The Science of Hair

How Long Until You See Results? A Realistic Month-by-Month Hair Growth Timeline
The earliest you can fairly judge any hair intervention is three months; the honest assessment point is six. A physician lays out the month-by-month biology — the early shed, the first honest signals, and how to photograph progress so your data is usable. Lire plus...
Hair Loss After Illness, Surgery, or High Fever: Understanding Acute Telogen Effluvium
Heavy shedding three months after a fever, surgery, or COVID is usually acute telogen effluvium — self-limiting, and your follicles are resting, not lost. Lire plus...
Vitamin D and Hair Loss: What the Receptor Research Actually Shows
The follicle needs the vitamin D receptor — but largely not the vitamin. What the knockout research really proves, what human studies show, and why megadosing hurts. Lire plus...
Ferritin and Hair Loss: The Blood Test Your Doctor Probably Did Not Order
A normal CBC does not rule out iron deficiency, and hair feels empty reserves first. Why ferritin is the number that matters — and why you must test, not guess. Lire plus...
Why Most Hair Serums Do Not Work: The Formulation Science of Getting Actives Into the Follicle
The 500-Dalton rule, the follicular reservoir, and why the same active in two vehicles is two different products. Delivery engineering, explained by a formulator. Lire plus...
Oxidative Stress and the Hair Follicle: Why Antioxidants Matter More Than You Think
The follicle is a metabolic furnace, and furnaces produce exhaust. How oxidative stress shortens anagen, kills matrix cells, grays hair — and what the evidence supports. Lire plus...
5-Alpha Reductase Explained: How Pharmaceutical and Botanical DHT Inhibition Actually Differ
Two isoforms, two tissue addresses, and an honest ledger: what finasteride and dutasteride do, what they cost, and what a local, reversible approach trades for. Lire plus...
Seborrheic Dermatitis and Hair Loss: When Inflammation Costs You Density
Seborrheic dermatitis is a medical condition — and the hair loss it causes is usually reversible. The mechanism, the standard of care, and when to see a dermatologist urgently. Lire plus...
Oily Scalp, Buildup, and Thinning Hair: The Connection Nobody Explains
Oily scalp and thinning travel together because gland and follicle answer the same androgen signal. Why washing harder fails, and what a regulated scalp needs. Lire plus...
Do Hair Growth Shampoos Work? Caffeine, Ketoconazole, and What a Shampoo Can Realistically Do
Caffeine and ketoconazole have real science — and a 90-second rinse cannot deliver it. What a shampoo genuinely does, and where regrowth expectations belong. Lire plus...
Red Light Therapy for Hair Growth: Caps, Combs, and What the Evidence Supports
Photobiomodulation is real and modest. A physician explains the mechanism, the sham-controlled trials, what FDA cleared actually means, and where light fits. Lire plus...
How MD Products Are Actually Tested: The Quality File
The actual quality chain behind MD products — laboratories, standards, report numbers, dates — and, at every layer, what that layer does not prove. Lire plus...
What "Physician-Formulated" Should Mean — And How to Check
Physician-formulated has no legal definition. Five questions that separate real formulation from a licensed name — applied in public to MD HAIR itself. Lire plus...
Why We Write "Supports the Appearance Of" — And What It Actually Means
That careful phrase on our labels is not a hedge. It is the outer edge of a legal category — and the honest account of where the line runs and why. Lire plus...
Cosmetic, Supplement, or Drug? The Three Categories That Explain Everything
US law sorts every hair product into cosmetic, supplement, drug or device — by intended use, not ingredients. The map that makes every label legible. Lire plus...
Ergothioneine: The Antioxidant You Have Not Heard Of
A fungal-origin antioxidant your body cannot make but keeps a dedicated transporter for. What ergothioneine is, why formulators use it, and where the evidence stops. Lire plus...
Drug-Free and Natural Are Not the Same Word
Natural is a marketing word with no legal definition. Drug-free is a checkable claim about regulatory category — and you can verify it in five seconds. Lire plus...
Microneedling for Hair Loss: What the Research Shows and How to Do It Safely
The mechanism, the honest evidence, and the safety rules that matter: depth, frequency, device hygiene, and why actives never go on freshly needled skin. Lire plus...
12 Questions to Ask Before You Buy Any Hair Loss Product
A physician's checklist for cutting through hair-product marketing — then applied, in public, to her own products, including the answers she'd rather not print. Lire plus...
What "Clinically Tested" Actually Means on a Hair Product Label
Tested vs proven, the evidence ladder, how before/after photos are staged — and a physician applying the same harsh standard to her own products' studies. Lire plus...
Every Hair Loss Treatment, Ranked by Evidence: A Physician's Honest Guide
Finasteride, minoxidil, LLLT, botanicals, PRP, supplements — a physician ranks every major option by evidence strength, including the drugs she doesn't sell, and explains why the top-ranked one is often the wrong choice for you. Lire plus...
Male Pattern Hair Loss: The Drug-Free Options, Honestly Assessed
Finasteride works — and there are documented reasons some men decline it. A physician's honest guide to the Norwood scale, the drugs, and what a drug-free stack really offers. Lire plus...
Hair Transplants: When They Actually Make Sense
Donor dominance, FUE vs FUT, the fixed donor budget, why good surgeons decline young patients — and the one question most transplant patients forget to ask. Lire plus...
Natural DHT Blockers: What the Science Supports, What It Doesn't
Saw palmetto, pumpkin seed oil, EGCG, zinc, pygeum — a physician reads the actual trials, with effect sizes instead of adjectives, and explains why topical vs oral changes everything. Lire plus...
PRP for Hair Loss: What It Costs, What It Does, and What to Ask a Clinic
An honest guide to platelet-rich plasma for hair loss: the mechanism, the evidence, the standardisation problem, real costs, and nine questions for any clinic. Lire plus...
Breakage or Hair Loss? How to Tell the Difference — and What Hard Water and Heat Are Doing to Your Hair
A shed hair has a bulb; a broken hair doesn't. A physician's ninety-second test — plus what hard water, chlorine, heat, and tight styling actually do to hair. Lire plus...
Do Plant Stem Cells Work in Hair Products? Read the Label
What plant stem cells actually means, why a plant name on a label tells you almost nothing, and why a narrow assay band beats a big potency number. Lire plus...
Does Rosemary Oil Actually Work for Hair Growth? A Physician Reads the Evidence
A physician reads the rosemary oil evidence honestly: what the 2015 trial showed, its four real limitations, safe dilution, and when a formulated serum makes more sense. Lire plus...
Follicle Miniaturization, Step by Step
Pattern hair loss is not follicle loss — it is downgrading. The eight-step miniaturization sequence, and where intervention is still plausible. Lire plus...
How Often Should You Wash Thinning Hair? A Physician Settles the Question
Washing doesn't cause hair loss — it collects hairs that already finished their cycle. A physician explains teloptosis, wash frequency by scalp type, and wet-hair care. Lire plus...
Birth Control and Hair Loss: Starting, Switching, and Stopping the Pill
How hormonal contraception affects hair in both directions — the progestin androgenicity spectrum, post-pill shedding, and how to support follicles through the transition. Lire plus...
Premature Ovarian Insufficiency and Hair Loss: When Menopause Arrives Decades Early
POI delivers the follicular biology of menopause decades early. What it is, why it affects hair, and how to support your follicles alongside medical care. Lire plus...
The MD® Story: How a Practising Physician Built a Hair Line
How a practicing OB/GYN built a physician-owned formulation company — and what 'physician-formulated' should actually mean. Lire plus...
How I Evaluate Hair Loss: The Questions and Labs I Wish Every Woman Brought to Her Doctor
The exact history questions, visual assessment, and comprehensive lab panel Dr. Susan Lin believes every woman with hair loss deserves. Bring it to your appointment. Lire plus...
Anagen, Catagen, Telogen: The Hair Cycle, Properly Explained
Anagen, catagen, telogen, exogen — the four phases, the three-month reporting lag, and the arithmetic behind the 90-day assessment rule. Lire plus...
DHT, Explained: The Hormone Behind Pattern Hair Loss — in Plain Language
What DHT actually is, why it grows beards but shrinks scalp hair, how the two enzyme isoforms differ, and how to read DHT-blocker marketing with skepticism. Lire plus...
Dermal Papilla Cells: The Cells That Decide Your Hair's Future
The dermal papilla decides how long your hair grows and how thick it is — and it is the exact cell type where the published verbascoside research was run. Lire plus...
Lilac Stem Cell Extract: Why MD HAIR Is Built On It
Why the MD® line sources verbascoside from lilac plant cell culture rather than wild-harvested extract: standardization, purity, sustainability, and traceability. Lire plus...
Sulfates, Silicones, and Your Scalp: What Matters, What's Marketing
A formulating physician separates real chemistry from label marketing: who genuinely needs sulfate-free, what silicones do and don't do, and what matters for thinning-prone scalps. Lire plus...
When to See a Dermatologist About Your Scalp
The scalp findings that warrant a dermatology appointment, what the visit actually involves, and how to get the most from a short consultation. Lire plus...
Dandruff vs Dry Scalp: How to Tell Which One You Have
Flaking is a symptom, not one condition. How to tell seborrheic flakes from dry-scalp flakes, when to see a dermatologist, and the calm-first routine. Lire plus...
Your Part Line Is Skin: Scalp Sun Damage and Why It Matters
The scalp burns, accumulates photodamage, and hides skin cancers until late. Why your part line needs protection, and what actually works. Lire plus...
Can Thinned Hair Grow Back? The Reversibility Window, Explained
Whether thinned hair can recover depends on one distinction: miniaturized follicles versus fibrosed ones. A physician explains the reversibility window. Lire plus...
Itchy Scalp but No Dandruff: What Else It Could Be
Itch without flakes usually isn't dandruff. Contact allergy, scalp dysaesthesia, folliculitis, residue and the itch-scratch loop — and when to see a doctor. Lire plus...
Hair Supplements: What Actually Has Evidence — and What to Skip
A physician's honest, ingredient-by-ingredient guide to hair supplements: what has evidence, what only helps the deficient, and what to skip entirely. Lire plus...
Peptides and Hair: How Biotinoyl Tripeptide-1 and Peptide Complexes Support Aging Follicles
What cosmetic peptides actually are, how signal peptides like Biotinoyl Tripeptide-1 interact with the dermal papilla, and why concentration and delivery decide everything. Lire plus...
Traction Alopecia: The Hair Loss You Can Actually Prevent
Traction alopecia is preventable and, caught early, reversible. The mechanism, the fringe sign, and how to reduce tension without giving up your style. Lire plus...
Why I Formulate Drug-Free: A Physician's Perspective on Treating Hair Loss Without Pharmaceuticals
Dr. Susan Lin on the patients pharmaceutical hair-loss options exclude, and the suitability-first philosophy behind the drug-free MD HAIR line. Lire plus...
Insulin Resistance, Metabolic Syndrome and Thinning Hair
How chronically high insulin lowers SHBG, raises free androgen at the follicle, and quietly thins hair — and the one blood test that catches it early. Lire plus...
Does Verbascoside Work? What the Cell Studies Actually Show
What published cell research actually shows about verbascoside and the dermal papilla — findings, limits, and why one claim was removed from this article. Lire plus...