A 25-year-old man has been shaving for years without ever seeing a thick hair on his cheeks. His brother, on the other hand, sports a full beard since adolescence. The difference is not due to diet or a lack of masculinity. The absence of a beard in some men can be explained by specific biological mechanisms, often misunderstood, where genetics and hormones play very distinct roles.
Androgen receptors and hair follicles: the real mechanism behind the absence of a beard
It is often said that beardless men lack testosterone. This is a persistent but inaccurate idea. Testosterone circulates in the blood of the vast majority of adult men at comparable levels, whether they have beards or not.
The real mechanism involves dihydrotestosterone (DHT), a derivative of testosterone produced by an enzyme called 5-alpha-reductase. It is DHT that activates the facial hair follicles to trigger the growth of terminal hairs, the ones that form a visible beard.
Where it really happens: each facial hair follicle has androgen receptors. Their number and sensitivity vary from man to man. A man may have a perfectly normal level of DHT but have few or poorly responsive receptors on his cheeks and chin. The result: no beard, or a very sparse beard, despite a normal hormonal profile.
As explained by Maison de Mode, this uneven distribution of receptors on the facial skin also explains why some men have hair only on their chin or mustache, with completely hairless cheeks.
Genetics and beard: what really gets passed down from one generation to the next
The density of the beard is largely hereditary. Family patterns are regularly observed: a beardless father is more likely to have a son with low facial hair. The genes involved are not limited to a single chromosome.
The beard depends on several genes that interact with each other, rather than a single “beard gene.” These genes control both the density of hair follicles on the face, the sensitivity of androgen receptors, and the rate of the hair life cycle. The three phases of this cycle (anagen, catagen, telogen) determine the duration of growth, transition, and shedding of the hair.
Marked differences are also observed according to ethnic origins. Some populations naturally exhibit less developed facial hair, without any link to hormonal imbalance. It is simply a variation in the genetic expression of receptors on the facial skin.
Age, an underestimated factor
The beard does not reach its maximum density at 18 years old. In many men, facial hair follicles continue to gradually activate until their thirties, sometimes beyond. A beardless face at 20 does not predict facial hair at 30.
This maturation delay often surprises, but it is perfectly physiological. Androgen receptors may become more sensitive over time, which explains the late appearance of hair in previously hairless areas.
Minoxidil on the face: what clinical trials say about the beard
This is a topic rarely addressed rigorously. Minoxidil, known as a treatment for scalp alopecia, is the subject of randomized clinical trials for beards. A trial conducted in 2016 showed that the application of 3% topical minoxidil on the face significantly increased hair density and diameter compared to a placebo.
A more recent trial in 2026 confirmed similar results in trans men undergoing hormone therapy, with an increase in the number of hairs per square centimeter.
The takeaway: there is no official approval for the use of minoxidil on the beard. The formulations available in pharmacies are approved only for the scalp. The instructions explicitly state not to apply the product to other parts of the body. Therefore, use on the face remains off-label (outside of marketing authorization), with possible side effects on facial skin that differ from that of the scalp.
- Clinical trials show measurable effectiveness on beard hair density, but over treatment durations of several months
- Stopping treatment generally leads to a partial regression of results
- Reported side effects include dry skin, irritation, and, in rare cases, unwanted hair growth in adjacent areas
5-alpha-reductase inhibitors and beard: a paradoxical side effect
Men who take finasteride or dutasteride to treat baldness act directly on 5-alpha-reductase, the enzyme that converts testosterone to DHT. By reducing DHT levels to protect scalp hair, these treatments can also slow down beard growth.
This is a rarely mentioned effect when prescribing. A man who is already not very hairy who starts a hair loss treatment may notice an additional decrease in facial hair. Protecting one’s hair and promoting one’s beard involve opposing hormonal mechanisms.
This paradox illustrates the complexity of the androgen system: the same hormone (DHT) promotes facial hair growth and causes hair loss on the top of the head.
Alopecia areata: when the beard disappears in patches
Some men develop patches in an otherwise uniform beard. Alopecia areata, an autoimmune disease, can specifically target facial hair follicles. The immune system attacks the follicles, causing circular areas without hair. This phenomenon is distinct from genetic absence of a beard and requires a dermatological diagnosis.
Male facial hair remains a complex biological trait, determined long before birth by the combination of genes inherited from both parents. Neither castor oil nor dietary supplements have demonstrated effectiveness in controlled trials to induce hair growth where follicles are absent or inactive. Understanding the true mechanisms also helps avoid wasting time and money on promises without scientific foundation.
