What scalp care can do, and what it cannot.
The hair growth cycle is measured in months. Most of this category sells results in weeks. These 22 articles explain the difference, with the numbers attached and the sources listed.
The hair cycle
Why hair sheds, on what timeline, and which patterns mean a doctor rather than a product.
- 8 min read
Stress and hair loss: the three-month delay
Hair that falls in October was pushed into rest in July. How stress reaches the follicle, why the shedding arrives late, what a 2021 mouse study showed, and how to tell stress shedding from the other kinds.
Read - 9 min read
Iron, vitamin D, biotin: which deficiencies actually cause shedding
One of these three has strong evidence, one is plausible and under study, and one is a supplement almost nobody needs. A sorting of the nutrients that get blamed for hair loss, with the reviews that back it.
Read - 7 min read
Traction alopecia: the hair loss you can stop
Thinning at the hairline and temples from years of tight styles is the one common form of hair loss that is fully preventable and, caught early, fully reversible. How to recognise it, and the 5 signs it is time to loosen up.
Read - 8 min read
Hair loss: when to stop buying products and see a dermatologist
Nine signs that thinning has left the cosmetic category, what a dermatologist will do in the first appointment, and what to bring so the visit is worth its cost.
Read - 10 min read
Why hair sheds: the scalp, not the strand
Losing 50 to 100 hairs a day is normal. Here is how the growth cycle works, why shedding shows up months after its trigger, and why most hair products treat the wrong surface.
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Scalp care
Buildup, pH, hard water, dandruff, wash frequency: the surface the hair grows from.
- 8 min read
Scalp buildup: what it is, how to tell, and how to clear it
Sebum, dead skin, styling residue and hard-water minerals form a film that most people mistake for greasy hair. The 6 signs, the 4 sources, and a clearing routine that does not strip the scalp raw.
Read - 7 min read
Hard water and hair: what the minerals do, and what they do not
Hard water leaves a film that makes hair rough, dull and tangled. The one controlled study on hair strength found no difference. Here is how to tell if your water is the problem, and the 3 fixes ranked by cost.
Read - 7 min read
How often to wash thinning hair
Washing does not cause shedding, and skipping washes does not prevent it. What frequency actually depends on, a table by scalp type, and why the hair in the drain after a wash is not new loss.
Read - 8 min read
Dandruff vs dry scalp: telling them apart, and why it matters
They both flake and both itch, and the fix for one makes the other worse. A comparison table, the yeast at the centre of it, and what to do when 4 weeks of the right approach has not worked.
Read - 8 min read
Shampoo pH: the number brands do not print
Scalp sits near pH 5.5. Hair near 3.7. Most shampoos test above 5.5, and a 2014 survey found that many popular ones sit far higher. What pH does to the cuticle, how to test a product at home, and why baking soda is a bad idea.
Read - 9 min read
A Korean scalp care routine, step by step
Korean haircare treats the scalp as skin. Four steps, a weekly schedule, the pH detail nobody explains, and an honest account of what the routine cannot do.
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Ingredients
What the studies behind the popular botanicals actually measured, and in what.
- 9 min read
Rosemary oil vs minoxidil: what the one study actually found
A 2015 trial of 100 men is the entire basis for the claim that rosemary oil works as well as minoxidil. Here is what it measured, what it did not, and why a rosemary shampoo is not the same thing as the trial.
Read - 8 min read
Scalp massage and hair growth: what 4 minutes a day did in the studies
A 2016 study of 9 men found thicker hair after 24 weeks of daily massage. A 2019 survey of 340 people found most reported improvement after months of it. What the evidence supports, how to do it, and the limits.
Read - 7 min read
Peppermint oil and hair growth: the mouse study everyone cites
In 2014, peppermint oil outperformed minoxidil in mice. That result is on a thousand product pages. Here is what was measured, why mouse hair is not human hair, and what the tingle actually is.
Read - 12 min read
A glossary of scalp care botanicals, graded by evidence
Twelve botanicals that appear on scalp product labels, each with what it plausibly does in a rinse-off cleanser, what the best available study measured and in what species, and an honest grade from A to D.
Read - 8 min read
Sulfate-free shampoo: what sulfates do, and what they do not
Sulfates do not cause hair loss and are not toxic. They are strong detergents that strip a fragile scalp more than it needs. Who benefits from going sulfate-free, who does not, and how to read the surfactant on a label.
Read - 11 min read
Fermented herbs in Korean haircare: ginseng, centella, green tea, rice water
What fermentation does to a botanical extract, what the evidence supports for four common ingredients, and the two places where the marketing quietly outruns the research.
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Routine and format
Bars against bottles, transition periods, cost per wash, and building a routine that holds.
- 8 min read
The shampoo bar transition period: what is happening, and how to shorten it
Two to three weeks of heavier, waxier hair is the point where most people give up on a bar. Here is the mechanism behind it, how to tell a normal transition from a bar that is wrong for you, and the 4 changes that shorten it.
Read - 8 min read
How to measure hair thinning at home, so you know instead of guess
Memory is a poor instrument and the mirror is worse. Four methods that produce numbers you can compare across months: the photo protocol, the ponytail measurement, the parting width, and a shed count done properly.
Read - 8 min read
How long a shampoo bar lasts, and when to expect results
40 to 60 washes per bar, a cost per wash you can calculate yourself, and a timeline for what changes and when — constrained by how the hair cycle actually works.
Read - 9 min read
Shampoo bar vs liquid shampoo for thinning hair
Liquid shampoo is roughly 80% water. A solid bar is not. Here is what that difference means for a scalp that sheds, what the evidence on sulfates actually says, and what neither format can do.
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