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How do you know if you ate something with botulism?

Botulism is a rare but potentially fatal illness caused by toxins produced by the bacterium Clostridium botulinum. There are three main types of botulism: foodborne botulism, wound botulism, and infant botulism. Foodborne botulism occurs when a person ingests the botulinum toxin by eating contaminated food. Botulism toxin is odorless and colorless, so you can’t detect it by smelling or looking at food. The most common sources of foodborne botulism are home-canned foods that were not processed correctly. However, the toxin can also be found in foods that were produced commercially and improperly processed. So how do you know if you ate something contaminated with the botulism toxin?

Symptoms of Foodborne Botulism

The signs and symptoms of foodborne botulism generally begin 12 to 36 hours after ingesting the toxin. However, they can appear as early as 6 hours after exposure or as late as 10 days. The further the food traveled down the intestinal tract before the toxin was absorbed, the longer the incubation period. The initial symptoms include:

  • Double vision, blurred vision, drooping eyelids
  • Slurred speech
  • Difficulty swallowing
  • Dry mouth
  • Muscle weakness that begins in the shoulders and upper arms, moving down to the lower arms, thighs, calves, toes, abdominals, back, and neck muscles

As botulism progresses, symptoms become more severe and can include:

  • Paralysis of the arms, legs, trunk, respiratory muscles
  • Life-threatening paralysis that can cause respiratory failure and death unless assistance with breathing (mechanical ventilation) is provided

In foodborne botulism cases, gastrointestinal signs like nausea, vomiting, abdominal cramps, and diarrhea are uncommon since the toxin is absorbed into the bloodstream from the intestines before it can cause gut irritation. Infant and wound botulism cases are more likely to have gastrointestinal symptoms.

When to Seek Medical Care

You should seek immediate medical care if you experience any symptoms of botulism poisoning. Even if signs are mild at first, botulism is a medical emergency that can quickly become life-threatening. Go to an emergency room and let doctors know you suspect botulism so antitoxins can be administered as soon as possible. The antitoxins will not reverse any paralysis that has already occurred, but it can stop the progression of toxins and prevent further paralysis.

It’s also important to alert public health authorities right away when botulism is suspected so the source can be identified and more people do not become exposed.

Diagnosing Botulism

Doctors may suspect botulism based on a patient’s symptoms, particularly bilateral cranial nerve palsies (affecting muscles of the face and eyes) and descending muscle weakness. However, there are other conditions like Guillain-Barre syndrome, stroke, and myasthenia gravis that can have similar signs. Tests that can help confirm botulism include:

  • Brain wave test (EEG) – This measures electrical activity in the brain, which is typically slow in botulism patients.
  • Spinal fluid test – A lumbar puncture obtains spinal fluid to check for the botulism toxin.
  • Nerve conduction studies – Small electric shocks are applied to nerves to measure muscular response, which is reduced in botulism.
  • Blood tests – These can detect toxins in the bloodstream.
  • Stool or enema samples – Checked for presence of botulism bacteria.
  • Biopsy – In wound botulism, a biopsy of infected tissue may be done.

Identifying botulism early is key so antitoxin treatment can be started right away. Doctors may treat presumptively with antitoxins even before confirmatory tests if botulism is strongly suspected.

Finding the Contaminated Food Source

Public health and food safety authorities will work to identify the source of the contaminated food that caused an outbreak of botulism. This involves extensive detective work interviewing patients, obtaining food histories, collecting samples of unfinished food for laboratory testing, and tracing foods back through the distribution chain. Being able to find the culprit food can prevent more people from being poisoned. Botulism fact sheets advise patients to save any leftover foods in their refrigerator in sealed containers in case investigators need to test them.

Foods Most Commonly Associated with Botulism

Any food can potentially be contaminated with botulinum spores and allow toxins to develop. However, some types of foods account for a large percentage of botulism cases:

  • Home canned vegetables, fruits, meats, fish
  • Homemade baked potatoes wrapped in aluminum foil
  • Garlic stored in oil
  • Sausages and smoked fish
  • Sealed food containers with low oxygen

The following table provides details on the specific foods linked to botulism outbreaks and why they can be risky:

Food Botulism Risk Factors
Home canned goods Improper canning methods allow spores to survive. Toxins form as bacteria grow in moist, low oxygen environment inside jar.
Baked potatoes in foil Spores can survive baking. Wrapping in foil provides warm, anaerobic environment for toxin production.
Garlic in oil Spores thrive in oxygen-free environment under oil. Toxins form as garlic ferments.
Smoked fish Toxins can form if fish is not fully cooked/smoked to destroy spores and then is vacuum sealed.
Sausages Spores not fully destroyed before stuffing sausage may produce toxins during anaerobic fermentation.
Sealed foods Vacuum sealing or tightly wrapping foods can create anaerobic environment for spores to grow.

Preventing Foodborne Botulism

You can reduce your risk of foodborne botulism by taking proper precautions when preparing, handling, and storing foods. Recommendations include:

  • Carefully follow established home canning procedures. Use pressure canner, proper processing times for high acid and low acid foods.
  • Never eat home jarred foods if signs of spoilage like mold, off smells, spurting liquid, bulging lid.
  • Refrigerate leftover baked potatoes quickly, don’t seal in foil.
  • Avoid storing garlic or herbs immersed in oil. Instead, freeze herb purees in ice cube trays with broth or oil.
  • Cook smoked fish and meat thoroughly to internal temperature of 165°F.
  • Avoid eating raw smoked fish or meat.
  • Discard bulging or leaking vacuum sealed packages.
  • Boil home canned vegetables for 10 minutes before eating to destroy toxins.

Commercially processed canned and packaged foods very rarely cause botulism. Manufacturers follow stringent regulations for sterilization and packaging. However, on the rare chance a contaminated product slips through, consumers should carefully examine packages before buying and consuming:

  • Do not eat from bulging, cracked, or leaking cans.
  • Do not buy products with torn, damaged, or missing vacuum seals.
  • Notify store management about damaged packages.

If you purchase a product that later is recalled due to possible botulism contamination, do not eat it. Follow recall instructions on proper disposal and if you consumed any, seek medical attention immediately.

Treatment for Botulism

Treatment focuses on supporting respiratory function and neutralizing unbound botulism toxin. This includes:

  • Antitoxins – Injections of antitoxins such as BabyBIG bind circulating toxins to prevent progression of illness.
  • Ventilation – Using a ventilator to support breathing, weeks or months may be needed until neuromuscular function returns.
  • Tube feeding – High calorie formulas delivered via feeding tube since patients have trouble swallowing.
  • Medications – Laxatives, eye drops, antibiotics, pain relievers may be prescribed.
  • Physical therapy – Gradually building muscle strength back once illness stabilizes.

With intensive care, the case fatality rate for foodborne botulism is about 5-10%. But full recovery from paralysis and fatigue caused by botulism can be prolonged, taking weeks, months or years depending on severity.

Long-Term Outcomes

Survivors of botulism poisoning may face long-term effects even after the botulism toxin is neutralized and muscles regain function. Ongoing problems can include:

  • Fatigue
  • Shortness of breath
  • Difficulty swallowing
  • Dry mouth
  • Joint and muscle pain

Patients who required weeks or months of mechanical ventilation can have reduced lung capacity. Physical and occupational therapy are often needed to rebuild muscle mass lost during the paralysis phase of illness. Some people report depression or post-traumatic stress after an extended ICU stay and recovery process.

Outlook for Botulism Patients

With prompt diagnosis and treatment, most patients will survive an episode of foodborne botulism. However, due to the long paralysis and rehabilitation period, it can be months before they achieve a full recovery. Early administration of antitoxins helps reduce severity by neutralizing toxins before extensive damage occurs. Close monitoring of respiratory status is crucial in the first 1-3 weeks when paralysis rapidly progresses. If ventilation support is provided during this critical phase, most patients improve as the toxin clears their body naturally.

In general, the long-term outlook is good for survivors of botulism poisoning as long as no permanent damage occurred before treatment. Patients who receive antitoxins within 24 hours of symptom onset typically have shorter illness and better outcomes. Still, recovery takes time depending on factors like a patient’s age, underlying health conditions, and illness severity. With proper follow-up care, most botulism patients can eventually regain their previous functional status. However, it’s important to seek medical evaluation for any lingering symptoms like fatigue, swallowing difficulties, breathing issues or emotional problems so appropriate supportive treatment can be provided.


Botulism is a rare but life-threatening condition that must be treated as a medical emergency. Seek immediate medical care if signs of botulism poisoning occur, like blurred vision, muscle weakness, difficulty speaking or swallowing, or shortness of breath. Make sure doctors know that foodborne botulism is suspected so antitoxin treatment can be started right away and authorities can test any leftover food for contamination. Although botulism recovery is slow and may take months, intensive supportive care and early antitoxins can greatly reduce complications. Following proper home canning and food handling procedures reduces your risk of exposure to the botulinum toxin. While botulism can have long-lasting effects, most patients regain function with rehabilitation and have a good long-term outcome.