Androstenone

What it is, structurally

Androstenone is a 16-androstene steroid, related to testosterone and dihydrotestosterone in the metabolic family tree but with no hormonal activity of its own. The body produces it as a downstream byproduct of androgen metabolism, mostly in the testes and adrenal cortex, and it gets secreted in sweat, saliva, and urine. It concentrates in male axillary (armpit) secretions, with women producing smaller amounts at lower steady-state levels.

The molecule is also famously present in boar saliva — where it functions as a verified, biologically active sex pheromone in pigs. Sows in estrus respond to it with the mating stance, which is why pig farmers have used synthetic androstenone sprays for decades. The boar pheromone framing is what kicked off serious human pheromone research in the 1970s and 80s: if it worked that cleanly in one mammal, the thinking went, maybe a related compound did similar work in humans. The human story has turned out far messier than the pig one, but androstenone remains the single most-studied candidate molecule for a human male pheromone, alongside its cousin androstadienone .

How people perceive it

This is the weird part. Genetic variation in a single odorant receptor — OR7D4 — gives different people wildly different perceptions of the same molecule. Three rough buckets show up in the data:

• About 30% of people find it intensely unpleasant — described as urine, stale sweat, or something rotting.
• About 40% find it sweet, vanilla-like, or pleasant — more like a soft musk.
• About 30% can't smell it at all — functional anosmia for this one molecule.

Those proportions shift by ethnicity and region, and the Keller et al. 2007 paper in Nature mapped the variation back to specific OR7D4 alleles. It remains one of the cleanest gene-to-perception links in olfactory science: change two amino acids in one receptor and the same chemical reads as either floral or fecal. The practical consequence is that you cannot predict how any given person will react to your cologne, because their nose is literally wired differently than yours.

The behavioral effects research

Most of the human work falls into three buckets, and none of them are settled.

Dominance and social perception: a handful of studies (varied in design and sample size) suggest that women exposed to ambient androstenone rate male faces as marginally more dominant, more aggressive, or higher-status than controls do. Effect sizes are small and the methodology ranges from tight to questionable. The general pattern shows up across enough labs that something is probably there, but "slightly more dominant in a forced-choice rating task" is a long way from "approaches you at a bar."

Risk-taking and decision-making: some lab work has shown shifts in economic-game behavior — slightly more aggressive bids, slightly less cooperative play — under androstenone exposure. Replication has been patchy and the published null results tend not to get the same press as the positive ones. Treat this bucket as suggestive at best.

Mood and arousal: genuinely contested. Some studies report mood improvement in a subset of subjects, others find no effect, and a few find a negative effect — concentrated, predictably, in the 30% of people who find the smell unpleasant. This is the cleanest illustration of the OR7D4 problem: the same molecule cannot have the same mood effect on a person who finds it sweet and a person who finds it rotten.

The honest summary: there is a real lab signal for androstenone affecting perception and behavior, but the inter-subject variance is large enough that population-level claims are easy to make and hard to defend. Wyatt's 2015 review in Proc R Soc B is the best skeptical read on where the whole field actually stands.

Why pheromone colognes use it

Androstenone is the most-cited "male pheromone" candidate in the commercial space even though the underlying evidence is mixed. Three reasons. It is cheap to synthesize at scale, so it does not blow up a product margin. It has at least some peer-reviewed behavioral signal, which gives marketing copy something real to point at. And the story is clean: boar pheromone, found in male sweat, makes women rate men as more dominant. That fits on a bottle.

Most major pheromone-for-men products list androstenone in the formula, often as part of an undisclosed proprietary blend so the actual concentration stays hidden. Pure Instinct , Nexus, Pherazone , and RawChemistry all reportedly use it. If you scan a label and see "pheromone complex" or "proprietary pheromone blend," androstenone is almost certainly in there somewhere.

How much actually matters

Detection thresholds are very low — humans who can smell androstenone at all can pick it up at picogram-to-nanogram concentrations in air. That is a tiny amount of molecule. But the behavioral effects reported in lab studies tend to use exposures well above detection threshold, often delivered as a steady ambient concentration over the course of a task, which is a very different exposure profile than a dab of cologne wearing off across a night out.

Whether the dose in a commercial cologne actually reaches a behaviorally-active threshold on the person standing next to you is genuinely unclear. Brands do not publish their concentrations, third-party assays of pheromone colognes are rare, and the available numbers vary by an order of magnitude across products. You cannot verify the dose, which means you also cannot verify the claim. That is the honest answer.

If you're going to use it

Less is more, and the margin is narrow. Over-applying an androstenone-forward cologne lands you in the trap where about a third of the people you encounter that night smell sweaty urine instead of soft musk. One small dab on the wrist, or one short spray to the chest under a shirt — not a full perfume application, not a fragrance cloud you can walk through.

A lot of the "pheromone cologne didn't do anything for me" reports probably belong to people who applied too much and pushed the molecule into the unpleasant range for half the room. Start light, see what happens, scale down further before you scale up. Our top picks flag which products run hot on androstenone, and the broader question of whether any of this works is covered in do pheromone perfumes work .

Further reading

• Keller, A., Zhuang, H., Chi, Q., Vosshall, L. B., & Matsunami, H. (2007). Genetic variation in a human odorant receptor alters odour perception. Nature 449: 468-472.
• Saxton, T. K., Lyndon, A., Little, A. C., & Roberts, S. C. (2008). Evidence that androstadienone modulates women's attributions of men's attractiveness. Hormones and Behavior 54(5): 597-601. (Androstadienone, not androstenone — a related but distinct androgen included here for context on the broader literature.)
• Wyatt, T. D. (2015). The search for human pheromones: the lost decades and the necessity of returning to first principles. Proc R Soc B 282: 20142994.