Six questions per issue about loss, scalp health and the things sold to fix them. Every claim carries a grade telling you how much of it rests on controlled evidence.
Six pieces, ordered by where they sit in a clinical conversation rather than by date.
Two drugs have survived decades of controlled trials. Everything else on the shelf is either an adjuvant or a story with a price.
Telogen effluvium is the commonest cause of diffuse hair loss and the most over-investigated. Most of the tests ordered for it change nothing.
Sebum does not “rebound”. Sulfates are not the villain. And the float test cannot tell you your hair's porosity, because nothing can.
The chemistry is genuine and the molecules do what the papers say. The claim that they “repair” hair is where the language quietly slips.
Dandruff and seborrheic dermatitis sit on one spectrum, share one organism, and respond to the same short list of actives.
Graft survival in experienced hands is high. Candidate selection is where results are won, and where most disappointing outcomes begin.
Open each one for what the evidence actually shows.
Sebum output is governed by androgens and gland biology. Nothing in the gland senses surface oil, so there is no feedback loop to train. Hair feels better on day three because a thicker oil film makes it lie flat — accumulation, not adaptation.
The transplanted hair is permanent. The scalp around it is not. Without medical treatment the native hair keeps receding, and the grafted band becomes an island. Surgery rearranges hair; it does not stop the process that removed it.
New cross-links do form, and the fibre is measurably stronger. They do not sit where the original bonds were, and some oxidised cysteines cannot be re-paired at all. The result is improvement, not restoration, and it reverses with the next colour.
The claim is supported by controlled comparisons in people. Effect size and population still matter.
Directionally sound, but the size of the effect is less certain and often overstated in coverage.
Plausible chemistry is not a clinical result. Treat these as hypotheses with a price tag.
This site describes what studies found in populations. It cannot examine your scalp, and a page is not a diagnosis.
If any of these apply, see a dermatologist or your GP before spending money on a treatment.