Hair Loss: Why the Diagnosis Has to Come Before the Treatment

This is an English adaptation of a clinical article by Dr. SangYoul Yun — board-certified dermatologist and Medical Director of Delight Dermatology in Gangnam, Seoul — originally published in Korean. Read the Korean original on Naver. Evidence citations were reviewed for this edition.

When hair starts falling, the first questions are usually "what should I take?" and "which shampoo should I use?" Both skip the step that decides everything: what kind of hair loss is this? The same oral medication that works well for pattern hair loss does nothing for autoimmune patchy loss, and the same procedure behaves differently depending on the mechanism underneath.

Four patterns seen most often in clinic

Hair loss is not one condition — the mechanism decides the treatment

Type	Typical presentation	Underlying mechanism
Pattern (androgenetic)	Receding temples or thinning crown in men; widening part in women	Androgen-driven follicular miniaturization with genetic susceptibility
Telogen effluvium	Diffuse shedding weeks to months after a trigger	Follicles pushed into the resting phase by illness, childbirth, rapid weight loss or severe stress
Alopecia areata	Sharply defined round patches, sometimes sudden	Autoimmune attack on the hair follicle
Traction and age-related	Hairline recession at areas of tension; finer shafts overall	Sustained mechanical pull and cumulative follicular aging

What the evidence supports for pattern hair loss

Pattern hair loss has the strongest data of the four. Two 2025 network meta-analyses examined how the conventional options compare. The first, across 33 studies of monotherapy, found oral dutasteride 0.5 mg/day most effective overall; among treatments approved by the US FDA for this indication, topical minoxidil 5% ranked highest for topical use and oral finasteride 1 mg/day highest for oral use, while dutasteride delivered by mesotherapy performed significantly worse than the same drug taken orally (DOI 10.1111/jocd.70320). The second compared conventional treatments with popular over-the-counter alternatives across 24 trials and again confirmed the conventional agents, while placing the alternatives in context (DOI 10.1111/jocd.70483).

Two practical implications follow. First, route of administration is not a detail — the same molecule can perform differently depending on how it is delivered. Second, these are prescription decisions: finasteride and dutasteride require medical assessment, carry contraindications including pregnancy, and are not appropriate to start from an article.

Telogen effluvium: find the trigger first

Diffuse shedding that begins weeks after a stressor usually reflects a temporary shift in the hair cycle rather than permanent follicle loss. The evaluation looks for what pushed the follicles into rest — illness, delivery, crash dieting, thyroid dysfunction or medication changes.

Iron deserves an honest note. A dermatology review of iron deficiency and hair loss concluded there is insufficient evidence to recommend universal iron screening in everyone with hair loss, and equally insufficient evidence for supplementing iron in the absence of anemia; the review's authors nonetheless described screening as reasonable clinical judgment in their own practice (DOI 10.1016/j.jaad.2005.11.1104). In other words: testing can be sensible, but "take iron for hair" is not an evidence-backed universal rule, and excess iron carries its own risk.

Alopecia areata is an immune problem, not a nutrition problem

Round, well-demarcated patches point to an autoimmune process affecting roughly 2% of people worldwide. A 2025 narrative review notes that intralesional corticosteroids penetrate to the level of the follicle and achieve higher success rates than topical steroids in mild-to-moderate disease, that topical steroids are the option for those who cannot tolerate injections, and that recurrence after stopping treatment is common (DOI 10.1007/s13555-025-01421-2). Extensive or rapidly progressive disease is managed differently again, which is why a patch that appears suddenly deserves assessment rather than a shampoo change.

Where scalp procedures fit

Procedural options such as PRP are used as supportive treatment alongside — not instead of — diagnosis-led medical management. Response develops gradually across a course rather than after a single session, and it varies between individuals. Our hair loss treatment page explains how a course is structured here.

What to bring to the first visit

• Timeline: when shedding started and whether it was sudden or gradual.
• Triggers in the preceding six months: illness, surgery, childbirth, weight change, new medication.
• Pattern: photographs of the part line or crown taken in the same light over time.
• Family history and any previous treatments and their effect.

Frequently asked questions

Will a shampoo fix hair loss? Shampoo manages the scalp environment. It does not reverse follicular miniaturization or an autoimmune attack.

Is shedding after childbirth permanent? Post-partum shedding is typically telogen effluvium and usually recovers, but persistent thinning deserves assessment rather than waiting indefinitely.

Can I take finasteride without seeing a doctor? No. It is a prescription medication with contraindications and side-effect considerations that require medical review.

How long before I can judge a treatment? Hair cycles are slow. Meaningful assessment takes months, which is why standardized photographs at the start are so useful.

Reviewed by

Written by Dr. SangYoul Yun, board-certified dermatologist and Medical Director of Delight Dermatology, Gangnam, Seoul. Evidence reviewed 2026-08-04.

Sources

1. Gupta AK et al. Comparative efficacy of minoxidil and 5-alpha reductase inhibitors for male pattern hair loss: network meta-analysis. J Cosmet Dermatol. 2025. DOI 10.1111/jocd.70320
2. Gupta AK et al. Relative efficacy of conventional monotherapies and select over-the-counter products for male androgenetic alopecia. J Cosmet Dermatol. 2025. DOI 10.1111/jocd.70483
3. Gregoire S et al. Local corticosteroids for alopecia areata: a narrative review. Dermatol Ther (Heidelb). 2025. DOI 10.1007/s13555-025-01421-2
4. Trost LB, Bergfeld WF, Calogeras E. The diagnosis and treatment of iron deficiency and its potential relationship to hair loss. J Am Acad Dermatol. 2006. DOI 10.1016/j.jaad.2005.11.1104

Citations retrieved from PubMed. Medical disclaimer: this article is general education, not a diagnosis or a prescription. Hair loss diagnosis and medication selection require an individual medical assessment.