What Is Unhealthy About Stevia? Understanding the Risks and Side Effects

October 6, 2025 •

5 min read

Over half of US consumers use low-calorie sweeteners, with stevia being a popular choice. However, the question of what is unhealthy about stevia often arises due to concerns over additives, side effects, and differing research findings.

Quick Summary

This article examines the potential health concerns surrounding stevia, exploring issues like additives in commercial products, mild digestive and allergic side effects, and inconclusive research on gut and metabolic impacts.

Key Points

Additives, Not Pure Stevia, Cause Many Issues: The primary health concerns often come from fillers like erythritol, dextrose, or maltodextrin found in many commercial stevia products, not the steviol glycoside extract itself.
Digestive Distress from Sugar Alcohols: Sugar alcohols like erythritol can cause bloating, gas, and diarrhea in sensitive individuals because they are poorly digested.
Potential for Allergic Reactions: People with sensitivities to ragweed and related plants in the Asteraceae family may experience allergic symptoms from stevia.
Medication Interactions are Possible: Stevia's effects on blood sugar and blood pressure can interfere with medications for diabetes, hypertension, and lithium treatment.
Mixed Research on Gut Microbiome and Metabolism: The long-term effects on gut bacteria are still under investigation, with some studies suggesting minimal impact and others pointing to potential imbalance.
Check the Label for Erythritol Concerns: A 2023 study linked erythritol to a higher risk of heart attack and stroke, making it critical to read the ingredient list for stevia blends.

Stevia, a non-nutritive sweetener derived from the leaves of the Stevia rebaudiana plant, has gained widespread popularity as a sugar alternative. While its zero-calorie profile and plant-based origin appeal to many, particularly those with diabetes or looking to reduce sugar intake, it is not without its potential downsides. The health implications of stevia often depend on the form of the product and an individual's specific health profile. The highly purified steviol glycoside extracts, which are FDA-approved, differ significantly from the less-regulated whole-leaf or crude extracts. Understanding the specific risks is key to making an informed choice for your nutrition diet.

The Problem with Additives in Stevia Blends

A major source of concern regarding commercial stevia products stems not from the stevia extract itself, but from the additional ingredients used to bulk it up or balance its taste. Steviol glycosides are intensely sweet, so they are rarely sold in their pure form.

Sugar Alcohols and Digestive Distress

Many stevia products, such as packets or liquid blends, contain sugar alcohols like erythritol. While low in calories, sugar alcohols are not easily digested by the body and can cause significant gastrointestinal issues in sensitive individuals.

Bloating and gas: Undigested sugar alcohols ferment in the large intestine, producing gas that can lead to uncomfortable bloating.
Diarrhea: The presence of undigested sugar alcohols in the gut can draw water into the colon, leading to a laxative effect.

Dextrose and Maltodextrin

Fillers like dextrose and maltodextrin are also commonly found in powdered stevia blends. These ingredients can pose a problem for individuals with diabetes, as they have a high glycemic index and can cause a spike in blood sugar levels, contrary to the typical benefit of stevia.

Heart Health Concerns Linked to Erythritol

A 2023 study published in Nature Medicine raised significant concerns about erythritol, a common additive in stevia blends. The research suggested a potential link between higher levels of erythritol and an increased risk of blood clots, stroke, and heart attack. This finding emphasizes the importance of reading product labels and being aware of all ingredients, not just the primary sweetener.

Known Side Effects and Health Interactions

While highly purified stevia extract is generally well-tolerated, some individuals may experience mild side effects even from pure forms.

Allergic Reactions

Stevia is part of the Asteraceae plant family, which also includes ragweed, daisies, and marigolds. People with an allergy or sensitivity to ragweed may theoretically experience an allergic reaction to stevia, though documented cases are rare.

Drug Interactions

For people with specific medical conditions, stevia can interfere with certain medications.

Diabetes medications: Stevia has been shown to have a blood sugar-lowering effect. When combined with insulin or other antidiabetic drugs, it could potentially cause blood sugar levels to drop too low (hypoglycemia).
Blood pressure medication: The blood pressure-lowering properties of stevia can amplify the effects of antihypertensive drugs.
Lithium: Stevia acts as a diuretic, and taking it while on lithium could interfere with the body's ability to excrete the drug, leading to potentially dangerous accumulation.

Taste Perception and Palate Adjustment

Some users report a mild, licorice-like or bitter aftertaste with stevia products, which can be a significant turn-off. Prolonged use of intense sweeteners can also affect taste perception, potentially making less sweet foods, like fruits and vegetables, less appealing over time.

The Ongoing Debate: Gut Health and Metabolism

Scientific research into the long-term metabolic and gut health effects of stevia is still evolving, and studies present conflicting results.

Mixed Gut Health Findings: The gut microbiota metabolizes steviol glycosides. Some studies, particularly those on animals, suggest potential disruption to the microbial balance. However, newer human studies have shown no significant changes in overall gut bacteria composition after regular stevia consumption over a short period. The specific effect may be highly dependent on the individual's existing microbial makeup.
Weight Management Paradox: While a zero-calorie sweetener seems ideal for weight loss, the effect is not always straightforward. Some research suggests that replacing sugar with stevia can aid in weight maintenance. However, psychological factors, like the "health halo effect," where individuals feel justified in consuming more calories from other sources, can undermine weight loss efforts. Non-nutritive sweeteners may also increase appetite in some individuals.

Is Stevia Really Unhealthy? A Comparative Look

Conclusion: Making a Smart Choice

Ultimately, the question of what is unhealthy about stevia has a nuanced answer that depends on the specific product and consumer. Pure, high-purity stevia extract, when used in moderation, poses minimal risk for most people and offers a genuine zero-calorie alternative to sugar. The most notable concerns arise from the additives in many commercial blends, which can cause digestive issues, blood sugar spikes, and potentially more serious health risks depending on the filler. Individuals with pre-existing conditions like diabetes or high blood pressure, or those taking specific medications, should consult a healthcare professional before incorporating stevia into their routine due to potential interactions. Furthermore, the ongoing debate regarding stevia's impact on the gut microbiome and long-term metabolic health highlights the need for continued research. For health-conscious consumers, reading ingredient lists carefully is the best strategy to avoid unwanted side effects from fillers, while moderation is key to managing potential taste and metabolic impacts.

World Health Organization (WHO) Guidance on Non-Sugar Sweeteners

Frequently Asked Questions

Yes, but this is typically caused by the sugar alcohols, such as erythritol, that are often blended with stevia extract, rather than the stevia itself. These ingredients can ferment in the gut, leading to gastrointestinal discomfort.

Pure stevia extract does not affect blood sugar. However, some commercial stevia blends contain high glycemic fillers like dextrose or maltodextrin, which can raise blood sugar levels, especially in people with diabetes.

No. The FDA has only approved high-purity steviol glycoside extracts as generally safe (GRAS). Whole-leaf stevia and crude extracts are not approved for consumption due to a lack of safety information concerning potential effects on the kidneys, reproductive system, and cardiovascular system.

Yes. Stevia can potentially interact with medications for diabetes and high blood pressure, and it may interfere with the body's excretion of lithium.

The research on stevia's effect on gut microbiota is mixed and inconclusive. While some animal studies suggest potential disruption, more recent human studies have found no significant impact on overall gut bacteria composition, though certain functional changes were noted.

The relationship between stevia and weight is complex. While it is zero-calorie and can help reduce caloric intake when replacing sugar, some researchers suggest it could increase appetite or trigger a 'health halo effect,' potentially leading to weight gain.

Individuals taking medications for diabetes, high blood pressure, or lithium should consult a doctor. People with ragweed allergies might be sensitive. The whole-leaf form is not recommended for anyone, and pregnant women should be cautious, particularly with blends containing additives.