Do Potatoes Release Toxins and When Are They Dangerous?

November 16, 2025 •

4 min read

According to the Food Safety Information Council, all potatoes contain natural toxins called glycoalkaloids, though typically at low and harmless levels. While a staple in diets worldwide, these tubers can become a food safety concern if improperly stored or prepared, as certain conditions cause a significant increase in their toxic compounds.

Quick Summary

Potatoes naturally produce toxic glycoalkaloids, primarily solanine and chaconine, as a defense mechanism against pests. Exposure to light, physical damage, and improper storage cause levels of these compounds to rise, indicated by greening and sprouting. While toxicity is rare, it can cause gastrointestinal and neurological issues if high-level tubers are consumed.

Key Points

Glycoalkaloids are natural toxins: Potatoes contain glycoalkaloids like solanine and chaconine as a defense mechanism, normally at safe levels.
Green color signals potential danger: Greening indicates chlorophyll production due to light exposure, which also stimulates toxin synthesis in the same areas.
Sprouts are toxic: High concentrations of glycoalkaloids are found in potato sprouts and should always be removed.
Bitter taste means discard: A bitter flavor in a cooked potato is a more reliable sign of high toxin levels than color alone, and it should not be eaten.
Cooking is not a solution: Heat does not effectively destroy these toxins. Peeling is the most reliable way to remove them from contaminated parts.
Proper storage prevents toxicity: Storing potatoes in a cool, dark, and dry place away from light and other produce is the best way to prevent toxin build-up.
Discard severely affected potatoes: If a potato is very green, has extensive sprouts, or tastes bitter after cooking, it should be discarded completely.
Symptoms are mostly gastrointestinal: Ingesting high levels of potato toxins can cause nausea, vomiting, and stomach cramps, but severe poisoning is rare.

Understanding Potato Toxins: Glycoalkaloids

Potatoes are members of the nightshade family, Solanaceae, which includes tomatoes and eggplants. All plants in this family naturally produce glycoalkaloids, a class of toxic compounds that serve as a natural defense system against pests and diseases. The two main glycoalkaloids found in potatoes are alpha-solanine and alpha-chaconine.

Under normal conditions and with proper storage, the concentration of these compounds in edible potatoes is very low and poses no threat to humans. However, specific environmental and storage factors can cause a significant and dangerous increase in these toxins, making the potatoes unsafe to eat.

Factors That Increase Glycoalkaloid Levels

Light Exposure: Potatoes stored in the light will begin to produce chlorophyll, the harmless green pigment. However, the same light exposure also stimulates the production of glycoalkaloids. The greening serves as a visible warning sign of potential toxicity. The toxins are concentrated in the green skin and the area just beneath it.
Physical Damage: Bruises, cuts, and other physical injuries to the potato can trigger an increase in glycoalkaloid synthesis as a defensive reaction. The toxins tend to accumulate around the damaged areas.
Sprouting: Potato sprouts, or "eyes," contain high concentrations of solanine and chaconine. As the potato ages and begins to sprout, the toxin levels rise throughout the tuber.
Improper Storage: Storing potatoes in warm, humid conditions rather than a cool, dark, and dry place accelerates sprouting and can contribute to higher glycoalkaloid levels.

Identifying and Preventing Toxin Exposure

Recognizing the signs of elevated glycoalkaloids is key to preventing accidental poisoning. It's not just about the green color; a bitter taste is another reliable indicator of high toxicity.

What to look for:

Greening: Any potato with a green hue, especially on the skin, should be checked carefully. Generously peel away all green parts, not just the surface level.
Sprouts: Small sprouts can be cut away with a paring knife. If the sprouts are extensive or the potato is soft, the entire potato should be discarded.
Bitter Taste: If a cooked potato has a distinctly bitter or burning taste, it is a sign of high glycoalkaloid levels and should be thrown out immediately.
Rotting/Damage: Discard potatoes that are soft, shriveled, or have significant damage, as these are likely to have high toxin concentrations.

The Effect of Cooking and Processing

Contrary to popular belief, heat does not effectively destroy glycoalkaloids. Cooking methods like boiling and baking only have a minimal effect on the toxin levels, and peeling is the most effective way to remove most of the toxins.


Preparation Method	Effectiveness in Removing Glycoalkaloids	Notes
Peeling	High (25-75% reduction)	Removes the outer layers where toxins concentrate. The most effective step.
Boiling	Low-Moderate (Leaching into water)	Causes some leaching of water-soluble glycoalkaloids, but not complete removal. Do not reuse the boiling water.
Frying/Deep-Frying	Moderate (at high temperatures)	Requires temperatures above 170°C to start degradation. Not reliable for significant toxin reduction.
Microwaving	Low (Minimal reduction)	Has a minimal effect on the toxin levels.

Health Risks of Glycoalkaloid Poisoning

While serious poisoning is extremely rare, it can occur if large quantities of highly toxic potatoes are consumed. Most cases of intoxication involve mild gastrointestinal distress.

Symptoms of solanine poisoning:

Nausea, vomiting, and abdominal pain
Diarrhea
Headaches and dizziness
Burning sensation in the mouth or throat
In severe cases: fever, rapid pulse, low blood pressure, paralysis, and in very rare instances, death.

Safe Handling and Storage of Potatoes

To ensure your potatoes remain safe for consumption, proper handling and storage are crucial.

Best practices for potato storage:

Cool, Dark, and Dry: Store potatoes in a well-ventilated, dark, and cool place, such as a pantry or cellar. Temperatures between 45–55°F are ideal.
No Sunlight: Keep potatoes away from direct sunlight and artificial light to prevent greening and toxin build-up.
Avoid the Refrigerator: The low temperatures in a refrigerator can cause the potato's starch to convert to sugar, affecting taste and color. Some studies also suggest cold storage might increase toxin levels.
Separate from Other Produce: Store potatoes separately from onions, apples, and other fruits, as the ethylene gas they release can speed up sprouting.

Conclusion: Responsible Consumption is Key

Yes, potatoes contain naturally occurring toxins, but the risk to human health is minimal under normal circumstances. The toxins, primarily solanine and chaconine, increase when a potato is exposed to light, physical damage, or improper storage, leading to greening, sprouting, and a bitter taste. By generously peeling or trimming away green and sprouted parts and discarding any potato that is extensively green or tastes bitter, you can enjoy this versatile vegetable safely. Proper storage in a cool, dark, and dry place is the best preventative measure against toxin build-up. Learn more about potato varieties and their nutrient content here.

Frequently Asked Questions

If you eat a green potato, especially one with a significant green tinge, you risk consuming elevated levels of the toxin solanine, which can cause symptoms like nausea, vomiting, stomach cramps, and headaches.

Yes, peeling a green potato and generously trimming away all green flesh and sprouts can significantly reduce its solanine levels. However, if the potato still tastes bitter after cooking, it should be discarded.

Small sprouts can be cut away, and if the potato is still firm, it is likely safe to eat after trimming. However, if the potato is soft, shriveled, or has extensive sprouts, discard it entirely, as toxin levels are higher.

Cooking methods like boiling, baking, and frying are not very effective at destroying glycoalkaloids. The most effective way to reduce toxins is through peeling and generously trimming affected areas.

The initial symptoms of solanine poisoning often include gastrointestinal issues such as nausea, vomiting, diarrhea, and stomach pain. A burning sensation in the mouth or throat is another early warning sign.

Store potatoes in a cool, dark, and dry place to prevent greening and sprouting. An ideal location is a pantry or cellar, and they should be stored away from light and other produce like onions and apples.

The poisonous compounds in potatoes are called glycoalkaloids, primarily alpha-solanine and alpha-chaconine. They are natural defense chemicals produced by the plant.