Guides
What your skin is doing, and what to do about it.
Plain answers to the questions people type at midnight: why skin feels tight after washing, whether it is dry or dehydrated, what a toner is for, which acids can share a routine. Every number in these pages points at a study you can open. Start with your skin, or search for what it is doing.
Start with your skin
Routine guide
Dry and dehydrated skin
Tight after washing, flaky in patches, drinks moisturizer by noon.
9 min read
Routine guide
Oily and congested skin
Shine by lunch, pores you can see, breakouts that keep coming back.
9 min read
Routine guide
Dull and uneven skin
Looks tired even when you are not, patchy tone, marks that outstay the spot.
9 min read
Routine guide
Lines and firmness
The first lines that stay after you stop smiling, skin that has lost its bounce.
9 min read
Routine guide
Sensitive and reactive skin
Stings, flushes or flares at products it used to take without comment.
9 min read
Ask it in your own words
Type what your skin is doing, in your words, or pick a tag. Results appear as you type; every one is a guide on this page.
Symptoms
Your skin
The step
The active
Topics
Questions we get asked
One question per guide, answered in the first paragraph and then explained. The sources are at the bottom of each one.
Dry and dehydrated skinGuide
Dehydrated Skin vs Dry Skin, and How to Tell Which You Have
Dry skin is short of oil. Dehydrated skin is short of water, and can be oily at the same time. The signs that separate them, a sink test, and what each needs.
7 min read · 6 sources
Dry and dehydrated skinGuide
How to Use Hyaluronic Acid Serum So It Actually Hydrates
On damp skin, before moisturizer, sealed within a minute, morning and night. Why each of those matters, what molecular weight changes, and when it can backfire.
7 min read · 5 sources
Dry and dehydrated skinGuide
Why Your Skin Feels Tight After Washing (and How to Make It Stop)
That pulled, squeaky feeling thirty seconds after you rinse is your cleanser taking more than dirt. What it took, why moisturizer only patches it, and the fix.
6 min read · 6 sources
Oily and congested skinGuide
Skin Purging vs Breakout: How to Tell Which One You Have
Purging is congestion that was already forming, brought up faster by an acid or a retinoid. Where the spots are and how long they last tell you which it is.
7 min read · 5 sources
Dull and uneven skinGuide
Can You Use Glycolic Acid and Vitamin C Together?
Yes. Vitamin C in the morning, glycolic acid on its two or three evenings, and they never meet. Why the pH worry is mostly about pure ascorbic acid.
6 min read · 6 sources
Dull and uneven skinGuide
How Often Should You Exfoliate Your Face?
Two or three evenings a week with a 5% glycolic acid toner is the answer for most skin. Here it is by skin type, with the signs you have overdone it.
7 min read · 6 sources
Dull and uneven skinGuide
How to Fade Acne Marks (Dark Spots and Red Marks After Breakouts)
Marks are flat pigment or redness left after a breakout; scars are texture. Stop the inflammation, wear sunscreen, then vitamin C and glycolic acid.
7 min read · 7 sources
Lines and firmnessGuide
Retinol Alternatives: Bidens Pilosa vs Bakuchiol vs Retinol
How two plant alternatives compare with retinol on evidence, irritation and sun. Bakuchiol has a human trial against retinol; Bidens pilosa has cell culture.
7 min read · 5 sources
Sensitive and reactive skinGuide
How to Fix a Damaged Skin Barrier (and How Long It Takes)
A damaged barrier stings, flakes and flushes at products it used to tolerate. What broke it, the three-step repair routine, what to stop, and how many weeks.
7 min read · 12 sources
Sensitive and reactive skinGuide
Is Fragrance in Skincare Bad? What the Label Means and Who Should Avoid It
Not bad for everyone, but among the most frequent causes of contact allergy to cosmetics. What parfum, unscented and fragrance-free mean, and what to check.
7 min read · 3 sources
Every skinGuide
How Long Does It Take for Skincare to Work?
Hydration shows in days, texture and tone in 8 to 12 weeks, pigment in 12 to 24, lines in 12 or more. Why the skin cycle sets that clock and when to give up.
7 min read · 10 sources
Every skinGuide
How to Layer Skincare: The Order That Actually Matters
Thinnest to thickest, water before oil, actives on clean skin, moisturizer last and sunscreen over it by day. The order, the pairs to separate, and why.
7 min read · 7 sources
Every skinGuide
What Does Toner Do? The Three Kinds, and Which One You Need
A toner is the water step between cleansing and serum. It hydrates, exfoliates or clears pores depending on what is in it. The alcohol kind is the one to skip.
7 min read · 6 sources
What is in the bottle
The actives in the range, one page each: what the ingredient does, at what strength, what the trials found, and which of our formulas carries it.
Sensitive and reactive skinIngredient
Aloe Vera for Skin: What the Leaf Juice Does and What a Trial Measured
Aloe leaf juice is a humectant. In a trial it raised the water content of the outer skin without changing water loss, so it hydrates but does not seal.
5 min read · 3 sources
Lines and firmnessIngredient
Bidens Pilosa for Skin: The Plant Retinol Alternative, Explained
Bidens pilosa is a daisy-family herb whose extract acts on the same retinoid receptors as retinol. What the cell-culture study found, and what is not known.
6 min read · 5 sources
Every skinIngredient
Caffeine for Puffy Eyes: What Eye Patches Do and How Long It Lasts
Topical caffeine constricts small vessels and reduces fluid build-up, which is why it is in eye patches. The result is a de-puffed morning, nothing structural.
5 min read · 2 sources
Sensitive and reactive skinIngredient
Centella Asiatica (Cica) for Skin: What It Does and What the Evidence Is
Centella asiatica is the plant behind cica skincare. Its triterpenes are anti-inflammatory and support repair, which is why it is used on sensitive skin.
5 min read · 2 sources
Dull and uneven skinIngredient
Ferulic Acid for Skin: What It Does Next to Vitamin C
A plant antioxidant that stabilizes vitamin C and, in pig skin, doubled a vitamin C and E solution's photoprotection. What that study did and did not test.
5 min read · 3 sources
Every skinIngredient
Glycerin
The humectant with the hardest trial behind it. What glycerin does in the outer layer, the four-week barrier study, and why it is in cleansers and creams alike.
6 min read · 4 sources
Dull and uneven skinIngredient
Glycolic Acid for Skin: What It Does and How Often to Use It
The smallest AHA. It loosens dead surface cells so they shed; at 5% it improved texture and discoloration against placebo. Two or three nights a week.
6 min read · 5 sources
Dry and dehydrated skinIngredient
Hyaluronic Acid
A humectant your skin makes that binds many times its weight in water. What it does in the outer layer, what the 60-day trial found, and which size matters.
6 min read · 4 sources
Dry and dehydrated skinIngredient
Jojoba Oil for Skin: A Liquid Wax That Behaves Like Sebum
Jojoba is a liquid wax, not an oil, and close to human sebum. Review evidence calls it anti-inflammatory and well tolerated, with support for barrier repair.
5 min read · 3 sources
Every skinIngredient
Niacinamide: What It Does for Skin, and What the Trials Found
Niacinamide is vitamin B3. It strengthens the barrier, calms redness, evens tone and lowers sebum, and it has human trials at 2% and 5% behind each of those.
6 min read · 4 sources
Oily and congested skinIngredient
Salicylic Acid: What It Does for Skin, and How Often to Use It
Salicylic acid is the oil-soluble exfoliating acid, so it clears inside the pore rather than only at the surface. What the trials found and how often to use it.
5 min read · 5 sources
Dull and uneven skinIngredient
Vitamin C (Ascorbyl Glucoside) for Skin
Ascorbyl glucoside is vitamin C bonded to glucose so it stays stable and does not sting; skin converts it back. What it trades for that, and what trials found.
6 min read · 6 sources
Oily and congested skinIngredient
Zinc PCA: What It Is, What the Study Showed, and What Is Positioning
Zinc PCA is the zinc salt of a molecule skin uses to hold water. Its published evidence is one cell-culture study on collagen; the sebum claim is positioning.
5 min read · 3 sources
Rather not read?
Seven questions about what your skin does, not what you own, and you get the three formulas that treat it. Sixty days to find out, full refund, keep the bottles.