What Are the Symptoms of Cassava Poisoning?

January 2, 2026 •

3 min read

Raw or improperly processed cassava contains cyanogenic glycosides that, when ingested, release toxic hydrogen cyanide, leading to cassava poisoning. This can have effects ranging from mild discomfort to severe, life-threatening complications, depending on the amount consumed and preparation method.

Quick Summary

Cyanide from improperly prepared cassava causes poisoning, with symptoms ranging from mild gastrointestinal upset to severe neurological and respiratory distress. Improper long-term exposure can lead to chronic conditions like debilitating paralysis.

Key Points

Headache and Dizziness: Mild cassava poisoning frequently begins with a headache and feeling of dizziness within hours of consumption.
Gastrointestinal Upset: Nausea, vomiting, and stomach pains are very common symptoms, especially in cases of mild poisoning.
Neurological Crisis: Severe acute poisoning can trigger neurological symptoms like convulsions, confusion, panic, and loss of consciousness.
Respiratory Failure: High doses of cyanide inhibit cellular oxygen use, leading to rapid, then slowed, breathing and eventual respiratory failure.
Konzo Paralysis: Chronic exposure to cyanide from improperly processed cassava can cause an irreversible paralytic disorder known as konzo, primarily affecting the legs.
Proper Preparation is Key: The toxic cyanogenic glycosides can be removed by peeling, soaking, and thoroughly cooking cassava.
Bitter vs. Sweet Varieties: Bitter cassava contains much higher levels of toxin and requires more extensive processing than the sweeter varieties to be safe.

The Toxic Agent in Cassava

Cassava, a staple food crop in many parts of the world, naturally contains toxic compounds known as cyanogenic glycosides, primarily linamarin. When the cassava is improperly processed or consumed raw, these compounds break down to release highly toxic hydrogen cyanide (HCN). The amount of toxin varies greatly between varieties. Bitter cassava, often used as a reserve crop due to its higher yield and drought resistance, contains significantly more cyanide than sweet cassava and requires extensive processing to be safe for consumption.

Symptoms of Mild Cassava Poisoning

In cases of mild or moderate poisoning, which often result from consuming inadequately but not completely improperly processed cassava, the symptoms are typically less severe. These can manifest slowly over several hours after consumption.

Headache and Dizziness: A general feeling of unease and a heavy head.
Gastrointestinal Distress: Nausea, vomiting, and stomach pains are common digestive issues.
Fatigue: A general sense of weakness or body aches.
Burning Sensation: Some individuals report a burning feeling in the eyes, throat, and nose.

Symptoms of Severe Acute Cassava Poisoning

Acute, severe poisoning occurs when a large amount of HCN is released into the body, overwhelming its detoxification capacity. This can be fatal if not treated immediately.

Rapid Respiration: Extremely rapid breathing is an early sign.
Neurological Disorders: This includes mental confusion, anxiety, panic, muscle spasms, convulsions, and potentially coma. The jaw may also become stiff, mimicking tetanus.
Cardiovascular Issues: A rapid, irregular pulse and a severe drop in blood pressure are critical signs.
Cyanosis: The skin may appear bluish due to tissue hypoxia, as cyanide inhibits the body's ability to use oxygen.
Respiratory and Heart Failure: Ultimately, severe poisoning can lead to paralysis of the respiratory system and heart, causing death.

The Lingering Effects of Chronic Cyanide Exposure

Long-term, low-level exposure to cyanide from relying on poorly processed cassava can lead to chronic health issues rather than a sudden toxic event.

Konzo: A paralytic disease characterized by a sudden onset of irreversible leg paralysis. It is often triggered by a peak in cyanide exposure, sometimes during times of food scarcity when processing is rushed.
Tropical Ataxic Neuropathy: A condition causing an uncoordinated gait due to damage to the spinal cord's sensory tracts.
Thyroid Dysfunction: The cyanide metabolite thiocyanate can interfere with iodine uptake by the thyroid gland, leading to goiter and cretinism in iodine-deficient areas.

Comparison of Poisoning Severity


Aspect	Mild Poisoning	Severe Acute Poisoning
Symptom Onset	Slow, often several hours after eating.	Rapid, can occur within minutes to an hour.
Gastrointestinal Effects	Mild nausea, stomach upset.	Severe nausea, vomiting, diarrhea, abdominal pain.
Neurological Impact	Dizziness, mild headache.	Severe headache, convulsions, mental confusion, coma.
Respiratory Function	Dryness in throat and nose.	Rapid, then slowed breathing, respiratory failure.
Cardiovascular Effects	Generally unaffected.	Rapid pulse, low blood pressure, heart failure.
Typical Outcome	Full recovery with supportive care (rest, hydration).	Potentially fatal without immediate, aggressive medical treatment.

Proper Cassava Preparation

To prevent cassava poisoning, proper preparation is crucial. This involves several key steps:

Peeling: The highest concentration of cyanogenic glycosides is found in the peel.
Washing: Clean peeled roots thoroughly.
Processing: The detoxification method depends on the variety.
- Boiling: For sweet varieties, boiling in water can reduce the cyanide content significantly. Changing the water during boiling is recommended.
- Soaking and Fermenting: Bitter varieties require more extensive processing. Soaking grated roots for an extended period, followed by fermentation, allows for enzymatic degradation of the toxins.
Drying: Sun-drying grated or sliced cassava is an effective way to remove volatile HCN gas.
Cooking: Always cook cassava thoroughly after processing to ensure any residual toxins are eliminated.

Conclusion

The symptoms of cassava poisoning range from mild, manageable discomfort to severe, life-threatening outcomes, and even chronic debilitating diseases with repeated exposure. The severity hinges on the amount of toxin ingested, which is determined by the cassava variety and the adequacy of its processing. Proper preparation, including peeling, soaking, and thorough cooking, is essential to render cassava safe for consumption and prevent these dangerous health consequences. By understanding the risks and following correct food safety procedures, individuals can enjoy this nutritious crop without fear of poisoning. For more information on preventing poisoning from cassava, see the CDC's report on a cyanide poisoning outbreak in Uganda: Outbreak of Cyanide Poisoning Caused by Consumption of Cassava Flour - CDC.

Frequently Asked Questions

The toxic substance in cassava is called cyanogenic glycoside, primarily linamarin. When the plant tissue is damaged, this compound breaks down to release hydrogen cyanide (HCN), a potent poison.

No, if cassava is properly peeled, soaked, and thoroughly cooked, the cyanogenic glycosides are significantly reduced and detoxified, making it safe for consumption. The risk comes from improper or incomplete preparation, particularly with the more toxic 'bitter' varieties.

Yes, children are particularly at a higher risk of severe effects from cassava poisoning due to their smaller body size and developing systems. Severe acute poisoning is common in children, and they are more susceptible to chronic effects like paralysis.

If you suspect severe cassava poisoning, immediately induce vomiting using safe methods and seek immediate medical attention by taking the person to the nearest hospital. Mild cases may improve with rest and sweet water.

The primary difference is the concentration of cyanogenic glycosides. Bitter cassava contains much higher levels and must undergo extensive processing, including soaking and fermentation, while sweet cassava can be rendered safe simply by peeling and thorough cooking.

Long-term consumption of improperly processed cassava can lead to chronic cyanide exposure, which may cause neurological disorders like konzo (paralysis of the legs) and tropical ataxic neuropathy. It can also disrupt thyroid function.

Yes, eating inadequately processed cassava on an empty stomach can increase the risk of severe acute poisoning. Children and infirm individuals are particularly vulnerable under these circumstances.