Commercially produced mayonnaise is an unlikely cause of food poisoning. This is because it is made with pasteurised eggs, which are heat treated to kill harmful bacteria, such as salmonella. It also has a high level of acidity from ingredients such as vinegar or lemon juice which inhibits bacteria growth. Homemade mayonnaise, on the other hand, is made with raw egg yolks, which may contain harmful bacteria, and should be avoided.

Keep in mind that any food has the potential to cause food-borne illness. For example, harmful bacteria can be introduced into a food during harvesting or manufacturing or from unwashed hands during preparation. If a food sits out and is allowed to get warm, it provides a perfect breeding ground for such bacteria.

To keep your mayonnaise-based salads safe, follow these tips:
* Wash all produce thoroughly with clean, cold water.
* Use commercially made mayonnaise instead of homemade mayonnaise.
* Refrigerate salads immediately after preparing them and keep them at 40 F until they are served to prevent the growth of bacteria.
* Don't leave cold food out at room temperature for more than two hours.
* When mayonnaise-based salads must sit out, put them in a shallow container surrounded by ice and replace the ice as needed.