Sucralose and Saccharin: FDA Status, Studies and Side Effects

Sucralose is a no-calorie sweetener made from sugar by swapping three parts of the sucrose molecule for chlorine atoms, which makes it about 600 times sweeter than table sugar and keeps the body from using it for energy. It is widely sold in the US under the Splenda brand and appears in diet sodas, protein powders, flavored waters and many sugar-free gummies and drink mixes. The FDA approved sucralose for 15 food categories in 1998 and as a general-purpose sweetener in 1999. Since then, newer research has raised questions, including a 2023 WHO guideline and a lab study on a related compound. This guide covers what sucralose is, what regulators say, what the studies show, and the history of saccharin, the oldest sweetener in the pink packet.

Peptide Labs does not sell sucralose, saccharin or any sweetener as a product; sweeteners can appear among the inactive ingredients of some supplements. This article is general information, not medical advice.

What is sucralose?

Sucralose starts as ordinary sucrose. A multistep chemical process replaces three hydroxyl groups with chlorine atoms. The result still binds to the tongue’s sweet receptors, very strongly, but digestive enzymes do not break it down for energy, so it provides essentially no calories. Because so little is needed, tabletop packets usually add a bulking ingredient such as dextrose or maltodextrin so the packet pours like sugar; check the ingredient list if that matters to you.

Sucralose FDA status and acceptable daily intake

In the US, sucralose is an approved food additive. The FDA says it reviewed more than 110 studies designed to identify possible toxic effects before approval, and it lists an ADI of 5 milligrams per kilogram of body weight per day. An ADI is the amount regulators consider safe to consume every day over a lifetime, with a large safety margin built in. It is a regulatory benchmark, not a recommended amount.

Is sucralose bad for you? What the research shows

WHO's 2023 guideline on non-sugar sweeteners

On May 15, 2023, the World Health Organization advised against using non-sugar sweeteners to control body weight or reduce the risk of noncommunicable diseases. The list includes sucralose, saccharin, aspartame, acesulfame K, advantame, cyclamates, neotame, stevia and stevia derivatives. WHO based the advice on a systematic review that found no long-term benefit for body fat, along with observational associations between long-term use and type 2 diabetes, cardiovascular disease and mortality in adults. Observational links cannot show that a sweetener caused those outcomes, and WHO rated the guideline a conditional recommendation, meaning countries may weigh it differently. It does not apply to people with pre-existing diabetes, to toothpaste, skin products or medicines, or to low-calorie sugars and polyols, which WHO does not classify as non-sugar sweeteners.

The sucralose-6-acetate lab study

In 2023, Schiffman and colleagues published lab screening tests in the Journal of Toxicology and Environmental Health, Part B. They studied sucralose-6-acetate, an intermediate and impurity of sucralose manufacturing; commercial sucralose samples contained up to 0.67 percent of it. In genetic toxicity assays, sucralose-6-acetate broke DNA strands in cells, and gut tissue exposed to it in the lab showed more activity in genes linked to oxidative stress and inflammation. The authors argued that the amount in one sweetened drink could exceed a regulatory screening threshold for genotoxic substances. These were cell and tissue experiments, not studies of people, and they do not show harm at real-world intakes; they are a reason for further testing. FDA’s sweetener page still lists sucralose as approved with the same ADI.

Gut bacteria and blood sugar

A 2022 study by Suez and colleagues in Cell enrolled 120 adults who normally avoid sweeteners and gave them aspartame, saccharin, stevia or sucralose, below FDA’s ADIs, or a control for two weeks. Saccharin and sucralose significantly changed glucose tolerance on average, and the shifts tracked with changes in each person’s gut bacteria. Responses varied widely between individuals, and the study was short and small. For more on the microbiome itself, see how to improve gut health.

Sucralose side effects and heating

People sometimes attribute headaches or stomach upset to sweeteners, but evidence linking sucralose to specific symptoms is limited. Heating is a separate question. In 2019 Germany’s Federal Institute for Risk Assessment (BfR) reviewed data showing that sucralose gradually breaks down above 120 C and may form chlorinated compounds, possibly including dioxins and chloropropanols. BfR said the data were too thin for a final risk assessment and, until then, advised against heating sucralose-containing foods to baking, frying or roasting temperatures, or adding sucralose after cooking.

Saccharin: from warning label to approved sweetener

Saccharin, sold in the US as Sweet’N Low, Sweet Twin and Necta Sweet, is the oldest of these sweeteners and is 200 to 700 times sweeter than sugar. In the early 1970s, studies linked it to bladder cancer in rats, and Congress required a warning label on saccharin products. According to the FDA, more than 30 human studies later showed the rat results were not relevant to humans, and in 2000 the National Toxicology Program removed saccharin from its list of potential carcinogens; products no longer need the warning label. Its FDA ADI is 15 milligrams per kilogram of body weight per day. Saccharin was one of the two sweeteners that shifted glucose tolerance in the 2022 Cell study, and it is included in WHO’s 2023 guideline.

Sucralose vs other sweeteners

Each sweetener has its own evidence base, and we cover them separately: stevia, monk fruit, allulose, erythritol and other polyols. None of them is risk-free for everyone, and none is a proven weight-loss tool. If you are deciding between a sweetened product and a sugary one, comparing total added sugar is a reasonable starting point; our high fructose corn syrup guide explains how to read that line on the label.

• Sucralose: chlorinated sugar derivative, no calories, approved 1998 and 1999; heating and impurity questions.
• Saccharin: oldest option, warning label removed in 2000; bitter aftertaste for some people.
• Aspartame: carries a phenylalanine statement for people with PKU, per FDA.
• Plant-derived sweeteners: stevia and monk fruit extracts reach the market through GRAS notices.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a digestive or metabolic condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: High Fructose Corn Syrup: What It Is, HFCS vs Sugar and What Studies Show, Stevia Side Effects: Is Stevia Safe, and How Does It Compare to Sugar?, Sugar Alcohols: Xylitol, Diarrhea, Blood Sugar and Labels.