One major concern with eating half-boiled eggs is the risk of Salmonella infection, a type of bacteria that can cause food poisoning. If eggs are not pasteurized or cooked properly, the bacteria may survive—especially in the yolk—leading to symptoms such as fever, diarrhea, stomach cramps, nausea, and vomiting. This risk is higher for people with weakened immune systems, pregnant women, children, and older adults.