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Shampoos · serums · oils

Read the back of the bottle, not the front

Shampoos, serums and oils for thinning hair, graded out of ten on the trials behind them rather than the claims on the label. Non-prescription only. Information, not advice — no clinician has reviewed a word of it.

Shampoos, gradedSerums, graded

Nine actives, one ten-point scale, every trial pulled at the source. Two of them have no grade at all, because we could not read a trial to give them one.

Actives, graded
Out of 10
Pyrithione zinc 1%7shampoo · Br J Dermatol 2003
Ketoconazole 1% (2% on prescription)6shampoo · Dermatology 1998
Rosemary oil5leave-on oil · Skinmed 2015
Caffeine4shampoo · Skin Pharmacol Physiol 2017 · ASA 2018
Redensyl, Procapil, AnaGain, Capilia longa4serum · J Cosmet Dermatol 2024
Onion juice3leave-on · J Dermatol 2002
Minoxidil, in a shampoo0shampoo · PubMed · 21 CFR 310.527
Saw palmetto, applied to the scalpn/gserum or shampoo · nothing read at the source
Nanoxidiln/gserum · nothing read at the source

What this site is for

The hair-loss aisle is unusually good at sounding like medicine. Bottles carry molecule names, percentages and the word clinical, and almost none of it is a claim anyone has to stand behind. Latherlogic exists to close that gap in one direction only: for every active you can buy without a prescription, we go and find the trials, read them at the source, and publish what they are — how many people, for how long, paid for by whom, measuring what.

Then we apply one published ten-point scale, the same one to everything, and print the result beside the ingredient rather than beside a brand. Sometimes the answer is that there is nothing to read, and we say that too — two of the nine actives on this site carry no grade at all, including the house active of a company whose links appear on these pages.

What we will not do: invent a percentage, describe a result we did not read, publish a before-and-after photograph, tell you how much of anything to use, or pretend that a shampoo is the answer to a question a doctor has not been asked yet.

The short version, if you are in a hurry

  • No shampoo or serum is approved in the United States as a hair grower, and the two best-evidenced actives are ordinary medicated shampoos sold for a few pounds.
  • The strongest trial in the whole aisle found a hair-count increase slightly less than half the increase on a leave-on drug, and it was published in 2003.
  • Several famous ingredients rest on a single study run by the company selling them.
  • Hair thins for many reasons, most of them invisible from a shelf. A diagnosis is the first purchase worth making, and it is not one of ours.

The whole aisle, side by side, is in the best shampoo for hair loss, graded on published evidence. The leave-on half of it is in the best hair growth serum, graded the same way.

How a grade is built
10 points
Trials in hair loss4

none found · uncontrolled · one controlled · more than one · more than one, independent

Who paid for them2

the seller · unstated · independent of the seller

What was counted2

self-report · investigator rating · hairs counted or measured

Shelf product vs trial2

no · partly · yes

An ingredient we have not read at the source gets no grade at all, and the row says so. Borrowing a score from someone else’s summary would look the same on the page and mean nothing.

Why a scale and not a star rating

A star rating hides the thing that matters. Two ingredients can both look like a six and be nothing alike: one because a controlled trial counted hairs on two hundred scalps, the other because the company selling it ran thirty-two people through sixty days with nobody to compare them against. Splitting the ten points into four questions puts that difference on the page instead of inside our heads.

The fourth question is the one the aisle relies on you not asking: whether the tub on the shelf is the thing that was tested. A trial of a leave-on liquid is not a trial of the shampoo with the same word on the front.

How the grading works

One ingredient at a time

Every ingredient we read →

How to Choose a Hair Loss Product Without Being Sold To

Six questions that survive contact with any product page, worked through on real claims we read in September 2026 — including from the shops this site links.

IngredientSep 15, 2026

Thickening Shampoos: What They Do, Said Plainly

Volumising and thickening shampoos work, at the thing they are actually for. They are cosmetics that change how hair looks in the mirror, and that is not nothing.

IngredientSep 12, 2026

Hair Growth Oils, Graded: Rosemary, Onion, Castor and Pumpkin Seed

Four oils, four very different bodies of evidence — one controlled trial for the wrong condition, one with no untreated group, and two we would not score at all.

IngredientSep 9, 2026

Shampoos That Cause Hair Loss: the Myths and the One Real Case

Sulfates, purple shampoo and switching brands are not why your hair is thinning. One product category was genuinely investigated by the FDA — here is what that found.

IngredientSep 5, 2026

Does Dry Shampoo Cause Hair Loss? What Is Documented

The 2022 benzene recalls were about a propellant, not about hair. Here is what is actually on the record, and what the question usually turns out to be about.

IngredientSep 1, 2026

Minoxidil Shampoo: Why Contact Time Decides What a Wash Can Do

No trial of minoxidil in a rinse-off shampoo came back from PubMed. Here is why the form matters, and the 1989 rule that explains what a bottle is allowed to say.

IngredientAug 28, 2026

Questions people ask in the aisle

Can a shampoo regrow hair?
No shampoo is approved in the United States as a hair grower, and nothing sold as one reaches the top of our scale. The FDA's own guidance says a claim that a product will restore hair growth makes it a drug rather than a cosmetic, and 21 CFR 310.527 treats an over-the-counter product promoted as a hair grower as an unapproved new drug. What two medicated shampoos do have is a controlled trial each showing a measured change in hair: a 1% pyrithione zinc shampoo against a placebo shampoo over 26 weeks (British Journal of Dermatology, 2003), and a 2% ketoconazole shampoo against an unmedicated one (Dermatology, 1998). Both are modest, both are old, and neither is a regrowth promise.
Is ketoconazole shampoo worth buying if I am losing hair?
It is one of the two cheapest things in this aisle with a controlled trial behind it, and the version you can buy without a prescription is not the version that was studied. Piérard-Franchimont and colleagues used a 2% shampoo and reported hair density, hair size and the proportion of anagen follicles improving almost similarly to minoxidil, while writing that the clinical significance awaited a larger controlled study (Dermatology, 1998). The shampoo on a supermarket shelf is 1%, and its own Drug Facts label says it controls flaking, scaling and itching associated with dandruff — it makes no hair-growth claim at all. A 2025 Canadian expert consensus placed ketoconazole shampoo among interventions recommended with near consensus as part of a regimen, not on its own.
Does rosemary oil work as well as minoxidil?
One trial compared them and found no significant difference between the two groups — which is not the same as either one working. Panahi and colleagues randomised 100 people with androgenetic alopecia to rosemary oil or minoxidil 2% for six months, saw no change in hair count at three months, and a significant rise in both groups at six (Skinmed, 2015). There was no untreated arm, so nothing in the design separates the treatments from six months passing. A 2025 Canadian expert consensus lists rosemary oil among interventions it does not recommend, and a 2025 review of alopecia misinformation names it among the remedies commonly touted online without support.
Can a shampoo cause hair loss?
Ordinary shampoo does not cause pattern hair loss, but a specific product can be investigated, and one was. The FDA began receiving voluntary reports of hair loss linked to cleansing conditioners in 2011, announced an investigation in July 2016, and commissioned work at Columbia University in which mice treated over a prolonged period with one of two named cleansing products showed abnormal hair growth cycles — while the agency says it was unable to draw a firm connection between those products and alopecia. Separately, aerosol dry shampoos were recalled in 2022 over benzene in the propellant, which is a contamination question, not a hair-loss one.
What should I do before I buy anything?
Find out why your hair is thinning, because the answer decides whether this aisle is even the right shelf. Thyroid disease, low iron, telogen effluvium after an illness or a birth, alopecia areata, scarring alopecias and the side effects of medicines you already take all thin hair and none of them is treated by a shampoo. A GP or a board-certified dermatologist can tell those apart, and that appointment pays this site nothing. If you have flaking and itching as well, an over-the-counter anti-dandruff shampoo treats that on its own label for a few pounds, and pays us nothing either.