Ingredient explainer

Androstadienone

Also known as: AND; 4,16-androstadien-3-one; androsta-4,16-dien-3-one

Evidence: Mixed

A steroid derivative of testosterone found in male sweat and semen — the molecule with the strongest research signal for affecting women's mood and attention, though the strength of the effect remains debated.

What it is, structurally

Androstadienone (AND, the chemistry shorthand) is a 19-carbon steroid — a desaturated derivative of testosterone with two double bonds added at the 4 and 16 positions of the steroid backbone. It sits one or two enzymatic steps off the main androgen-metabolism map and carries no measurable hormonal activity of its own. The body produces it as a downstream metabolite of testosterone, mostly in the testes, and secretes it through apocrine sweat glands. It concentrates in male axillary (armpit) secretions and shows up in semen at meaningful levels. Women produce it too, in smaller amounts, with the steady-state ratio running roughly five-to-one male over female.

On the nose, AND is less polarizing than its better-known cousin androstenone . Most people detect it as a faint musky, slightly urinous note — closer to a soft skin musk than to anything aggressive. There is some individual variation in perception, but nothing like the three-way split (sweet vs rotten vs anosmic) that OR7D4 produces for androstenone. That makes AND easier to formulate around: a perfumer can include it without the bottle smelling completely different to the 30% of customers wired to find androstenone offensive.

Why it's the most-studied human candidate

AND has produced the cleanest behavioral signal in human pheromone research — which is to say, the cleanest signal in a contested literature where most candidates have produced nothing reproducible at all. Three papers form the spine of the debate.

Wyart et al. 2007 (Journal of Neuroscience) is the molecular-mechanism anchor. The team showed that smelling AND modulated cortisol levels in women within fifteen minutes of exposure, and produced distinct fMRI activation patterns in regions tied to attention and emotional salience. Men showed neither effect. This is the paper most often cited as evidence that AND is doing something real at the brain-chemistry level, even if the downstream behavior is messier.

Saxton et al. 2008 (Hormones and Behavior) pushed the question into the real world. Women at a speed-dating event were exposed to AND or a clove-oil control between rounds. Across the AND condition, women rated their male partners as more attractive than under control. The effect was modest but statistically significant, and it remains the closest thing to a "works in the wild" data point the AND literature has.

Hare et al. 2017 (Royal Society Open Science) is the canonical counterweight. A larger, more tightly controlled replication tried to reproduce the Saxton-style effect on women's perception of men's attractiveness and could not find it. They also tested estratetraenol (the proposed female counterpart) and found nothing. This is the paper skeptics like Tristram Wyatt point to when they argue the AND case is overstated.

So the honest summary: a real lab and fMRI signal from Wyart, a real social-context signal from Saxton, and no signal in the most careful replication attempt to date. That is the actual state of the science, not the marketing copy state of the science.

The Wyart fMRI finding

The Wyart 2007 paper is worth pulling out on its own because it sidesteps the behavioral-replication problem in a useful way. Even if AND does not reliably swing whether a woman finds a man attractive in a noisy social setting, it does measurably change brain activity. The fMRI work showed AND-driven activation in the anterior hypothalamus and in cortical regions tied to attention and salience processing — a pattern that suggests the molecule is being detected and routed sub-consciously, not just smelled and ignored.

The cortisol shift in the same paper points the same direction: a few breaths of AND produced a hormonal response in women, not in men, on a timescale too short to be psychosomatic. So something is being processed. What that processing translates into in real life — a flicker of attention, a small mood lift, nothing noticeable at all — is genuinely the open question. Wyart proves the gate is open; she does not prove what walks through it.

How women's products use it

Here is where AND's branding gets confusing. The molecule is produced primarily by men, but it shows up in plenty of women's pheromone products — used as a self-effect or confidence agent for the wearer rather than as a signal aimed at an observer. The logic comes straight from Wyart: if AND lifts mood and sharpens attention in women, putting it in a women's product is supposed to do that for the woman wearing it. The copulin content in the same bottle is what's aimed at the male nose.

Men's products also include AND, but for a different reason: it's part of the "this is what male skin actually smells like" framing, layered alongside androstenone and androsterone in the standard male blend. So the same molecule does double duty depending on the bottle. The literature ambiguity is matched by the product ambiguity. The Athena Pheromones review covers the canonical women's formulation, and the Pherazone review covers a men's product where AND is part of the stack.

How much makes a difference

This is the part nobody in the industry wants to talk about. Wyart's fMRI work used relatively high concentrations of AND — around 250 μM dissolved in a pentanol carrier, delivered directly under the nose in a controlled setting. Commercial perfumes use far less, applied to the skin where the molecule has to evaporate, diffuse, and reach a nearby person at meaningful airborne concentration.

Whether commercial concentrations come anywhere close to the threshold Wyart tested is genuinely uncertain. Brands almost never disclose AND concentrations on the label, and there is no standardization across the category. We cannot tell you whether your $50 cologne is delivering one percent or one hundredth of one percent of what the published work used.

The honest verdict

Androstadienone has the best evidence base of any human pheromone candidate. That base is still contested, the field's leading skeptic still calls it overstated, and the most careful replication attempt came up empty. If you are going to bet on one molecule mattering, this is the molecule to bet on. The bet is small, and the size of the wager should match.

For the broader honest take on the category, see do pheromone perfumes work . For the picks that actually include AND at meaningful-ish levels, see best pheromone perfumes for women and best pheromone perfumes for men .