Eating a bad egg most often leads to a bout of food poisoning, with symptoms like diarrhea, stomach cramps, and nausea appearing within 8 to 72 hours. In many cases the illness is unpleasant but short-lived, resolving on its own within a few days. The severity depends on what kind of “bad” you’re dealing with: a spoiled egg that smells terrible or an egg contaminated with harmful bacteria.
Spoiled vs. Contaminated Eggs
A “bad egg” can mean two different things, and they carry different risks. A spoiled egg is one that has simply gone stale. As an egg ages, water inside the shell slowly evaporates and is replaced by gas. The egg becomes lighter, develops an off smell, and the texture of the white and yolk breaks down. If you crack open a truly rotten egg, the sulfur smell is usually strong enough that you won’t want to eat it. Accidentally swallowing a small amount of a spoiled egg might cause mild nausea or an upset stomach, but it’s unlikely to make you seriously ill on its own.
A contaminated egg is the bigger concern. Salmonella bacteria, specifically a strain called Salmonella Enteritidis, can be deposited inside the edible contents of an egg before the shell even forms. The bacteria colonize the hen’s reproductive tissues and end up in the yolk or white during egg production. That means a contaminated egg can look, smell, and taste completely normal. You can’t detect it by cracking the egg open or sniffing it, which is why proper storage and cooking matter so much.
Symptoms and Timeline
If you eat an egg contaminated with Salmonella, symptoms typically develop within 8 to 72 hours, though the incubation period can stretch anywhere from 6 hours to 6 days. The most common symptoms include:
- Diarrhea (sometimes watery, sometimes containing blood)
- Stomach cramps
- Fever
- Nausea and vomiting
- Chills and headache
For most healthy adults, these symptoms last anywhere from a few days to about a week and resolve without medical treatment. The illness is miserable but self-limiting. You may feel wiped out for a day or two after the worst symptoms pass.
Young children, older adults, pregnant women, and anyone with a weakened immune system face a higher risk of severe illness. In these groups, the infection can spread beyond the gut and become dangerous.
How to Recover at Home
The biggest risk from a typical case of egg-related food poisoning is dehydration. Diarrhea and vomiting drain fluids and electrolytes fast, so replacing them is the priority. Water, diluted fruit juice, sports drinks, and broth all help. Eating saltine crackers can also replace some lost electrolytes. If you’re an older adult or have a weakened immune system, oral rehydration solutions like Pedialyte are a better choice because they contain a precise balance of glucose and electrolytes.
You don’t need to follow a restrictive diet while you recover. Once your appetite returns, you can generally go back to eating your normal foods, even if diarrhea hasn’t fully stopped. Over-the-counter anti-diarrheal medications can help manage symptoms in adults, but avoid them if you have a fever or notice blood in your stool, as these are signs of a more serious infection that needs medical attention. These medications also aren’t safe for young children without a doctor’s guidance.
When Symptoms Are Serious
Most cases of Salmonella poisoning don’t require a trip to the emergency room, but certain signs mean you should seek care. Blood in your stool, a high fever, signs of dehydration (dizziness, dark urine, very dry mouth), or symptoms that last more than a few days all warrant a call to your doctor. Severe dehydration can develop quickly in young children and older adults, so watch for reduced urination, lethargy, or sunken eyes in vulnerable individuals.
How to Tell if an Egg Is Bad
The float test is the most popular home method. Place the egg in a bowl of water. Fresh eggs sink and lie flat on the bottom. Older eggs tilt upward or stand on end. Eggs that float to the surface are stale. This happens because water inside the shell gradually evaporates and is replaced by gas as the egg ages, making it less dense than the surrounding water. A floating egg is old enough that you should throw it out.
The limitation of the float test is that it only detects staleness, not bacterial contamination. A fresh egg that sinks perfectly can still carry Salmonella. Your nose is another useful tool: crack the egg onto a plate before adding it to your pan. A bad egg produces an unmistakable sulfur smell. If the white is unusually runny, the yolk breaks immediately, or anything smells off, discard it.
Proper Storage and Cooking
Refrigerated eggs stay safe and fresh far longer than eggs left at room temperature. Store them at 40°F or below, keep them in their original carton (not the door shelf, where temperatures fluctuate), and use them within three weeks for best quality. Never leave cooked eggs or egg dishes out of the refrigerator for more than two hours, or more than one hour if the room is above 90°F.
Cooking is the most reliable way to eliminate Salmonella. The bacteria are killed when the egg is heated until both the white and yolk are firm. Runny yolks, sunny-side-up eggs, homemade mayonnaise, raw cookie dough, and hollandaise sauce all carry more risk because they involve undercooked or raw egg. If you’re in a higher-risk group, sticking to fully cooked eggs significantly reduces your chance of getting sick.