DHT y caída del cabello: la hormona clave detrás de la calvicie

Dihydrotestosterone (DHT) is converted from testosterone by the enzyme 5-alpha reductase. While DHT is essential during development (driving male sexual maturation), in adulthood it plays a paradoxical role in hair: it promotes body and facial hair growth while shrinking scalp hair follicles.

• Follicle miniaturization: DHT binds to androgen receptors on genetically susceptible hair follicles, triggering a cascade that shortens the growth (anagen) phase and gradually shrinks the follicle. Over multiple cycles, thick terminal hairs become thin, unpigmented vellus hairs.
• Genetic sensitivity: Not all follicles respond to DHT equally. The difference between balding and non-balding scalp is not DHT levels but receptor density. Balding areas have significantly more androgen receptors.
• Scalp DHT levels: Research published in the Journal of Clinical Endocrinology & Metabolism found DHT concentrations in balding scalp tissue are 3-6 times higher than in non-balding areas of the same individual.

This explains why hair transplants work: follicles from the DHT-resistant back of the head retain their resistance when moved to the top of the scalp.

Evidence-based DHT-blocking strategies include pharmaceutical and natural approaches:

Pharmaceutical options:

• Finasteride (1mg oral): Inhibits type II 5-alpha reductase, reducing scalp DHT by approximately 70%. The pivotal 5-year trial showed 90% of men maintained or improved hair count. Side effects (2-4%): decreased libido, erectile dysfunction — typically reversible upon discontinuation.
• Dutasteride (0.5mg oral): Inhibits both type I and type II 5-alpha reductase, reducing DHT by up to 90%. A 2014 trial showed superior results to finasteride for hair count. FDA-approved for prostate enlargement, used off-label for hair loss.
• Topical finasteride: 0.025-0.1% solutions applied to the scalp may reduce systemic DHT by only 20-30% (vs. 70% with oral), potentially minimizing sexual side effects. Emerging evidence supports comparable scalp efficacy.

Natural DHT inhibitors (weaker evidence):

• Saw palmetto: May inhibit 5-alpha reductase. A 2020 meta-analysis found modest benefit in 60% of patients, though far less potent than finasteride.
• Pumpkin seed oil: A 2014 randomized trial showed 40% improvement in hair count over 24 weeks.

Upload your dermatologist's assessment or scalp images to WAYJET's Medical Report Analyzer for personalized treatment guidance.

The safety profile of DHT blockers — particularly finasteride — is a topic of significant debate:

• Clinical trial data: In the original pivotal trials, sexual side effects (decreased libido, erectile dysfunction, reduced ejaculate volume) occurred in 2-4% of men taking finasteride vs. 1-2% on placebo. 97% resolved upon discontinuation.
• Post-finasteride syndrome (PFS): Some users report persistent sexual, neurological, and psychological side effects after stopping finasteride. While acknowledged by some researchers, PFS remains controversial. A 2019 systematic review in JAMA Dermatology found limited evidence for persistent effects but acknowledged the need for larger studies.
• Nocebo effect: A 2021 study in JAAD found that men who were informed about potential sexual side effects were 3-5x more likely to experience them compared to uninformed men receiving the same medication. This suggests psychological expectation plays a significant role.

Practical recommendations:

• Start with the lowest effective dose (1mg finasteride or consider topical formulation)
• Monitor for side effects over the first 3-6 months — if they occur, they typically appear early
• If concerned, discuss dutasteride or topical options with your dermatologist
• Women of childbearing age must not take or handle finasteride due to risk of birth defects in male fetuses