Understanding Why Do I Feel Sick After Eating Rhubarb?

October 16, 2025 •

4 min read

Rhubarb stalks are commonly used in delicious pies and jams, but a lesser-known fact is that the leaves are highly poisonous due to high concentrations of oxalic acid. This toxicity is a key reason why do I feel sick after eating rhubarb, although other factors related to the stalk itself can also cause digestive discomfort.

Quick Summary

Sickness after consuming rhubarb stems can be caused by the presence of oxalates and natural laxatives, with severe symptoms indicating potential rhubarb leaf poisoning. Proper preparation and understanding individual sensitivities are crucial for safe enjoyment.

Key Points

Toxic Leaves: Rhubarb leaves are highly toxic due to concentrated oxalic acid and must never be consumed.
Stalks Contain Oxalates: The edible stalks contain lower, usually safe, levels of oxalic acid, which can be further reduced by peeling and cooking.
Natural Laxative Effect: Compounds called anthraquinone glycosides in the stalks can stimulate bowel movements and cause digestive upset for some people.
High Fiber Content: Rhubarb's high fiber content can cause gas, bloating, and cramps, especially when consumed in large quantities.
Individual Sensitivity: Some individuals, particularly those with kidney problems, may be more sensitive to the oxalates in rhubarb.
Proper Preparation is Key: Always discard the leaves and consider peeling and cooking the stalks to reduce oxalate content and minimize digestive issues.

The Toxic Truth: Rhubarb Leaves and Oxalic Acid

It's a foundational rule of thumb for anyone who grows or cooks with rhubarb: never, under any circumstances, eat the leaves. The large, green leaves of the rhubarb plant contain exceptionally high and potentially lethal levels of oxalic acid. When ingested, oxalic acid can bind with calcium in the body, creating insoluble calcium oxalate crystals. While this is a rare occurrence with the stems, consuming the leaves can lead to a cascade of serious health problems.

Mild symptoms of rhubarb leaf poisoning can include a burning sensation in the mouth and throat, nausea, abdominal pain, and vomiting, which may resolve within a few hours. However, severe cases can result in kidney stones, kidney failure, breathing difficulties, and seizures. If you suspect you or someone else has eaten rhubarb leaves, it is critical to seek immediate medical attention by contacting a poison control center.

The Digestive Duo: Fiber and Anthraquinones

Even when the leaves are properly discarded, the edible stalks of rhubarb can still cause an upset stomach for some individuals. The culprit is not poisoning but rather a combination of the stalks' high fiber content and natural laxative compounds called anthraquinone glycosides.

Rhubarb is a fantastic source of dietary fiber, which is beneficial for most people in moderation. However, a sudden or large intake of fiber can overwhelm the digestive system, leading to gas, bloating, and cramps, especially for those not accustomed to a high-fiber diet. The other key players, anthraquinone glycosides, are natural stimulant laxatives that accelerate bowel movements. In Traditional Chinese Medicine, rhubarb root has been used for millennia for its laxative properties. For some, this effect can be overly potent, causing abdominal discomfort, cramps, and diarrhea, even when consuming the standard cooked stalks.

Individual Sensitivities to Oxalates

Beyond the raw toxicity of the leaves and the laxative effects of the stalks, some people may have a higher sensitivity to oxalates, the same compounds found in lower levels in the stalks.

Pre-existing kidney conditions: Individuals with a history of kidney disease or kidney stones may be advised by their doctor to avoid high-oxalate foods like rhubarb. Excess oxalate in the body can lead to the formation of calcium oxalate crystals, contributing to kidney stone formation.
Genetic predisposition: Certain genetic conditions can increase a person's susceptibility to health problems from oxalates.
Gut bacteria imbalance: Some research suggests that a healthy balance of gut bacteria, including specific strains like Oxalobacter formigenes, can help break down and neutralize dietary oxalates. An imbalance could leave some individuals more vulnerable to oxalate-related issues.

How to Safely Prepare and Enjoy Rhubarb

To minimize your chances of feeling unwell, proper preparation is essential. Here are some key steps:

Remove the leaves completely: Before cooking or even bringing rhubarb stalks into the kitchen, cut and discard all leaves.
Harvest early: Rhubarb stalks harvested earlier in the season typically have a lower concentration of oxalic acid than those harvested later.
Peel the stalks: The skin contains a higher concentration of oxalates than the inner flesh. Peeling the outer, tougher, and stringier layers of older stalks can help reduce the oxalate content.
Cook thoroughly: Boiling and discarding the cooking water is an effective way to remove a significant portion of water-soluble oxalates.
Pair with calcium: Consuming rhubarb with calcium-rich foods like milk, yogurt, or cream can help bind with the oxalic acid and prevent its absorption by the body.
Introduce it slowly: If you are new to rhubarb or sensitive to high-fiber foods, start with small portions to gauge your body's reaction.

Comparison: Toxin vs. Digestion-Related Sickness


Feature	Rhubarb Leaf Poisoning (Toxin)	Digestive Discomfort (Stalks)
Cause	Ingestion of toxic oxalic acid in leaves.	High fiber and natural laxatives in stems.
Severity	Can be mild to severe, potentially lethal in large doses.	Typically mild and temporary, causing discomfort.
Symptoms	Burning mouth, nausea, vomiting, abdominal pain, breathing issues.	Bloating, gas, cramps, diarrhea.
Action	Seek immediate medical help.	Adjust portion size, proper preparation, monitor symptoms.
Prevention	Do not eat the leaves under any circumstances.	Peel stalks, cook thoroughly, pair with calcium, eat in moderation.

Conclusion

Feeling sick after eating rhubarb is not always a sign of poisoning. Most commonly, it's a mild digestive reaction to the fibrous nature of the stalks or the plant's natural laxative compounds. However, the serious and potentially life-threatening danger posed by the rhubarb leaves cannot be overstated due to their high oxalic acid content. By understanding these key distinctions—the inherent toxicity of the leaves versus the digestive effects of the stems—you can safely enjoy this tart springtime vegetable. Always discard the leaves, prepare the stalks with care, and pay attention to your body's individual response to ensure a pleasant culinary experience.

If you are concerned about your body's reaction to oxalates or have pre-existing kidney issues, you can consult with a healthcare professional or registered dietitian for personalized advice.

Frequently Asked Questions

No, rhubarb leaves are highly poisonous to both humans and animals because they contain a toxic level of oxalic acid.

Accidental ingestion may cause mild symptoms like stomach upset, but you should still contact a poison control center immediately for guidance.

The edible stalks can cause digestive discomfort, such as stomach pain and diarrhea, primarily due to their high fiber and natural laxative content, not poisoning.

Cooking rhubarb stalks significantly reduces their oxalate content, making them safer and less likely to cause digestive issues. This does not apply to the leaves, which remain toxic.

People with a history of kidney stones, kidney disease, or certain gastrointestinal conditions like IBS should consult a doctor before consuming rhubarb due to its oxalate and laxative effects.

To minimize upset, always remove the leaves, peel the tougher outer layer of older stalks, cook the rhubarb thoroughly, and pair it with calcium-rich foods like dairy.

Rhubarb poisoning results from eating the highly toxic leaves and can be severe. Digestive issues come from the stems' fiber and laxative effects and are typically milder and temporary.