Stevia Side Effects: Is Stevia Safe? Blood Sugar, Weight and Fertility

Is stevia healthy? Does it cause weight gain? Can it affect fertility? These questions are being searched more and more. This guide answers each one clearly, based on what regulators and published studies say, and separates what is proven from what is a myth.

What Is Stevia Sweetener?

Stevia is a plant whose leaves contain sweet compounds called steviol glycosides, such as Reb A and Reb M. What is sold as stevia sweetener is not the leaf itself but a purified extract of these compounds, hundreds of times sweeter than sugar. Because so little is needed, it is usually blended with a bulking ingredient such as erythritol, so it is easy to use by the spoon or sachet. That is why you should always read the ingredients. Learn more in what is stevia Reb-M.

Is Stevia Safe? What Regulators Say

• The European Food Safety Authority (EFSA) reviewed the evidence in 2010 and concluded that purified steviol glycosides are not genotoxic or carcinogenic, setting an acceptable daily intake (ADI) of 4 mg/kg of body weight.^[1] Its 2024 review kept this ADI unchanged.^[2]
• In the United States, high-purity stevia extract (95% or more) is treated as safe for use in food, while whole stevia leaf and crude extracts are not approved as food additives because of insufficient safety data.^[3]

As a guide, this is the ADI by body weight, expressed as steviol equivalents:

Body weight	ADI (steviol equivalents)
50 kg	200 mg
70 kg	280 mg
90 kg	360 mg

The amount used to sweeten one cup is far below this limit for most adults, because the extract is so sweet.

Possible Stevia Side Effects

1. Bloating or stomach upset

This is the most common complaint, and the cause is usually not stevia itself but sugar alcohols blended with it, such as erythritol or maltitol. Erythritol is better tolerated than most, but large amounts can cause diarrhoea, which is why EFSA set an ADI for it of 0.5 g per kg of body weight.^[6]

2. A bitter or metallic aftertaste

Some older types of stevia, such as Reb A, can leave a bitter finish. Newer types such as Reb M taste closer to sugar. This is not a health issue, but it is a common reason people dislike stevia.

3. Allergy

Stevia belongs to the daisy family, like chamomile and ragweed. Allergy to the purified extract is rare, but people with a known allergy to this plant family should ask their doctor.

4. The erythritol and heart question

In 2023, an observational study found that higher blood levels of erythritol were linked to a higher risk of heart attack and stroke in people who already had cardiovascular risk factors.^[7] The study shows an association, not proof of cause; the body also makes erythritol itself, and research is ongoing. If you have heart disease, ask your doctor which sweeteners suit you.

Does Stevia Raise Blood Sugar?

No. Steviol glycosides have almost no calories and are not digested like sugar. In a study in adults, a stevia-sweetened preload before a meal led to lower glucose and insulin levels after eating than a sugar-sweetened one.^[4] Still, check the rest of the label, because some blends contain sugar or dextrose. Read more in stevia for diabetics.

Does Stevia Cause Weight Gain?

Stevia itself has almost no calories, so it does not add weight directly. However, in 2023 the World Health Organization advised against relying on non-sugar sweeteners, including stevia, for weight control, because studies showed no long-term benefit for body fat. This is a conditional recommendation and does not apply to people with diabetes.^[5] In short, stevia helps you cut sugar in your cup, but it is not a weight-loss tool on its own; your overall diet matters most.

Does Stevia Cause Infertility?

There is no evidence of this in humans. The myth comes from old traditional uses of the leaves and from animal studies using crude extracts at doses far higher than people consume. When setting the ADI, regulators reviewed long-term animal studies and added a large safety margin above the highest dose that showed no harm.^[1]

Is Stevia Safe in Pregnancy and for Children?

Regulators consider intake within the ADI safe for the general population, but pregnant and breastfeeding women should always check dietary changes with their doctor. For children, some health groups advise caution because long-term data are limited and getting children used to sweet tastes is not a good idea.^[3] For young children, it is best to limit sweetened drinks in general.

How to Choose Stevia Safely

• Look for steviol glycosides, Reb A or Reb M on the label; this is the purified extract.
• Read the other ingredients: erythritol, maltitol, dextrose or sugar.
• If your stomach is sensitive, start with a small amount.
• Use it to cut sugar, not to eat more sweet foods.
• If you have a chronic condition or take medication for blood sugar or blood pressure, ask your doctor.

What Does Lucarise Use?

At Lucarise we use stevia Reb-M, one of the purest types of stevia and the closest to sugar in taste. Our tabletop sachets (Classic and Cardamom) combine Reb-M with erythritol, at 1 g per sachet. Many of our drinks come with a separate sweetener sachet, so you decide how sweet your cup is, or skip it.

This article is general information and does not replace advice from your doctor.

Quick questions

References

1. EFSA Panel on Food Additives (2010). Scientific Opinion on the safety of steviol glycosides for the proposed uses as a food additive. EFSA Journal 8(4):1537. doi.org
2. EFSA Panel on Food Additives and Flavourings (2024). Extension of use of steviol glycosides (E 960a–d) and modification of the ADI for steviol. EFSA Journal 22(11). doi.org
3. Center for Science in the Public Interest. Stevia / steviol glycosides: Chemical Cuisine rating (updated 2026). cspi.org
4. Anton SD, Martin CK, Han H, et al. (2010). Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels. Appetite 55(1):37–43. pmc.ncbi.nlm.nih.gov
5. World Health Organization (2023). WHO advises not to use non-sugar sweeteners for weight control in newly released guideline. www.who.int
6. EFSA Panel on Food Additives and Flavourings (2023). Re-evaluation of erythritol (E 968) as a food additive. EFSA Journal 21(12):8430. www.efsa.europa.eu
7. Witkowski M, Nemet I, Alamri H, et al. (2023). The artificial sweetener erythritol and cardiovascular event risk. Nature Medicine 29:710–718. doi.org

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