If you love hot sauce, you already know capsaicin.
You might not think about it every time hot sauce hits your eggs, tacos, or wings, but it’s the compound responsible for that unmistakable heat. It’s what makes a jalapeño lively, a habanero serious, and what has certain peppers make you question your decisions.
However, despite how intense it feels, nothing is actually burning.
Let’s break down what capsaicin really is, how it works in your body, and why peppers developed it in the first place.
What Is Capsaicin?
Capsaicin is a naturally occurring compound found in chili peppers from the Capsicum family. It belongs to a group of compounds called capsaicinoids, which determine how hot a pepper or hot sauce feels.
It’s concentrated primarily in the white inner membrane of the pepper — often called the placenta. The seeds themselves don’t produce heat, but they can carry capsaicin because they sit against that membrane.
One important detail: capsaicin has no real flavor of its own. It doesn’t taste fruity, smoky, or sweet. Those characteristics come from the pepper itself. Capsaicin’s job is sensation. It’s the intensity dial.
How Do You Pronounce Capsaicin?
It’s pronounced cap-SAY-uh-sin.
Not cap-sigh-sin.
Not cap-see-sin.
Not cap-say-shun.
Capsaicin. Cap. SAY. Uh. Sin. We've heard so many iterations, but, only one is the correct way.
Now you can say it confidently while explaining to your friends why their nose is running.
How Capsaicin Works in the Body
Capsaicin interacts with a receptor in your nervous system called TRPV1. This receptor normally activates when you encounter high heat or irritation.
Capsaicin activates it without changing the actual temperature.
When that receptor fires, your brain interprets the signal as heat. That’s why spicy food feels like it’s burning even though nothing is physically hot.
Your body reacts as if it needs to cool down. You might notice:
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Sweating
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Flushed skin
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Watery eyes
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Runny nose
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Increased heart rate
- And of course, that signature mouth burn that keeps you coming back for hot sauce!
These are cooling responses. Your brain thinks there’s heat to regulate, so it responds accordingly.
The sensation is real. The temperature isn’t.
Does Hot Sauce Actually Burn You?
Under normal consumption, no.
Capsaicin creates a neurological response, not tissue damage. It stimulates pain receptors, but it does not burn your mouth the way a flame would.
Extremely high concentrations can cause irritation or digestive discomfort, but that’s your body reacting to intensity, not actual heat damage.
It feels dramatic because your nervous system treats it seriously.
Why Water Doesn’t Help
When the heat hits, most people reach for water. It makes sense, but it doesn’t actually solve the problem. Capsaicin is fat-soluble, not water-soluble, so water won’t dissolve it. In many cases, it just spreads the compound around your mouth and keeps the burn going.
Dairy works better because it contains casein, a milk protein that binds to capsaicin and helps pull it away from your receptors. That’s why milk, yogurt, or sour cream tend to calm the heat more effectively. Acid or sugar can change how the burn feels, but they don’t neutralize capsaicin. And in the end, the only guaranteed cure is time... your body eventually clears it on its own.
Why Peppers Contain Capsaicin
Capsaicin evolved as a defense mechanism.
Mammals tend to chew and destroy seeds, which isn’t ideal for a plant trying to reproduce. Birds, on the other hand, swallow seeds whole and disperse them elsewhere.
Birds are largely insensitive to capsaicin because their TRPV1 receptors respond differently. Mammals feel the heat. Birds don’t.
The result is strategic. Mammals back off. Birds spread the seeds. The pepper survives.
Humans, of course, decided to cultivate it and build entire cuisines around it.
Here’s a clean, blog-ready section you can drop straight in:
Are Bell Peppers and Hot Peppers Related?
Yes. They’re from the same genus: Capsicum.
In fact, many of the peppers you see at the grocery store, from sweet bell peppers to jalapeños and cayennes, are the same species: Capsicum annuum. The difference it's chemistry.
Bell peppers have been bred to produce little to no capsaicin, which is why they register at 0 Scoville Heat Units. The gene responsible for capsaicin production is essentially inactive. Hot peppers, on the other hand, actively produce capsaicin in the white inner membrane of the fruit, creating the heat we associate with spicy food.
Other well-known hot peppers belong to different species within the same genus. Habaneros, for example, are Capsicum chinense. Tabasco peppers are Capsicum frutescens. Still part of the Capsicum family, just different branches on the tree.
Same genus. Same botanical roots. Very different personalities.
The heat of peppers and hot sauce is measured in Scoville Heat Units, or SHU.
The scale was created in 1912 by pharmacist Wilbur Scoville. His original method was surprisingly simple and very human.
Ground peppers were dissolved in alcohol to extract the capsaicin. That extract was then diluted in sugar water and given to a panel of tasters. The mixture was repeatedly diluted until the tasters could no longer detect heat.
The number of dilutions required determined the pepper’s Scoville rating. If it took 5,000 dilutions before the heat disappeared, the pepper was rated at 5,000 Scoville Heat Units.
Yes, it was literally based on how much sugar water it took to hide the burn.
How Scoville Is Measured Today
Modern testing doesn’t rely on human taste buds.
Today, labs use high-performance liquid chromatography (HPLC) to measure the exact concentration of capsaicinoids in a pepper or hot sauce. The chemical concentration is then converted into Scoville Heat Units using a standardized formula.
It’s far more precise and removes the subjectivity of human tasters having good or bad days.
What the Numbers Mean
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Bell peppers: 0 SHU (no capsaicin)
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Jalapeños: roughly 2,500–8,000 SHU
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Habaneros: often 100,000–350,000 SHU
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Superhot peppers: 1,000,000+ SHU
The higher the capsaicinoid concentration, the higher the SHU.
In simple terms, Scoville measures how much capsaicin is present. The more capsaicin, the more dilution required, the bigger the number.
Did you know: Using our new and improved search function, you can search for hot sauces based on the peppers they use! Try it here
Can You Build a Tolerance?
You don’t become immune, but you can become less sensitive.
Repeated exposure to capsaicin can desensitize TRPV1 receptors over time. That’s why seasoned hot sauce fans can handle heat levels that would overwhelm someone new to spicy food.
Interestingly, this same mechanism is used in certain topical capsaicin treatments designed to reduce nerve pain. Prolonged stimulation can temporarily reduce pain signaling.
Your nervous system adapts.
Capsaicin and Health
Capsaicin has been studied for potential effects on metabolism, circulation, and appetite regulation. It also triggers the release of endorphins, which helps explain the rush some people feel after eating very spicy food.
That post-heat buzz isn’t in your head. It’s chemistry.
As with anything, moderation matters. Within typical culinary use, capsaicin is widely consumed and considered safe across cultures around the world.
The Role of Capsaicin in Great Hot Sauce
Heat alone isn’t the goal.
In a well-crafted hot sauce, capsaicin enhances flavor rather than overpowering it. It adds intensity, contrast, and energy. The best sauces balance heat with acidity, sweetness, smoke, and depth.
Peppers bring complexity. Capsaicin brings impact.
When used intentionally, heat elevates food instead of dominating it.
Final Word
Capsaicin is the compound that gives peppers and hot sauce their edge. It activates your body’s heat response, creates the burn you feel, and turns simple food into something memorable.
The next time you feel that warmth build, you’ll know exactly what’s happening.
Same molecule. Different thresholds. Endless ways to use it.