Usually the only way that a person can get sick from eating avocado is if they are allergic to it. Although avocado allergies are not that common, some people are allergic to this particular food and should avoid it at all costs because of the reactions it can cause, including upset stomach, diarrhea, and vomiting.
Those who do not store their avocado properly and then eat it are also in danger of getting sick as the result of tiny bacteria that grow on it. In order to avoid this altogether you will want to make sure that you keep your avocados in the refrigerator or freezer if you are not going to be eating them right away. This way you will be able to avoid getting sick from the avocados that you bring home from the supermarket.