How do I know if my potatoes have solanine?

November 12, 2025 •

5 min read

According to the National Capital Poison Center, potatoes contain natural toxins called glycoalkaloids, including solanine, which can increase to unsafe levels under certain conditions. Knowing how do I know if my potatoes have solanine is crucial for preventing illness, as this natural defense mechanism becomes toxic when exposed to light or physical damage.

Quick Summary

This guide explains how to identify the presence of solanine in potatoes using visual cues like green skin, checking for sprouts, and tasting for bitterness. It details when to discard a potato and how to store them properly to prevent the formation of this toxin.

Key Points

Check for green skin: Green patches on a potato indicate chlorophyll, which signals that higher levels of the toxin solanine are also likely present.
Look for sprouts and damage: Sprouts, or “eyes,” and physical damage trigger higher solanine production; discard potatoes with excessive sprouts or bruising.
Trust your taste buds: A bitter flavor or a burning sensation in the mouth is a strong indicator of high solanine levels, and such potatoes should not be eaten.
Prioritize proper storage: Store potatoes in a cool, dark, and well-ventilated space to prevent the light exposure and warm temperatures that cause solanine production.
Avoid relying on cooking: Cooking does not effectively eliminate solanine, so peeling and trimming green spots is the only way to potentially salvage a mildly affected potato.
When in doubt, throw it out: If a potato shows extensive greening, significant sprouting, or tastes bitter, the safest approach is to discard it completely.

Visual indicators of solanine in potatoes

One of the most obvious signs that a potato may contain high levels of solanine is a green tinge under the skin. While the green color itself comes from chlorophyll, an harmless compound, its presence signals that the potato has also been producing solanine as a protective response to light exposure. This means that when you see green, the toxic solanine is likely present, especially concentrated in the green areas and just beneath the surface. For potatoes with darker skins, you can use a knife to scrape a small area and check for green discoloration.

Another clear visual sign is the presence of sprouts or "eyes." Solanine concentrations are highest in the sprouts and the area immediately surrounding them. Even if the potato skin itself isn't green, sprouts are a strong indicator that the tuber is past its prime and accumulating toxins. A shriveled or bruised appearance can also point to high solanine levels, as physical damage can trigger the potato's defense mechanisms and increase toxin production.

The taste test: an important warning signal

In addition to visual cues, the taste of a potato is a reliable indicator of solanine content. High levels of this glycoalkaloid can produce a distinctly bitter flavor or a burning sensation in the mouth and throat. It is important to note that you should not continue eating a potato if you notice this bitterness. Most people will stop eating a potato with a bitter taste, which is a natural defense against consuming harmful amounts of the toxin. Cooking does not eliminate solanine, so even a cooked potato can still taste bitter and should not be consumed if it does.

How to tell if a potato tastes bitter

Cut and smell: Before cooking, slice a small piece. A strong, earthy, or slightly unpleasant smell can be an early indicator.
Raw taste test: Carefully taste a tiny piece of the peeled, raw potato. If you notice any bitterness or a burning sensation, discard it immediately. Never consume raw potato in large amounts.
Post-cooking taste: If you cooked a potato that had some green spots, taste a small portion first. If it's bitter or causes a burning feeling, throw the entire dish away.

Comparison: Safe vs. solanine-heavy potatoes


Feature	Safe Potato	Potato with high solanine
Appearance	Uniformly colored skin, firm texture, no greening	Green patches, especially under the skin; shriveled or soft spots; numerous sprouts
Sprouts/Eyes	Few or no sprouts	Excessive sprouts, especially if they are large and green
Taste	Mild, earthy potato flavor	Distinctly bitter taste, and can cause a burning sensation in the mouth
Odor	Earthy, fresh potato smell	Strong, potentially unpleasant odor
Texture	Firm and smooth	Soft, wrinkled, or shriveled areas; can feel rubbery or mushy

Proper handling and storage to prevent solanine

Solanine production is triggered primarily by light exposure, physical damage, and warm temperatures. Therefore, proper storage is the most effective way to prevent your potatoes from accumulating this toxin.

Store in a cool, dark place: Ideal storage conditions are a dark pantry, cupboard, or root cellar, where temperatures are consistently cool (ideally 45-50°F / 7-10°C). Storing them in the refrigerator is too cold and can alter their flavor and texture.
Use a breathable container: Store potatoes in a paper bag, mesh bag, or cardboard box to allow for proper air circulation and protect them from light. Avoid using plastic bags, which trap moisture and speed up spoilage.
Keep away from other produce: Storing potatoes near onions or apples can accelerate sprouting due to the gases they release. Keep them separate to prolong their shelf life.
Don't wash before storing: The dirt on potatoes provides a natural layer of protection. Only wash them right before you plan to use them.

The risks and what to do

While solanine poisoning is rare, it is important to take precautions. The toxin is primarily a neurotoxin that can cause gastrointestinal and neurological symptoms, including nausea, vomiting, abdominal pain, headaches, and diarrhea. In very rare and severe cases involving a large quantity of highly toxic potatoes, more serious symptoms or even death can occur, though most exposures resolve with no long-term issues.

If you find a potato with green spots or sprouts, the safest course of action is to discard it. While peeling and cutting away small green areas can reduce the toxin, it's not foolproof, especially if the greening is extensive or the potato tastes bitter. Children are more susceptible to solanine's effects due to their smaller body size, so extra caution should be taken with their food. If you suspect you or someone else has consumed a toxic potato, contact a poison control center for guidance.

Conclusion

Ultimately, a combination of visual inspection and taste is the best defense against consuming potatoes high in solanine. The appearance of green patches, excessive sprouts, or a soft, shriveled texture are clear red flags. Most importantly, if a potato tastes bitter or causes a burning sensation, it should be discarded immediately, regardless of its appearance. Proper storage in a cool, dark, and well-ventilated space is key to preventing solanine production in the first place, ensuring your potatoes remain safe and delicious. When in doubt, it is always safest to throw it out.

A note on cooking and removing solanine

Contrary to popular belief, cooking methods like boiling, frying, and baking do not effectively destroy solanine. Studies have shown that boiling can remove only minimal amounts of the toxin. Peeling the skin and trimming away green or sprouted parts is the most effective way to reduce solanine levels, but is not guaranteed to remove all of it, particularly if the concentration is very high. For the highest level of safety, discard any potato with extensive greening, significant sprouting, or a bitter taste.

For further reading on potato safety from a reputable source, consult the resources available through the US Department of Agriculture.

How to properly dispose of high-solanine potatoes

Disposing of high-solanine potatoes is just as important as identifying them. Do not feed them to pets or livestock, as animals are also susceptible to solanine poisoning. The safest method of disposal is to throw them in the trash, where they cannot be accidentally consumed. Alternatively, you can compost them if you are sure they won't be eaten. For gardeners, a very green potato can also be planted to produce new plants, but this should be done with care to prevent any accidental consumption.

Frequently Asked Questions

Yes, if the green discoloration is minimal and only on the surface, peeling it and cutting away the green parts and any sprouts can make the potato safe to eat. However, if the greening is extensive or the potato tastes bitter, it is best to discard the entire potato.

No, cooking methods like boiling, frying, or baking do not effectively destroy solanine. The toxin is heat-stable, so heat treatment is not a reliable method for removing it from affected potatoes.

A potato with high solanine content will taste distinctly bitter and can cause a burning sensation in the mouth or throat. This bitter taste is a reliable warning sign that it should not be consumed.

Potatoes turn green when they are exposed to light. The light causes the potato to produce chlorophyll, the green pigment found in plants. This same exposure also causes an increase in solanine, a natural toxin.

Symptoms of solanine poisoning can include nausea, vomiting, abdominal pain, diarrhea, headaches, and dizziness. More severe, but rare, cases can cause neurological issues.

No, you should never feed green or sprouted potatoes to your pets or livestock. Animals are also susceptible to solanine poisoning, and consuming them could make them seriously ill.

Store potatoes in a cool, dark, and well-ventilated area like a pantry or cupboard. Keeping them away from light and in a breathable container, such as a paper bag, will help prevent them from turning green.

While removing the sprouts can reduce some of the concentrated solanine, the potato may still contain higher-than-normal levels throughout. It's safest to discard potatoes that have sprouted significantly, especially if they also appear green or feel soft.

While extremely rare, fatal cases of solanine poisoning have been reported after consuming large quantities of severely toxic potatoes. Most cases involve milder symptoms that resolve on their own, but it is a serious risk that should be avoided.