Internal medicine and rheumatology specialist Siobhan Deshauer, MD, looks at the science of capsaicin.

Following is a partial transcript of the video (note that errors are possible):

Deshauer: The internet loves a spicy food challenge. It's dramatic, it's entertaining, and in some cases, it can be life-threatening. We're talking massive heart attack, brain spasm, torn esophagus, and even death.

This is a Carolina Reaper, one of the hottest peppers in the world, and I have been challenged to take a bite of it. If you've come to this video just to see me suffering, you can skip to the end. But is it just a mental challenge or could it actually be dangerous?

To find out what really happens when you take on the world's hottest peppers, I spoke with someone who has probably eaten more Carolina Reapers than anyone else in the world. This is Mike Jack. He holds 17 world records for eating hot peppers and we're going to watch him eat a shocking number of Reapers. But first, we're going to take a closer look to find out what makes this pepper so spicy.

See this white part? This is called the pith. It's the hottest part of the pepper because it has the highest concentration of a chemical called capsaicin. The more capsaicin, the spicier the pepper, and we can rate the spice level on the Scoville scale. Jalapeno peppers score around 2,500 to 8,000 Scoville heat units and this Carolina Reaper is 100 times spicier. Clearly, bigger doesn't mean hotter.

OK. Let's get back to Mike as he basically pepper sprays his mouth eating 164 Carolina Reapers in a row and I'll tell you what's happening inside his body at that time. As soon as Mike puts that pepper in his mouth, he is going to feel a burning pain like his mouth is literally on fire. That's by design. You see, most animals don't like the feeling of fire in their mouth, and in an attempt to prevent animals from eating them, peppers developed this self-defense chemical, capsaicin, which tricks your brain into thinking your mouth is on fire.

Capsaicin from the pepper activates a specific receptor in your mouth called TRPV1. These are the same receptors that would signal danger if you started pouring boiling water into your mouth. When the receptor is activated, it sends a pain signal to your somatosensory cortex. But what I find even more interesting is that the heat signal also reaches your hypothalamus, which regulates your body temperature and tells your brain that you're overheating, which is why your skin gets flushed and you start sweating when you're eating spicy food. You're not actually hot, your brain just thinks you are. We can see this happening in real time; 33 minutes into the challenge you can see that Mike feels like he is overheating. You can see his wife is putting ice packs on him and then his shirt comes off. Later, they bring in fans to help too.

The signal from your mouth also goes to the limbic system, which processes information about rewards and threats. This triggers feelings of fear and anxiety. Ultimately, your adrenal glands end up pumping out pure adrenaline, putting your body into a state of fight-or-flight. To successfully complete a pepper challenge, you not only have to bear the searing pain, but also the feeling of panic that sets in. Mike, like most world-class competitors, has trained himself to stay calm when he feels this surge of adrenaline.

Mike Jack: I listen to like a Buddhist breathing meditation. It keeps me calm and keeps me in the moment, and just like I don't know... it helps me think about... it's kind of weird. It helps me think about my priorities.

Deshauer: So far this all sounds extremely unpleasant, but it's actually not all bad. At a certain point, your brain will actually respond to the pain by releasing endorphins, which are a natural painkiller. It's just like the runner's high that marathoners describe. At this point in the competition, I sure hope Mike's brain is flooded with endorphins. After eating 164 Carolina Reapers at a steady pace for over 2 hours, he is finally done. Although he may not look it, he has got to be feeling pretty good right now, knowing that he has beat the world record. On the other hand, what comes in must go out. And we have the same pain receptors all the way through our gut and out the other end, so the pain doesn't end there.

Let's get back to our original question. Is this just mind over matter or can it actually be dangerous for your health? The short answer is yes, it can be, but rarely. Even though capsaicin isn't causing any direct damage, your physiologic response to the pain can be so intense that it can have life-threatening consequences. That's exactly what happened in these real, published medical case reports that we're going to talk about next.

This first case is a 47-year-old man who ate a ghost pepper in a food contest. He vomited so much that he sustained a full-thickness rupture of his esophagus called Boerhaave syndrome. The tear itself will cause pain and bleeding, but it gets worse. Undigested food, stomach acid, and digestive enzymes leak out into your chest, coming into contact with important structures like your heart and big blood vessels like your aorta. This can lead to horrible infections and chemical burns. If that wasn't bad enough, air can also leak in and that can compress the lungs making it difficult to breathe. If I'm worried about this, one clinical sign I look for is subcutaneous emphysema, which is when air travels under the skin. When you push on the skin, it actually feels like Rice Krispies crackling underneath.

But sometimes the damage isn't limited to your digestive tract, it can also directly affect your brain. This 34-year-old man participated in a hot pepper contest and he ate just one Carolina Reaper. Shortly after, he developed an excruciating headache that sent him to the emergency department.

The CT of his head was shocking. This scan shows a narrowing of multiple blood vessels in his brain. These blood vessels were spasming and contracting, limiting blood flow to certain parts of the brain and causing severe pain. This was caused by excessive adrenaline, the fight-or-flight hormone. One of the ways that it works is that it causes blood vessels to constrict, which is actually why your hands get so cold whenever you get nervous.

Watch the video above for more.