Eating honey that has gone bad will most likely cause mild digestive upset, including nausea, stomach cramps, or diarrhea, that resolves on its own within a day or two. Honey rarely spoils in the traditional sense because its low moisture and high sugar content make it hostile to most bacteria and molds. But there are a few specific scenarios where “bad” honey can cause real harm, from fermented honey to contaminated imports to the rare but serious risk of botulism in infants.
Why Honey Rarely Goes Bad
Honey is one of the most shelf-stable foods in existence. Its water activity sits at about 0.60 or lower, which means there’s so little available moisture that nearly all bacteria, molds, and yeasts can’t grow. Most mold species need a water activity of at least 0.70 to even germinate, and the fungi commonly found in honey samples (species of Aspergillus and Penicillium) cannot produce harmful toxins at the water activity levels found in properly stored honey. Even honey’s natural antimicrobial compounds hold up over time: research on Australian honey stored at cool temperatures in the dark found that most samples retained at least some antimicrobial activity after 15 to 17 years.
Heat, light, and air exposure gradually break down these protective compounds, but that degradation makes the honey less beneficial, not dangerous. Old honey that has lost its antimicrobial punch is still safe to eat. The real problems start when moisture gets involved.
What Fermented Honey Does to You
Honey ferments when its moisture content rises above roughly 20%. This can happen if the jar is left open in a humid environment, if the honey was harvested too early before bees capped the comb, or if water drips in. At that moisture level, osmophilic yeasts (yeasts that thrive in sugary environments) begin converting the glucose and fructose into alcohol and carbon dioxide. The alcohol then breaks down into acetic acid, which is essentially vinegar. This is why fermented honey smells sour or boozy and may have a layer of foam or visible bubbles on top.
Eating a small amount of fermented honey typically causes mild gastrointestinal symptoms: nausea, bloating, loose stools, or stomach discomfort. It’s similar to eating any mildly spoiled food. For most people, symptoms pass within 48 hours without treatment. The main thing your body needs is fluid replacement, since vomiting or diarrhea can lead to dehydration. Water, broth, or electrolyte drinks are usually enough.
How to Tell If Honey Has Spoiled
Crystallized honey is not spoiled. Crystallization is a natural process where glucose molecules form solid crystals, turning liquid honey thick or grainy. You can reliquefy it by placing the jar in warm water. However, if you notice any of the following, the honey has likely gone bad:
- Foam or bubbles on the surface, which signal active fermentation
- A sour, vinegary, or alcoholic smell instead of honey’s typical sweet aroma
- Unusual color changes or separated layers, especially darkening that wasn’t there before
- A bitter, sour, or “off” taste that doesn’t match what you’d expect from honey
- Cloudiness combined with excessive moisture, which can indicate the honey has absorbed water and begun to break down
If your honey just looks crystallized but smells and tastes normal, it’s fine.
The Infant Botulism Risk
This is the one scenario where “bad” honey can be genuinely dangerous, and it doesn’t even require the honey to be spoiled. Perfectly normal, fresh honey can contain dormant spores of Clostridium botulinum, the bacterium that causes botulism. Adults and older children have enough stomach acid and established gut bacteria to destroy these spores before they cause problems.
Infants under 12 months do not. Their gut environment is immature: lower stomach acid, limited bacterial competition, and a developing immune system. When a baby ingests these spores, the bacteria can colonize the large intestine, multiply, and produce a potent toxin that causes progressive muscle weakness. Early symptoms include constipation, poor feeding, lethargy, a weak cry, and drooling. These can progress to generalized weakness, diminished reflexes, and difficulty breathing. Because the early signs overlap with normal infant fussiness, they’re easy to miss.
This is why every major pediatric health organization advises against giving honey to children under one year old, in any form, including baked goods where the honey wasn’t heated enough to destroy spores. If a baby who has consumed honey develops constipation followed by unusual floppiness or feeding difficulty, that warrants emergency medical attention.
“Mad Honey” and Grayanotoxin Poisoning
There’s a lesser-known type of toxic honey produced when bees collect nectar from certain rhododendron species, particularly Rhododendron ponticum and Rhododendron luteum. This honey contains grayanotoxins, compounds that interfere with nerve and muscle function. It’s most commonly encountered in the eastern Black Sea region of Turkey, though it can occur anywhere rhododendrons grow densely enough to dominate the local nectar supply.
Symptoms appear quickly, usually within 20 minutes to 3 hours of eating the honey. They include a drop in blood pressure, abnormally slow heart rate, dizziness, nausea, vomiting, sweating, and in more severe cases, impaired consciousness or fainting. The good news is that the effects are temporary. Most people recover within one to two days without lasting damage. Historical accounts describe affected people feeling normal again by the third or fourth day. Still, the cardiac symptoms (particularly the slow heart rate and low blood pressure) can be severe enough to require monitoring in a hospital.
If you’ve purchased honey from a small producer in a region where rhododendrons are common and develop these symptoms shortly after eating it, that’s worth a trip to the emergency room.
Adulterated Honey and Long-Term Risks
Some commercially sold honey isn’t really honey at all, or it’s been diluted with cheap sweeteners like high-fructose corn syrup. This won’t make you acutely sick the way fermented honey might, but it carries a different kind of risk. High-fructose corn syrup is processed differently by the body than the natural sugars in honey. The fructose can’t be used directly for energy and instead gets stored in the liver as fat or glycogen. Over time, heavy consumption of adulterated honey has been linked to elevated blood sugar, increased blood lipids, abdominal weight gain, and added strain on the liver and kidneys.
A review published in the journal Foods found that the organs most commonly affected by honey adulterants are the liver, followed by the kidneys, heart, and brain. Animal studies on long-term high-fructose corn syrup consumption showed kidney filtration failure in rats. While occasional exposure isn’t cause for alarm, regularly consuming adulterated honey thinking it’s the real thing means you’re getting none of honey’s antimicrobial or nutritional benefits and all the downsides of processed sugar.
To reduce your risk, buy honey from local beekeepers or brands that undergo third-party purity testing. Real honey crystallizes over time. If a jar stays perfectly liquid on the shelf for years, that’s worth questioning.