Generally speaking, pineapple is a nutritious fruit that most people can consume in moderation without strong or noticeable side effects. That said, some people may experience burning of the mouth or tongue due to the presence of bromelain in the fruit, as well as its high acidity. While it's considered more unusual, some individuals may have an oral allergy to pineapple that results in itching and swelling of the lips and tongue. And in even rarer incidences, a person may experience allergic anaphylaxis due to a pineapple-specific allergy. For those with pineapple-specific anaphylaxis, strict avoidance of the fruit is necessary.