fresh cut pineapple
Sean Cate
Sean Cate
January 27, 2024 ·  3 min read

There’s a scientific reason why fresh pineapple makes some people’s mouths bleed

In our culinary world, a peculiar love-hate relationship exists between people and a particular golden, juicy tropical fruit. For some, its sweet and tart flavors evoke delight; for others, eating it becomes a source of discomfort or even pain. We are, of course, talking about pineapples. This article sheds light on the phenomenon where certain people experience pain after consuming this fruit. This less enjoyable encounter stems from a potent compound within the fruit— a protein-digesting enzyme called bromelain.1

The Inner Workings of Bromelain

Our tropical subject is rich in bromelain, a group of enzymes with a unique and powerful function. Beyond its culinary uses, which include tenderizing meat, bromelain has also found its place in the medicinal world. It’s traditionally been employed in treating inflammation and swelling, particularly post-operative.2 However, when bromelain interacts with human tissues, its potency can lead to some harsh effects, especially on the oral cavity.

This is because, amongst its many functions, bromelain breaks down proteins. Our mouth is a relatively vulnerable area, definitely not as tough as our outer skin – so when something squishy and vulnerable meets with something designed to break down proteins, it can get a little tingly for us.  When you eat pineapple, the bromelain interacts with the proteins in your mouth.3

It essentially begins ‘digesting’ them, leading to the physical sensation often described as a slight tingling or itching in the mouth. However, for individuals particularly sensitive to this enzyme, the reaction can escalate to a severely sore mouth, even with some cases of bleeding. The degree of discomfort caused by bromelain varies significantly among individuals. It is influenced by factors such as the amount of fruit consumed, the concentration of bromelain in the fruit, and the individual’s sensitivity to the enzyme.

Some may feel the tingle after just a few bites, while others may need to consume the entire fruit before experiencing the sensation. Despite its unpleasant nature, these oral effects of bromelain are typically short-lived, thanks to our stomach acid, which nullifies the feelings from bromelain upon swallowing, rendering it incapable of further protein breakdown.

Read: 3 Fruit-Infused Water Recipes

Pineapple Precautions

As previously touched on, the discomfort caused by bromelain can escalate beyond a mere tingling sensation. This scenario is particularly true for those with pre-existing mouth conditions like canker sores, gum disease, or cuts in the mouth. These conditions can become aggravated due to bromelain’s activity, leading to pineapple consumption-induced bleeding when present. Sensitive mouths can be subject to bleeding mainly from the tongue, as it’s the protein interacting most with the bromelain and has a relatively thin membrane to pierce before drawing blood. 

As a result, individuals with these conditions should consume this fruit cautiously. Even for those in good health, moderation is key. If the sensation becomes too unpleasant or if there are signs of an adverse reaction— like substantial pain or bleeding— it’s advisable to refrain from the fruit altogether.

On a positive note, bromelain can interact with certain medications, enhancing their absorption rate. Particularly any over-the-counter medications that help with osteoarthritis, muscle soreness, and injury after exercise, but the research is conflicting and inconclusive thus far. However, there is preliminary research suggesting bromelain does help remove dead and damaged skin from burn victims. 

Putting the Grim Fact in Perspective

While Bromelain’s effects can be alarming, viewing them in the right context is essential. In regular consumption quantities, this tropical fruit is generally harmless. Moreover, its proteolytic nature may offer health benefits, such as aiding digestion.

The notion of your mouth bleeding from eating pineapple is grim, but it’s a rare occurrence, generally linked to specific conditions or overconsumption. The majority of individuals enjoy this fruit without any issues, savoring its delightful balance of sweetness and acidity while also reaping its rich supply of vitamin C and other beneficial nutrients.

Ultimately, it’s important to approach this fruit and its potent enzyme, bromelain, with understanding and awareness. Such knowledge can guide us in consuming pineapple responsibly (starting to almost sound like an illegal substance) without fear. Like many aspects of our dietary habits, moderation is the key to enjoying this fruit and minimizing any potential discomfort.

Keep Reading: Graviola, The Antioxidant Super Fruit You’ve Never Heard Of


  1. Bromelain.” NCCIH
  2. An Overview of the Use of Bromelain-Based Enzymatic Debridement (Nexobrid®) in Deep Partial and Full Thickness Burns: Appraising the Evidence.” Oxford Academic. Yew L Loo, MBChB, et al. March 22, 2018
  3. Why Does Pineapple Make Your Mouth Tickle?McGill. Haleh Cohn. May 26, 2023.