Hair Loss in Men and Women — Understanding the Science Behind Our Changing Hair
Part Five of the APPLE & BEARS Human Hair Series
Decades ago, a friend posed a simple question:
“We can travel to the Moon, so why can’t we cure baldness?”
Years later, while waiting at a supermarket checkout, I noticed that the woman serving me had a noticeably receding hairline. Around her, daily life carried on undisturbed. She may have been entirely at peace with her appearance; there was no way of knowing. Yet that brief encounter was a reminder of how widespread hair loss is, how differently it touches each individual, and how central it remains to our shared human experience.
Between clinics offering overseas surgical transplants and television advertisements marketing miracle shampoos, hair loss attracts considerable commercial attention. Yet it raises an essential scientific question: can everyday hair care truly alter the complex biological machinery of human hair loss?
1. Continuing Our Human Hair Series
In Part Four, The Silver Years: Why Human Hair Turns Grey or White, we explored why our hair gradually loses its natural colour as we age.
Now, in Part Five, we turn from changes in hair colour to changes in hair growth: why does hair become thinner, shed more noticeably or disappear from parts of the scalp?
Part Four also touched on alopecia areata when exploring apparently sudden whitening. Here, we look more closely at hair loss itself and why different causes require different approaches.
2. The Biology of the Follicle
Each hair follicle is a dynamic micro-organ embedded in the skin. At its base, the dermal papilla acts as a specialised signalling centre, communicating with surrounding cells through molecular pathways to help coordinate follicular growth and regeneration.
Follicles naturally cycle through phases of growth (anagen), regression (catagen), and rest (telogen).
The Human Hair Growth Cycle — Understanding the three natural phases of hair growth, transition and rest. Simplified scientific illustration.
In androgenetic alopecia, or pattern hair loss, affected follicles progressively miniaturise. In male pattern hair loss, genetically susceptible follicles respond to dihydrotestosterone (DHT), a potent androgen produced when the enzyme 5-alpha-reductase converts testosterone. Over successive cycles, affected follicles produce shorter, finer hairs, making the scalp increasingly visible.
Female pattern hair loss also involves follicular miniaturisation, although the hormonal contribution is more complex and should not be assumed to be identical in every person.
The follicle does not necessarily vanish when thinning first becomes visible. This helps explain why treatment can sometimes slow progression or improve visible growth, although results vary and complete restoration cannot be promised.
Hair Follicle Miniaturisation — How healthy hair follicles gradually produce thinner, shorter hairs in pattern hair loss. Simplified scientific illustration.
3. Why a Universal Cure Eludes Us
Hair loss is not a single condition, but an umbrella of distinct biological mechanisms:
- Androgenetic alopecia: Pattern hair loss involving inherited susceptibility and follicular miniaturisation, with hormonal influences that differ between individuals.
- Alopecia areata: An autoimmune condition in which the immune system attacks hair follicles.
- Telogen effluvium: Increased shedding following disruption of the normal hair cycle, sometimes after illness, physiological stress, childbirth or nutritional deficiency. It often improves, although persistent or recurrent forms occur.
- Cicatricial (scarring) alopecia: Conditions in which inflammation destroys follicles and replaces them with scar tissue, causing permanent hair loss in the affected areas.
A therapy designed to modify androgen activity does not address every autoimmune or inflammatory cause, nor can it simply revive follicles destroyed by scarring. Furthermore, the molecular signalling pathways and hormones involved in hair growth serve essential roles elsewhere in the body. Altering them requires careful assessment of benefits and risks.
4. Can Shampoo Influence Hair Loss?
Separating cosmetic benefits from follicular biology is vital.
A shampoo is primarily designed to cleanse the scalp and hair, lifting sebum and environmental residue. Rinse-off products have a short contact time, but contact time alone does not tell us whether an ingredient can penetrate the skin or influence a follicle. Demonstrating absorption is also not the same as demonstrating a clinically meaningful reduction in hair loss. That requires reliable studies of the finished product used as intended.
Caffeine Shampoos
Laboratory studies of human hair follicles grown outside the body have found that caffeine can influence follicular growth under experimental conditions. However, laboratory findings do not automatically translate into measurable clinical outcomes in people using a shampoo.
On 28 March 2018, the UK's Advertising Standards Authority (ASA) assessed evidence submitted for an Alpecin caffeine shampoo advertisement claiming that it could “help to reduce hair loss”. The ASA concluded that the evidence did not substantiate that specific claim for the advertised product as used by consumers.
That ruling does not prove caffeine can never have an effect. It illustrates why laboratory findings, consumer impressions and studies of different formulations cannot automatically substantiate a particular shampoo's claims.
Botanicals & Biotin
Ingredients such as saw palmetto, rosemary oil and various vitamins regularly feature in hair-care formulations, but the quality of clinical evidence varies significantly between compounds and preparations.
A 2015 trial compared a topical rosemary oil preparation with 2% minoxidil over six months. Both groups showed increased hair counts at six months, with no statistically significant difference between groups. However, there was no placebo group. One comparison does not establish that rosemary is equivalent to minoxidil generally, and the findings should not be transferred to a rinse-off rosemary shampoo.
A systematic review of saw palmetto reported encouraging findings but also a lack of robust, high-quality data. Studies of oral supplements and particular topical preparations do not establish that every product containing the ingredient will have the same effect.
Biotin, while essential to normal metabolic function, has not been established as an effective hair-loss treatment in otherwise healthy individuals without a relevant deficiency. A review of its use found insufficient evidence to support routine supplementation in healthy people.
Well-formulated hair-care products can help condition the hair fibre and reduce breakage, giving hair a fuller, healthier appearance. But minimising shaft breakage is a cosmetic outcome, not a reversal of follicular miniaturisation.
5. Evidence-Based Treatments for Certain Types of Hair Loss
For individuals exploring treatment, the first step is identifying the cause. The options below are examples, not a complete list, and are not suitable for every form of hair loss.
Topical Minoxidil
Topical minoxidil is an established treatment for male and female pattern hair loss. Clinical trials and systematic reviews support its ability to improve hair growth in some patients, although it does not work for everyone.
Benefits generally depend on continued use. Suitability, possible side effects and product instructions should be discussed with a pharmacist or qualified healthcare professional.
Consult the NHS hair loss guide for an overview of treatment options.
Oral Finasteride
Finasteride is a prescription 5-alpha-reductase inhibitor that reduces DHT production and is used for suitable men with male pattern hair loss.
It is not suitable for everyone. The UK Medicines and Healthcare products Regulatory Agency (MHRA) warns about psychiatric and sexual side effects, including reports of sexual dysfunction persisting after treatment has stopped. Anyone considering it should discuss benefits, risks and their medical history with the prescriber and read the patient information supplied with the medicine.
Further information is available from the NHS finasteride guide and the MHRA safety update.
Surgical Hair Transplantation
A hair transplant moves existing hair follicles from a donor region, typically the back of the scalp, into areas of thinning.
A transplant redistributes existing follicles; it does not generate new ones. It is a surgical procedure requiring assessment of suitability and discussion of risks, rather than a universal solution for hair loss.
The NHS hair transplant guide explains the main procedures and considerations.
6. Clinical Evaluation for Women
Hair loss in women deserves careful medical assessment rather than assumptions about its cause.
Diffuse thinning, increased shedding and a receding hairline are not interchangeable patterns. Female pattern hair loss commonly involves thinning over the top of the scalp, while the frontal hairline often remains relatively preserved.
Other causes of hair loss include shedding after childbirth or illness and scarring conditions such as frontal fibrosing alopecia, which can affect the front hairline. Different conditions can also occur together.
The British Association of Dermatologists provides information on female pattern hair loss, telogen effluvium and frontal fibrosing alopecia.
7. Looking Ahead
Scientists continue to investigate hair-follicle stem cells, ways to grow and maintain dermal papilla cells in the laboratory, and molecular signals such as the Wnt/β-catenin pathway, which helps regulate follicle development and regeneration.
Recent research also explores extracellular vesicles, including exosomes: tiny particles released by cells that carry biological signals. Laboratory and animal findings, alongside early clinical studies, have generated interest, but they should not be confused with proof of a reliable, universally effective treatment.
A 2026 systematic review of regenerative approaches identified encouraging clinical findings, while highlighting differences between study methods, limited long-term data and the need for larger controlled trials and extended follow-up.
These avenues offer possibilities for future research, not a promise that a universal cure is imminent.
For now, no single treatment resolves every cause of hair loss.
A genuine understanding of hair care begins not with marketing promises of overnight transformation, but with an appreciation for human biology, realistic expectations, and compassion for how we all experience change.
APPLE & BEARS believes that understanding the human body is part of appreciating the diversity of human beauty.
Whether our hair is abundant, thinning or absent, it does not determine our worth or diminish our individuality.
Scientific References and Further Reading
Advertising Standards Authority (28 March 2018). Ruling on Dr Kurt Wolff GmbH & Co KG t/a Alpecin.
Fischer, T. W., Hipler, U. C., & Elsner, P. (2007). Effect of caffeine and testosterone on the proliferation of human hair follicles in vitro. International Journal of Dermatology.
A Review of the Use of Biotin for Hair Loss (2017).
Panahi, Y., et al. (2015). Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial. Skinmed.
Natural Hair Supplement: Friend or Foe? Saw Palmetto, a Systematic Review in Alopecia.
The effectiveness of treatments for androgenetic alopecia: A systematic review and meta-analysis (2017).
NHS. Hair loss; About finasteride; Hair transplant.
British Association of Dermatologists. Female pattern hair loss; Telogen effluvium; Frontal fibrosing alopecia; Central centrifugal cicatricial alopecia.
Wnt10b Regulation of Hair Follicle Development, Regeneration, and Skin Diseases (2025).
Editorial Disclaimer
This article is published for general educational and informational purposes and draws upon published research, including laboratory, animal and early clinical studies whose findings may not apply directly to routine treatment. APPLE & BEARS is a British body-care brand, not a medical authority. This article is not a substitute for professional medical advice, diagnosis or treatment. For individual concerns about hair loss or treatment suitability, consult a qualified healthcare professional.
