Store-bought mayonnaise is generally safe thanks to pasteurized eggs and added acids—but only if handled properly. Once opened, it can pick up bacteria, especially if left out for more than two hours. Keep it refrigerated below 40°F (4°C).
Homemade mayo is riskier since it often uses raw eggs and no preservatives. Refrigerate it immediately, use it within a few days, and always use clean utensils. If anything seems off, throw it away.
