A pheromone is a chemical released by one body that produces a measurable response in another body of the same species, often without conscious awareness on either side. The word covers both the strict scientific definition set in 1959, where a single compound triggers a single repeatable behavior, and the broader working definition most researchers use today, where chemical cues between bodies influence mood, hormones, attention, and social behavior in ways that are real but harder to pin down to one molecule.
Most of the confusion around the pheromone definition comes from people using the word with one of those meanings while the person they’re talking to is using the other.
The strict version of the pheromone definition is what animal pheromone research is built on, and what skeptics fall back on when they argue that human pheromones do not exist. The broader version is what most working olfaction researchers use today, and what the field has settled into as the underlying phenomenon has become harder to deny.
This page covers both pheromone definitions, where the word came from, what pheromones are actually made of, where they come from in the body, and how the term separates from the related terms (hormones, body odor, chemosignals) it gets confused with.
The Strict Scientific Definition (Karlson and Lüscher, 1959)
The word “pheromone” was coined in 1959 by two German biochemists, Peter Karlson and Martin Lüscher. They built it from the Greek roots pherein (to carry) and hormon (to excite or stimulate), borrowing the second half of the word from “hormone” because the parallel was deliberate. Hormones carry chemical messages inside an organism. Pheromones carry chemical messages between organisms.
Their pheromone definition, in the original paper, is precise: a pheromone is a substance secreted by one member of a species and received by another member of the same species, in which it triggers a specific reaction, either a behavioral response or a developmental process.
Three things in that definition do most of the work.
Same species. A pheromone has to act within a species, not across species. The chemicals that warn one animal about a predator from another species are not pheromones, even if they trigger a clean behavioral response. They are kairomones or allelochemicals, depending on who benefits.
Specific reaction. The receiving organism has to do something measurable. A clean shift in behavior or a clean shift in physiology. Vague mood effects do not satisfy the strict bar.
Released and received. The compound has to leave one body and reach another. Internal hormones, even ones with social effects, are not pheromones.
Animal research clears this bar regularly. Boar pheromones (specifically androstenone in saliva) lock receptive female pigs into a mating posture within seconds of exposure. Ant alarm pheromones empty a nest in moments. Moth sex attractants pull males across miles of open air to a single female.
Human research clears the bar with more difficulty, which is what most of the modern argument over the pheromone definition is about.
The Broader Working Definition Used Today
The strict 1959 pheromone definition was built around animal research, and most of the field’s growth in the decades since happened in the same direction. By the time human olfaction researchers started seriously investigating chemical cues between people in the 1970s and 1980s, it became obvious that the strict bar was a poor fit for how human chemistry actually behaves.
Humans do not produce single compounds that trigger single repeatable behaviors the way moths and pigs do. Human chemistry produces complex mixtures of compounds that influence mood, hormonal state, attention, attractiveness ratings, mate selection, cycle timing, and recognition between specific individuals, in ways that vary by recipient, by context, by hormonal state, and by a dozen other variables.
By the strict pheromone definition, none of that counts as pheromone activity. By any reasonable working definition of “chemical cues between members of a species that influence behavior or physiology,” all of it does.
The field has handled this in two ways.
The broader pheromone definition. Most working olfaction researchers now use the word in a softer sense, where the requirement is that the compound be released by one body, picked up by another body of the same species, and produce a measurable effect, even if the effect is subtler than the animal-research bar requires. This is the definition most relevant to anyone asking what pheromones actually do.
The “chemosignal” alternative. Some researchers prefer to drop the word “pheromone” for human compounds entirely and use “chemosignal” instead, which sidesteps the strict definitional argument by using a different word. The phenomenon being described is the same. The label is more cautious.
Both approaches end up at roughly the same place. The chemistry between human bodies carries information that other human bodies pick up on, often unconsciously, in ways that influence behavior and physiology in measurable ways. Whether that gets called pheromone activity, chemosignaling, or something else is a labeling decision more than a substantive one.
For the purposes of someone using the word “pheromone” in plain English, the broader definition is the one that matches normal usage, and it’s the one most working researchers operate inside as well.
Pheromones vs. Hormones vs. Body Odor vs. Chemosignals
Four related terms get used interchangeably in casual conversation and shouldn’t be. Each one means something specific, and most of the confusion in popular pheromone coverage comes from collapsing them into each other.
Hormones. Chemical messengers that travel inside a single body. Testosterone, estrogen, cortisol, oxytocin. They originate in glands, travel through the bloodstream, and act on receptors elsewhere in the same body. Hormones never leave the body to act on someone else. The word “pheromone” was built off “hormone” precisely because the discoverers wanted to flag the parallel function in a different context.
Pheromones. Chemical messengers that leave one body and act on another body of the same species. Same molecular logic as hormones, just operating between organisms instead of within one. Some of the same compounds that work as hormones inside the body (androstenone, androstadienone, copulins) also work as pheromone candidates when released externally, which is part of why the categories blur.
Body odor. The full chemical output of a body’s surface, which includes pheromones but also includes skin oils, sweat compounds, bacterial metabolites, food and drink residue, and a long list of other molecules that have nothing to do with chemical communication. Body odor is the full mixture. Pheromones are a small fraction of what’s in it. Most of what makes body odor smell the way it does is bacterial activity on sweat, not pheromone content.
Chemosignals. The umbrella term for any chemical cue between organisms, including pheromones, but also including cues that don’t quite meet the strict pheromone definition. The word is preferred by some researchers who find the “pheromone” label too loaded with strict-definition baggage to apply confidently to humans. In practice, “chemosignal” and “pheromone” cover overlapping territory, with “chemosignal” being the broader term.
Putting them in a sentence: a body produces hormones internally, releases some of those hormones (and other compounds) externally as pheromones, the full external output combined with bacterial activity becomes body odor, and the whole external chemistry between bodies is what falls under chemosignaling.
Most popular coverage of pheromones gets the boundaries between these wrong. Mixing them up is one of the more common reasons for the confusion that makes the existence question seem more contested than it actually is.
What Pheromones Are Made Of
Pheromones are small molecules. That’s the most useful starting point. The compounds doing the work are tiny enough to evaporate from the body’s surface, travel through air, and reach a receiver’s olfactory or chemosensory tissue intact.
The chemistry sorts into a few major families, each producing pheromones in different organisms.
Steroidal compounds. The most-studied human pheromone candidates fall here. Androstenone, androstadienone, androsterone, estratetraenol. All built around the steroid skeleton, which means they share structural lineage with sex hormones like testosterone and estrogen. This structural overlap is part of why human pheromone research has been so productive in the steroid family: the body already produces these molecules for hormonal purposes, and some of them end up released externally where they can act on others.
Fatty acids. Copulins, the fatty acid mixture produced in the female body during fertility windows, are the most-studied human example. Short-chain fatty acids show up across many species as pheromone candidates, partly because they evaporate readily and partly because they’re easy for the body to produce as metabolic byproducts.
Peptides and proteins. More common in animal research than human research. Mouse pheromones include several peptide pheromone candidates that influence territory, mating, and stress response. Human peptide pheromones are less well characterized, though some of the protein content of saliva and skin secretions is being investigated for chemosignaling roles.
Volatile organic compounds (VOCs). A broad category that includes anything light enough to evaporate at body temperature. Many candidate human chemosignals fall into this category alongside the steroidal compounds, contributing to the “smell” component of body odor while sometimes carrying chemosignaling information as well.
What unites these families is molecular size. Pheromones have to be small enough to volatilize from skin, sweat, or other secretions, travel through air, and reach a receiver. Larger molecules don’t make the journey. This is why pheromone candidates tend to cluster into a relatively narrow molecular weight range, even though they come from chemically diverse families.
Synthetic pheromone products work with this same logic. The compounds in commercial bottles are usually lab-synthesized versions of the same molecules the body produces naturally, suspended in a carrier (alcohol, oil, or silicone) that lets them release at controlled rates rather than all at once.
Where Pheromones Come From In The Body
Pheromones are not produced uniformly across the skin. Specific regions of the body produce specific compounds, and the geography matters for understanding how pheromone communication actually happens.
Apocrine glands. Concentrated in the armpits, around the nipples, and in the groin and pubic regions. Apocrine glands are the workhorses of human pheromone production. They become active at puberty (which is part of why pheromone activity ramps up in adolescence), produce a thicker secretion than ordinary sweat, and are the source of most of the steroidal pheromone candidates in humans. The strong association between armpit chemistry and attraction research is not a coincidence: it’s where the relevant compounds are being produced in volume.
Sebaceous glands. Distributed across most of the skin surface, with higher concentrations on the face, scalp, chest, and back. Sebaceous glands produce the oily secretion (sebum) that protects skin and hair. They contribute fatty acids and other compounds to the broader body odor mix, including some pheromone candidates.
Eccrine glands. The body’s main sweat glands, distributed across most of the skin surface. Eccrine sweat is mostly water and salt and contributes very little to pheromone communication directly. What it does contribute is moisture that bacterial activity can work on, generating the secondary compounds that round out body odor.
Vaginal secretions. The primary source of copulins. The fatty acid composition shifts across the menstrual cycle, with concentrations rising during fertile windows. This is one of the cleanest examples of cycle-linked pheromone production in the human literature.
Saliva and breath. Less studied than the gland sources, but real. Some of the compounds in human saliva mirror compounds found in pig saliva that act as known pheromones, which is part of why kissing and close-range conversation are sometimes proposed as routes of pheromone transfer.
Urine. Studied more in animals than in humans, but human urine carries some of the same steroidal compounds found in apocrine secretions. The role in human social communication is generally minor compared to skin-based release.
The geography matters for product design too. The sites where pheromones are naturally produced (neck, chest, wrists, behind the ears) are also the places where applied pheromone products are designed to be worn, with the goal of reinforcing rather than replacing the body’s natural broadcast.
The Bottom Line
The pheromone definition has two layers. The strict 1959 definition, set by Karlson and Lüscher, requires a compound released by one organism to trigger a specific repeatable response in another organism of the same species. That bar is well-cleared by animal pheromones and harder to clear with human compounds, which is the source of most of the ongoing technical debate in the field.
The broader working definition used today is closer to the plain-English meaning: chemical cues between bodies of the same species that influence behavior or physiology in measurable ways. Most working olfaction researchers operate inside this broader pheromone definition, and most evidence for human pheromones sits comfortably within it.
Pheromones are small molecules, mostly steroidal or fatty acid based, produced primarily by apocrine glands in the armpits, groin, and chest, and to lesser degrees by other glands and secretions across the body. They are distinct from hormones (which act inside one body), from body odor (which is the full chemical output including bacterial byproducts), and from chemosignals (which is the broader umbrella term).
If you’re using the word “pheromone” in plain English, you’re using the broader pheromone definition, and that definition has been answered: human pheromones are real, and the chemistry between human bodies carries information in ways that other human bodies respond to. The strict definitional argument is a different conversation, and most of the people having that conversation agree on the underlying phenomenon even when they disagree on the label.
Related Pages In This Pheromone Guide
Each page below picks up a single concept covered in the hub article and gives it a closer treatment.
The Hub
- What Are Pheromones? The Updated 2026 Guide – the full pillar article covering definitions, science, mechanism, types, compounds, and effects.
Going Deeper On Specific Topics
- The pheromone definition – the strict scientific definition, the etymology, and why the standard works for animals but is harder to apply to humans.
- Are pheromones real or fake? – the buyer’s-eye version of the existence debate, with the patterns to watch for.
- The vomeronasal organ – the anatomy, the animal-vs-human debate, and the alternative receptor pathways that complicate the strict skeptic position.
- How pheromones work – the mechanism in more detail. Receptors, signal transmission, conscious vs unconscious processing.
- The four types of pheromones – primer, releaser, signaler, modulator, and how each maps onto the human evidence.
- Do pheromones actually work? – the efficacy question, separated from the existence debate. Individual variability, dose effects, what to expect.
- Pheromones and attraction – the attraction picture in its own deeper treatment. What the chemistry does in real interactions, beyond the popular image.
- MHC and attraction – immune-driven mate preference and the strongest piece of human attraction research backed by repeated studies.
- Pheromone myths – the press-recycled myths catalogued, with origins and what the evidence actually shows.
- How to use pheromones – application, dose, placement, and how long the effects last. The practical questions product pages tend to skip.
Reference Resources
- The compound library – every major human pheromone compound on its own dedicated page, with effects, dosage observations, and a decade-plus of community notes on each.
- The glossary – community vocabulary at a glance: hits, self-effects, fallout, signature, ghosting, deer-in-the-headlights, and the rest.
Recommended Products
- Best pheromones for men – the current top picks for men.
- Best pheromones for women – the same logic, applied to female-targeted formulations.
About This Site
- About House Of Pheromones – the origin story and editorial mission of this site.
- Joe Masters – author bio, credentials, and full archive of writing across the site.
- Editorial policy and testing methodology – how products are reviewed, what the field-testing standard actually looks like, and why affiliate revenue does not influence editorial.
- The Dark Aura Blackbook – a free guide compiling a decade of attraction and life-mastery work into one short, focused manual.
→ More about House Of Pheromones
- How To Create “Instant Chemistry” With Women (Spark Romantic & Emotional Chemistry) - April 4, 2026
- Revenge of the Pickup Artist Nerds: How the “Dating Advice” Industry Makes Millions Off Clueless Men - March 12, 2026
- How to ACTUALLY Use Pheromones (Plus Serious Attraction/Dating Tips for Men) - March 11, 2026
