For some people putting chillies in a meal can ruin it completely, while for others they're necessary for food to be as tasty as can be.
But there's also a third category of people who seek out the hottest chillies around - and eat them in competitions.
"It does become almost sort of addictive in a way," says Chilli Dave, of the Clifton Chilli Club.
But it can go wrong - as one man finds out after eating the world's hottest chilli, the Carolina reaper, and suffering from "thunderclap" headaches.
It's the first time the headaches, which are caused by a sudden tightening of the vessels that supply blood to the brain, have been linked with chillies.
Why do people take part in chilli-eating competitions?
"When you have a really cheeky one your endorphins kick off and you get a bit of an adrenaline rush," Chilli Dave says.
He started off just taking part in chilli-eating competitions, but after winning a few with his friends they were asked to host a competition.
"With the really, really hot chillies, you get this lovely tingling, burning sensation, but it's actually not damaging you at all, it's all a trick of the mind," he says.
What do chillies actually do to your body?
Birds, unlike mammals, can't taste capsaicin - the chemical in chillies that make them hot for humans.
It helps ensure that chilli seeds are spread effectively - because birds aren't afraid to eat the plant.
But despite humans being able to feel the burn from the chillies' capsaicin, nutritionist Will Hawkins from Push Doctor agrees with Dave that it's all an illusion.
"Capsaicin is the main bioactive plant compound in chilli peppers, which can aid in the body's pain relief.
"It binds with pain receptors - the nerve endings in our bodies that sense pain - and although it can create a burning sensation, does not cause any burn injuries."
Chillies can actually help the body in a number of ways, Will says.
It can promote weight loss, by speeding up the body's metabolism, and can also reduce high blood pressure.
So why do people go red, start sweating and even vomit from eating chilli?
The physical effects of eating peppers can be seen as reactions to what might be - from the body's perspective - real burns, Bruce Bryant, a biologist at the Monell Chemical Senses Center in Philadelphia told BBC Futures.
Chilli Dave had a stomach ulcer he didn't know about and says his love of spicy food made that a lot worse.
"I was hospitalised for seven days unfortunately," he says.
Are chilli-eating competitions getting more popular?
Karl Muzio, from the Fiery Foods UK Festival, says his company's Brighton event is proving so popular this year that they'll hold three competitions over three days.
"With the chilli-eating competition there is always more competitors - victims you may prefer - than there are seats," he says.
"Entrants have traditionally been men but we have seen more women taking part recently."
And the Clifton Chilli Club, which has almost 150,000 subscribers on its YouTube channel, says the largest crowd it has ever held a competition in front of is 20,000.
"The industry in the UK is catching up and there's plenty of chilli farms and chilli sauce producers in the UK now," Dave says.
They may be proving popular both in person and with videos online showing people's reactions to eating super spicy chillies, but there are still risks, which is why festivals take precautions.
"We always have medics on hand should we have a negative reaction," Karl says.
"So far the worst we have had is vomiting, increased heart rate and some cramping of the extremities.
"Back stage we have full cream milk, yoghurt and sugar for the contestants. These all help to counter the heat effect of the chilli."