What Are the Side Effects of Eating Green Tomatoes? Your Guide to Unripe Tomatoes

November 27, 2025 •

4 min read

Unripe green tomatoes contain higher levels of glycoalkaloids compared to ripe red tomatoes. While a small amount is unlikely to cause harm, understanding the potential side effects of eating green tomatoes is important for safe consumption, as large quantities can lead to digestive discomfort.

Quick Summary

Unripe green tomatoes contain glycoalkaloids, like tomatine and solanine, which can cause gastrointestinal distress if eaten in large amounts. Sensitivity and proper preparation are key considerations for safety.

Key Points

Glycoalkaloids: Unripe green tomatoes contain higher levels of natural toxins called glycoalkaloids, primarily tomatine and solanine, which are reduced as the fruit ripens.
Digestive Distress: Ingesting large amounts of unripe green tomatoes can lead to gastrointestinal side effects like nausea, vomiting, abdominal cramps, and diarrhea.
Nightshade Sensitivity: Some individuals with nightshade sensitivity may experience adverse reactions such as joint pain or skin rashes, even with small amounts.
Moderation and Cooking: Consuming green tomatoes in moderation and cooking them thoroughly, or fermenting them, can help mitigate the risk of adverse effects.
Distinguish Varieties: It is important not to confuse unripe green tomatoes with varieties like 'Green Zebra' that are green when fully ripe and safe to eat raw.
Avoid Foliage: The leaves and stems of tomato plants contain the highest concentration of toxins and should never be consumed.

The reputation of green tomatoes as potentially toxic stems from the fact that tomato plants belong to the nightshade family. This family of plants, which also includes potatoes and eggplants, produces natural compounds called glycoalkaloids as a defense mechanism against pests. For tomatoes, the primary glycoalkaloid in the unripe fruit is tomatine, along with trace amounts of solanine. As the tomato ripens and turns red, the concentration of these alkaloids decreases significantly. The leaves and stems of the tomato plant, however, contain a much higher concentration of these toxins and should never be consumed.

Gastrointestinal Discomfort

The most common side effect of eating a large quantity of unripe green tomatoes is gastrointestinal distress. The bitterness and mild toxicity of the glycoalkaloids can cause discomfort in many individuals. Symptoms may include:

Nausea
Vomiting
Diarrhea
Abdominal pain and cramps

These symptoms are typically mild and temporary, resolving on their own. The body's natural sensitivity to the bitter taste and potential distress often prevents a person from consuming enough to cause serious harm. For a significant toxic reaction to occur, an adult would need to consume an extremely large amount of unripe tomatoes, an amount that would likely be unpalatable.

Potential for Nightshade Sensitivity

Some individuals have a sensitivity or intolerance to nightshade vegetables, which includes tomatoes, peppers, and eggplants. For these people, even the lower level of alkaloids in green tomatoes might trigger a reaction. Symptoms of nightshade sensitivity can extend beyond simple digestive issues and may include:

Joint pain
Inflammation
Skin rashes

If you have a known nightshade sensitivity, consuming any form of tomato, especially unripe varieties, should be approached with caution. Consulting a healthcare provider is recommended if you suspect a sensitivity.

Aggravation of Acid Reflux

Tomatoes, both ripe and unripe, are naturally acidic due to the presence of malic acid and citric acid. For individuals prone to or suffering from gastroesophageal reflux disease (GERD) or other acid reflux conditions, eating green tomatoes can exacerbate symptoms. The combination of acidity and the presence of glycoalkaloids can be particularly irritating to a sensitive digestive system.

Allergic Reactions

Although rare, some people have a genuine allergy to tomatoes. This can manifest as an allergic reaction with symptoms ranging from mild itching and swelling of the mouth to more severe issues like hives or even anaphylaxis. While such reactions are uncommon, they are a possibility for a very small portion of the population.

How to Safely Consume Green Tomatoes

For those who enjoy the tangy flavor of unripe green tomatoes, moderate consumption and proper preparation are key. Here are some tips for enjoying them with minimal risk:

Moderation is essential: The risk of digestive upset from glycoalkaloids increases with the amount consumed. Enjoy green tomatoes in small quantities rather than large, regular servings.
Cook thoroughly: Cooking green tomatoes helps to break down and reduce some of the glycoalkaloid content. This is why classic dishes like fried green tomatoes are a popular and relatively safe way to enjoy them.
Fermentation: Fermenting green tomatoes can significantly reduce the level of glycoalkaloids by up to 50%. This process also introduces beneficial probiotics.
Distinguish varieties: Not all green tomatoes are unripe. Varieties like 'Green Zebra' are green even when ripe. Ripe green tomatoes are safe and have a different flavor profile. You can tell the difference by firmness; ripe green tomatoes will soften like a ripe red tomato.
Avoid leaves and stems: The foliage of the tomato plant contains the highest concentration of toxic alkaloids. Always discard the leaves and stems.

Comparison of Green Tomato Types

To clear up confusion, here is a comparison of truly unripe green tomatoes and ripe green tomato varieties.


Feature	Unripe Green Tomato	Ripe Green Tomato (e.g., Green Zebra)
Appearance	Pale, uniform green color; very firm.	Green skin with darker green, yellowish, or reddish stripes; soft when ripe.
Flavor	Tart, acidic, and slightly bitter.	Tangy and sweet, with less acidity.
Glycoalkaloid Content	Higher levels of tomatine and solanine.	Negligible, very low levels, similar to ripe red tomatoes.
Best Consumption	Cooked or fermented, and in moderation.	Can be eaten raw or cooked, in salads or salsas.
Texture	Hard and very firm.	Softens as it ripens, similar to a red tomato.

What to Do If You Feel Unwell

If you experience severe digestive issues like persistent vomiting, intense stomach pain, or diarrhea after eating green tomatoes, it is wise to seek medical advice. While serious poisoning is highly unlikely, these symptoms can indicate a heightened sensitivity or another underlying issue. Most mild cases of discomfort will pass on their own with no intervention needed.

Conclusion

Ultimately, eating green tomatoes in moderation, and especially when cooked or fermented, is generally safe for most people. The primary risk is from the higher concentration of glycoalkaloids, which can cause temporary digestive upset if consumed in large quantities. Understanding the distinction between unripe tomatoes and naturally green varieties, coupled with proper preparation, ensures you can enjoy this versatile fruit with peace of mind. For those with nightshade sensitivities, caution and moderation are especially advised.

One helpful resource for further reading on nightshade sensitivity is from the Cleveland Clinic: Does A Nightshade-Free Diet Help With Pain?

Frequently Asked Questions

No, not all green tomatoes are poisonous. There is a distinction between unripe tomatoes and certain varieties, like 'Green Zebra,' that are naturally green even when ripe. Only unripe tomatoes have a higher concentration of glycoalkaloids, which can be toxic in very large amounts.

The main toxins in unripe green tomatoes are glycoalkaloids, predominantly tomatine and a smaller amount of solanine. These compounds are part of the plant's natural defense system and their levels decrease as the tomato ripens.

Yes, cooking can help. Frying, baking, or stewing green tomatoes can reduce the levels of glycoalkaloids. Fermenting them is also a highly effective method for reducing the toxin content.

For an adult, serious harm from glycoalkaloids would require consuming an extremely large quantity of unripe green tomatoes, which is unlikely due to their bitter taste. However, smaller amounts can cause temporary digestive issues in sensitive individuals.

If you eat a large amount of raw, unripe green tomatoes, you may experience gastrointestinal upset, including nausea, vomiting, or stomach cramps. The risk is generally low, but depends on the quantity and individual sensitivity.

Yes, green tomato salsa and chutney are generally safe because the cooking process involved in making them helps to neutralize some of the glycoalkaloids. Additionally, the tomatoes used are typically unripe but not severely underripe.

Tomatine poisoning from green tomatoes is rare, but symptoms include vomiting, abdominal pain, and diarrhea. In severe, extremely rare cases, neurological symptoms could occur, but typically, the bitter taste prevents people from consuming enough to cause this.