Can you die from laughter?

A side-splitting joke might spur, between tears and gasps for air, the age-old exclamation: "I'm dying of laughter!" Although the expression is an obvious exaggeration, is there any truth behind it? Can people actually die of laughter?

Although it's highly unlikely, it's technically possible — and there have been documented cases of laughter-related deaths in the past, doctors told Live Science.

There are a few ways laughter could trigger a negative effect on the body. One of the most vulnerable of these pathways is via the heart. In rare cases, an especially hearty chuckle can cause something called "laughter-induced syncope," a condition that causes a person's blood pressure to drop rapidly during an exaggerated laugh. This triggers a heightened response from the autonomic nervous system — the network of nerves that regulates involuntary physiological processes — leading to a temporary dip in the amount of blood that flows to the brain, which can result in a loss of consciousness.

"When you laugh, you're moving your chest up and down, and it changes the pressure in the thoracic cavity [chest] and it can affect what's called the vagus nerve," which carries signals between the brain and most of the internal organs, Dr. Todd Cohen, chief of cardiology and director of medical device innovation at the New York Institute of Technology, told Live Science. "It can cause you to become lightheaded, [or] even — very, very, very rarely — pass out, especially when it's very exaggerated."

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The first documented case of laughter-induced syncope was in 1997, when a 62-year-old patient with hypertension and other heart-related issues fainted multiple times while roaring with laughter at the television show "Seinfeld," leading to the condition's nickname "the Seinfeld syncope."

The patient did not die from the condition, and this type of syncope usually just causes a person to pass out for less than a few minutes before coming to, Cohen said. Although it is technically possible for laughter-induced syncope to cause the heart to stop, the bigger risk from these fainting spells is that they could happen in dangerous situations, he added.

"It is possible that somebody can have this condition [and] fall and hit their head, or fall down a flight of stairs, or fall off the subway terminal into a train and die," he said, stressing that it's incredibly unlikely.

In other cases, laughter can affect the amount of air that gets to the heart, lungs and brain. For example, high emotions, such as deep amusement, can increase breathing rates and trigger flares of asthma symptoms, which can be further exacerbated by the unusual breathing associated with laughter. In a 2009 study, researchers surveyed 105 patients with asthma and found that more than 40% experienced laughter-induced asthma. In severe cases, asthma attacks can be fatal if someone does not have access to their inhaler.

In theory, laughter could also trigger a sudden spasm of the vocal cords — a condition known as a laryngospasm — or asphyxiation if a person does not get enough oxygen between laughs. But chances of these causes of death are slim, according to Dr. Megan Kamath, a cardiologist at UCLA Health and an assistant clinical professor of medicine at the David Geffen School of Medicine at UCLA.

"While there have been reported cases of death from laughter due to asphyxiation or cardiac arrest, it remains an overall unlikely cause of death for healthy individuals," she told Live Science in an email.

In fact, laughter is harmless — or even beneficial — to your health in the vast majority of situations, Cohen said.

"I think laughter and humor can help [patients] going forward with their condition and put a different perspective on their medical problem and keep them more present in the moments and enjoying life," he said.

Studies show that laughter can reduce anxiety by significantly lowering a person's levels of the stress hormone cortisol while increasing the release of dopamine, the brain's "feel-good" chemical. Additionally, laughing could help increase oxygen flow throughout the body and reduce inflammation in patients with coronary artery disease, according to a not-yet-peer-reviewed study presented at the European Society of Cardiology in Amsterdam in August.

"I believe laughter is the best medicine, and it's very unlikely to kill someone — but it's theoretically possible," Cohen said.