WHAT THE SCIENCE SAYS

The heat is
in your nerves.

A chilli is not actually hot.

A scatter of fresh red and green chillies on a worn wooden chopping board in warm side light — AI-generated image, not a photograph of a real person or place.

Heat sits in the ribs
Scoville counts dilutions
Milk beats fizz
Spice, explained

Its capsaicin switches on a sensor in our nerve endings that normally fires at painfully high temperatures, so the brain reads it as burning. Knowing that explains where the heat sits and what calms it.

Updated 14 October 2026

THE SHORT ANSWER

Capsaicin flips
a heat switch.

Chilli burn is a sensation, not a flavour.
It comes from one compound and one sensor.

THE SENSOR

A heat detector, fooled

Research using capsaicin found TRPV1, a sensor in nerve endings that is activated at temperatures we feel as painful. The work won the 2021 Nobel Prize.

How it works

THE PEPPER

Blame the ribs, not the seeds

University of Arizona extension says the heat comes from capsaicin glands along the placenta, the pale ribs. Seeds just sit close by.

Handling tips

THE FIX

Reach for milk

In a Penn State study, whole and skim milk cut the burn most. Fizzy drinks did poorly, and alcohol makes it worse.

Compare drinks

A QUICK DRINK CHECK

What should you
drink for the burn?

Pick a drink to see how it did in Penn State's taste tests on capsaicin burn. The bar shows how much it helped.

Based on Penn State Sensory Evaluation Center studies published in 2019 and 2024.

Drink check

Choose a drinkWhole milkSkimmed milkA sweet fruit drinkPlain waterBeer or fizzy drinks

Whole milkAmong the best

Whole milk gave one of the largest reductions in burn among the drinks tested in the 2019 study.

Skimmed milkJust as good

Skim milk worked as well as whole milk, which suggests protein matters, not only fat. A 2024 follow-up found higher-protein milks did even better.

A sweet fruit drinkSurprisingly good

A sugary fruit drink was also among the best. Researchers think the sweetness overwhelms the burn rather than removing capsaicin.

Plain waterSome help

Every drink tested reduced the burn significantly, water included, but milk did better than water in both studies.

Beer or fizzy drinksPoor choice

Carbonated drinks performed poorly. The researchers add that real beer would be worse still, because alcohol amplifies the sensation.

Source: Penn State news releases on studies in Physiology and Behavior (2019, 72 participants) and Food Quality and Preference (2024).

TWO NUMBERS WORTH KNOWING

From sweet peppers
to pure fire.

How far the Scoville scale stretches,
and how many chilli species people grow.

16million SHU

Scoville heat units of pure capsaicin

University of Arizona extension says pure capsaicin measures 16,000,000 Scoville heat units. On the same scale, sweet peppers score 500 or less.

PURE CAPSAICIN · U. ARIZONA

5

Domesticated chilli pepper species

Capsicum annuum (bell, jalapeño, cayenne), frutescens, chinense (habanero, Scotch bonnet), pubescens and baccatum. Chillies were among the first crops domesticated in the Americas.

SPECIES · U. ARIZONA

The original Scoville test dilutes a chilli extract in sugar water until a panel of tasters can no longer detect heat. Modern labs measure capsaicinoids directly by liquid chromatography (HPLC).

A glass of milk beside a bowl of spicy red noodle soup on a wooden table — AI-generated image, not a photograph of a real person or place.

FOUR KITCHEN HABITS

Control the heat
before it bites.

Extension guidance from US universities covers handling and taming chillies. None of it needs special kit.

Cut out the ribs
The inner ribs hold the capsaicin glands. Removing them reduces a chilli's heat.
Wear gloves
Colorado State University extension advises gloves and glasses when handling chillies, to protect skin and eyes.
Oil, then soap
To remove capsaicin from skin, rub with vegetable or olive oil, wipe off, then wash well with soap and water.
Taste as you go
Heat varies by variety, and within one type it can vary, possibly by a factor of 10 or more, with seed, climate and soil.

THE NOBEL CONNECTION

How a chilli
found a sensor.

In the late 1990s, researchers searched millions of DNA fragments from pain-sensing nerve cells for the one that made cells respond to capsaicin. They found a single gene, for an ion channel now called TRPV1.

TRPV1 is activated by heat we perceive as painful, which is why capsaicin feels like burning. Related work used menthol to identify TRPM8, a sensor activated by cold. The 2021 Nobel Prize in Physiology or Medicine recognised these discoveries.

A red chilli sliced lengthwise, showing the pale inner ribs and the seeds attached to them — AI-generated image, not a photograph of a real person or place.

Questions

Questions people ask

Are chilli seeds the hottest part?

No. University of Arizona extension says the heat comes from capsaicin glands along the placenta, the inner ribs. Seeds are blamed because they are attached right next to it.

What is a Scoville heat unit?

Originally, a measure of how far a chilli extract must be diluted in sugar water before tasters stop detecting heat. Labs now measure capsaicinoid content directly and convert it to Scoville units.

Is full-fat milk better than skimmed for spicy food?

Not according to Penn State tests: skim milk cut the burn about as well as whole milk. A 2024 study found higher-protein milks, including high-protein soy milk, worked better.

Why does beer not help with spicy food?

Carbonated drinks did poorly in Penn State's tests, and the researchers say alcohol amplifies the burning sensation.

Does the same idea explain mint?

The 2021 Nobel Prize announcement describes how menthol was used to identify TRPM8, a receptor activated by cold, just as capsaicin led to the heat sensor TRPV1.

The heat is
in your nerves.