A damaged skin barrier: signs, causes and repair
Stinging, tightness and flaking usually mean a stripped barrier. The signs, the causes, a 14 day plan built on 3 products, and when to see a doctor.
7 min read
Guides
Everything explained, with numbers.
24 guides across four pillars. Each one answers its question in the first paragraph, gives figures you can use and names its sources. Where a tool on this site fits the topic, the guide points to it.
Skincare 6 guides
Routines, barrier, sun and the questions a mirror asks
Skincare
Skincare
Adult acne after 25: why it happens and what works
Adult acne after 25 is mostly a female pattern. What a 12 week first line course contains, and the point at which it belongs to a dermatologist.
8 min read
Skincare
How much sunscreen a face needs: the 2 mg per square centimetre rule
SPF is measured at 2 mg per square centimetre. What that dose looks like on a face, how little people really apply, and how to close the gap.
8 min read
Skincare
How often to exfoliate: by skin type and acid
Start at 1 night a week. An EU committee suggested 4 percent leave-on glycolic acid at pH 3.8, and pH does more to your skin than the percentage.
8 min read
Skincare
In what order to apply skincare: the layering rules
Cleanse, treat, moisturise, sunscreen. The 4 step order, the 20 to 30 minute gap medicated creams need and why coverage beats sequence.
7 min read
Skincare
Skin purging or a breakout: how to tell them apart
Purging or a breakout? Where the spots sit, when they start, and why week 6 is the honest checkpoint, with the point at which you stop the product.
8 min readIngredients 6 guides
What the actives do, at which concentration, and how fast
Ingredients
AHA or BHA: glycolic, lactic and salicylic acid compared
AHA acts on the surface, BHA inside the pore. Europe advises 4 percent glycolic acid at pH 3.8 or above and caps salicylic acid at 2.0 percent.
8 min read
Ingredients
Hyaluronic acid: molecular weight and how to use it
In ex vivo human skin, chains of 20 to 300 kDa crossed the stratum corneum and 1000 to 1400 kDa did not. What the trials really measured.
8 min read
Ingredients
Mineral or chemical sunscreen filters: how they work
Zinc oxide reflects 4 to 5 percent of the UV reaching it and absorbs the rest. The EU allows 30 filters, the US monograph 16, and the blood data expla
8 min read
Ingredients
Niacinamide: what 2 to 5 percent actually does
At 2 percent it lowered sebum in 100 Japanese subjects; spots needed 5 percent. The trial numbers behind niacinamide, and the vitamin C myth checked.
8 min read
Ingredients
Retinol, retinal or tretinoin: strengths, conversion and results
Retinol, retinal and tretinoin compared: conversion steps, the 0.3 percent EU cap, irritation rates and how long each one takes to work.
8 min read
Ingredients
Vitamin C serums: forms, concentration and stability
L-ascorbic acid enters skin only below pH 3.5, and pig skin studies cap uptake at 20 percent. What derivatives do, and what 12 week trials show.
8 min readBeauty 6 guides
Makeup, hair and nails, with the evidence and the expiry dates
Beauty
Fragrance allergens in cosmetics: what must be on the label
An EU label must name a fragrance allergen above 0.001 percent in a leave-on product. A 2023 regulation took the list from 24 substances to 80.
8 min read
Beauty
Gel manicures and UV lamps: what the evidence shows
A curing lamp emits ultraviolet A at about 7.5 milliwatts per square centimetre. What is measured, what is modelled and what nobody has counted yet.
8 min read
Beauty
Hair loss in women: shedding, pattern loss and what helps
Losing 50 to 100 hairs a day is normal. How telogen effluvium differs from pattern hair loss, which tests matter, and when to see a doctor.
8 min read
Beauty
Hair porosity: the test and what it changes in your care
Porosity is a practical idea, not a clinical measure, and the float test fails. What the 6 to 10 cuticle layers do and the care that follows.
8 min read
Beauty
Skin undertone: how to find yours and match a foundation
Undertone is the red to yellow axis, not depth. Why a tan does not change it, why olive skin is sold pink shades, and a 10 minute jawline test.
8 min read
Beauty
When make-up expires: the open jar symbol and 30 months
In the EU, a cosmetic that keeps for over 30 months carries the open jar symbol instead of a date. What 6M or 12M counts from, and when to throw it ou
8 min readAesthetics 6 guides
Treatments explained: what they do, what they cost you in downtime, and how to choose who does them
Aesthetics
Botulinum toxin injections: onset, duration and risks
Botulinum toxin starts working 1 to 2 days after injection and lasts about 3 to 4 months. Doses, side effects, contraindications and choosing an injec
7 min read
Aesthetics
Chemical peels: superficial, medium and deep
Superficial peels heal in 1 to 7 days, medium peels in 7 to 14 and deep peels in 14 to 21. The acids, the depths, the risks and who may perform them.
8 min read
Aesthetics
How to choose an aesthetic practitioner: the checklist
Rules differ by country. The registers to check, the 7 questions to ask, the red flags, and why hyaluronidase should be in the building.
9 min read
Aesthetics
Hyaluronic acid fillers: risks, red flags and reversal
How hyaluronic acid fillers work, what 6 to 18 months really means, the red flags of vascular occlusion and what hyaluronidase can undo.
8 min read
Aesthetics
Laser hair removal: sessions, skin types and results
A first session takes 10 to 25 percent of the hair and a course runs 4 to 6 sessions at 4 to 6 week intervals. Reduction, not removal.
8 min read
Aesthetics
Microneedling: evidence, sessions and downtime
Microneedling for acne scars usually means 3 to 5 sessions 2 to 4 weeks apart. What the trials show, how long the redness lasts and who should not hav
8 min read