Short answer: Androstadienone, often called A1, is a steroid found in human body odor and studied as a possible chemical signal. Some experiments report changes in mood, attention, or attractiveness judgments under particular conditions; others find no effect on attractiveness. It has not been established that wearing an A1 fragrance creates attraction or deeper emotional connection in everyday life.
What it is: An odorous steroid sometimes studied under the name 4,16-androstadien-3-one.
What studies suggest: Some laboratory and speed-dating experiments found context-dependent mood or rating changes.
What remains unresolved: Other double-blind research found no effect on attractiveness ratings; a predictable human pheromone response has not been demonstrated.
Buying implication: A product containing A1 should be evaluated as a complete fragrance or formula, with attention to ingredient disclosure and price.
What is androstadienone?
Androstadienone (androsta-4,16-dien-3-one) is a steroid compound associated with human body odor, including male axillary secretions. Researchers have exposed volunteers to purified androstadienone to examine smell, mood, attention, physiology, and social judgments. In this literature it is commonly called a putative human pheromone: a proposed candidate whose role has not been conclusively identified. That distinction matters when marketers describe A1 as if a specific romantic effect were already proven.
What have controlled studies found?
A study of exposure below conscious detection reported mood effects in heterosexual women when the experimenter was male, but not when the experimenter was female; it did not find the same pattern for behavior. A separate speed-dating experiment found higher ratings of men’s attractiveness in two of three events among women exposed to androstadienone. These results are interesting and specific to those study settings.
A later double-blind experiment testing androstadienone and estratetraenol found no effect on attractiveness or unfaithfulness ratings of opposite-sex faces. Studies use different tasks, doses, controls, and social contexts, so a positive finding in one design is not a guarantee in another. A review of human pheromone research argues that robust identification of a human pheromone needs a stronger chain of evidence than studies of isolated candidate steroids have provided.
Does A1 improve mood or create a bond?
Some research reports changes in self-rated mood or attention after exposure, but the effects have depended on the experimental context. A laboratory result does not establish that a person wearing a retail cologne will feel better, that a partner will feel safer, or that a relationship will deepen. The old article presented “social buffering,” calmness, and a slow-building romantic effect as product-like benefits without evidence for those outcomes. Those assertions have been removed.
The same caution applies to sweeping warnings that “too much” A1 causes headaches, depressive feelings, or aggression. A fragrance can be unpleasant or irritating to an individual, but we did not find a reliable, product-independent dose threshold for the specific psychological effects claimed in the old copy. Follow a product’s directions, review the ingredient label, and stop using a fragrance that causes discomfort.
How to assess products that mention A1
| Question | What to look for |
|---|---|
| Is A1 actually disclosed? | Look for the compound name or androstadienone, not a vague “pheromone” claim alone. |
| How much is stated? | Separate milligrams per bottle from the amount of each compound in a multi-ingredient blend. A larger number does not prove better effects. |
| What else is in the product? | Carrier, fragrance, allergens, and other compounds affect the finished product and wear experience. |
| What was tested? | A study of purified A1 is not a controlled trial of the retail formula or an attraction guarantee. |
| What are the purchase terms? | Check size, total price, shipping, and whether an opened bottle can be returned. |
For examples of formulas that list A1 among other ingredients, see our IMPI Red review and Edge Sandalwood review. Their seller-stated ingredient amounts are useful product details, but they do not establish the social outcomes claimed for the blends. Our Nexus review applies the same buying questions to our leading men’s pick.
Frequently asked questions
Is androstadienone the same as androstenone?
No. They are different steroid molecules. Our androstenone guide covers that compound separately.
Is A1 a proven human pheromone?
It is a well-studied candidate, but the evidence does not establish a specific, reliable pheromone response in humans.
Do the positive speed-dating results prove colognes work?
No. The study tested controlled exposure to the compound and found a result in two of three events. It did not test a commercial cologne or guarantee real-world dating outcomes.
What dose should I use?
There is no validated universal dose for attraction. Follow the directions for the particular fragrance and avoid treating isolated research doses as consumer instructions.
Final verdict
Androstadienone is a legitimate subject of human odor research, with some context-dependent findings and some null results. It should not be sold to readers as a reliable mood enhancer or a tool for deeper connections. When shopping, assess the finished product’s fragrance, disclosures, price, and return terms. See our Nexus review for a product-level comparison.
Editorial note: Primary studies and review literature checked October 7, 2026. This is an evidence guide; we have not independently tested A1 or a finished product for attraction outcomes.
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