent of cases if not treated.

Anyone with the following symptoms should seek emergency medical attention:

  • confusion
  • a dry mouth
  • double vision
  • a dry mouth with constricted pupils
  • slurred speech
  • difficulty swallowing
  • fever of over 38.5 C
  • watery or foam-like stool
  • enlarged pupils
  • muscle weakness
  • weight loss
  • twitching muscles
  • wheezing
  • reaction to cold or light
  • weakness
  • tremor
  • weakness or paralysis on one side of the body

What is botulism?

Botulism is a rare illness caused by a toxin found in food, contaminated alcohol, or even improperly prepared products, such as home made soup.

Causes of botulism

contaminated food

There are many causes for Botulism which include:

  • Ingestion of contaminated food
  • Eating of spoiled or contaminated food
  • Drinking of untreated water or water-contaminated foods
  • Eating of material containing Clostridium botulinum
  • Ingestion of contaminated mushrooms
  • Possibly a combination of the above.

contaminated water

What are the common symptoms of botulism?

Symptoms may not be apparent for a few hours to weeks after eating contaminated food. The symptoms include double vision, blurred vision, drooping eyelids, slurred speech, blurred vision, dry mouth, and muscle weakness.

How does botulism spread?

People who are sick with botulism may not have symptoms. People who have food borne illness — such as botulism — can spread it to anyone they come into contact with.

If a person has not eaten food contaminated with the toxin, they will not have symptoms, the CDC says. However, they can spread it to anyone they come into contact with. The person can then get sick and develop botulism.

“For some foods, such as home-canned foods, the risk of contamination does not increase with age. There is no known medical reason why this is the case, but it’s possible that high dietary intake of vitamin C, or long-term vitamin C supplementation, helps protect against the disease,” according to the CDC.

How is botulism treated?

A healthcare provider can diagnose the illness and begin treating the symptoms immediately. They will likely prescribe an antifullness drug that’s often given with an antacid, such as Alka-Seltzer Plus.

Treatment options for botulism include intravenous fluids, antipyretic medication and supportive therapy. In severe cases, hospitalization may be required.

Patients can also have a related condition called infant botulism, in which symptoms begin between seven and 14 days after ingesting contaminated food or drinks. Infants are at a higher risk of serious illness because they have a thinner than usual oral barrier and their body temperature is lower than an adult’s.

Infants should receive appropriate treatment, including intravenous fluids and antibacterial treatment. The treatment is intended to limit the spread of the toxins.

How long does it take to recover from botulism?

Most people recover within several weeks, according to the Mayo Clinic. However, the illness is more likely to be fatal for people older than 50 years or those with weakened immune systems.

In some cases, a person may need long-term care in an inpatient rehabilitation facility for six months or more to regain their strength.

How is botulism prevented?

The CDC recommends that people not eat or drink food that is not prepared at home.

The agency also advises that people follow safety and food preparation recommendations for preparing home-cooked food, including:

  • Cooking at the correct temperature.
  • Pressing the lid firmly on cans before opening.
  • Safely opening cans with metal tongs or a can opener.
  • Washing hands with soap and water, or using an alcohol-based sanitizer, right after handling the food.
  • Avoiding exposing to large amounts of pickled vegetables and unpasteurized dairy products.