How to choose a cleanser — by criteria, not by brand

The best cleanser isn't a particular brand. It's one that lifts the day's sebum and sunscreen while leaving the mildly acidic film your skin already wears. So instead of memorizing product names, judge a cleanser by three things: how acidic it is (pH), what it cleans with (surfactant), and how much it strips (strength).

Ask "which cleanser is good?" and the answer usually comes back as a product name. Yet the same product suits one person and leaves another tight. The answer lives in the criteria, not the label.

What makes a cleanser good?

A cleanser's job is simpler than it looks: remove the day's sebum, dust, and sunscreen. Trouble starts when it also strips what the skin was already wearing. So rather than memorizing rankings, look at three things — how acidic it is (pH), what it cleans with (surfactant), and how much it removes (strength). A cleanser's job isn't to add anything; it's to pare back the day while leaving what belongs to the skin.

Does a low-pH cleanser really help?

Healthy skin sits at a surface pH on average below 5 (Lambers et al., 2006). That acidic film holds water and keeps a friendly microbial balance. A strongly alkaline cleanser — soap sits around pH 9 to 10 — briefly disrupts it, which is what leaves skin tight and dry after washing. A cleanser in the mildly acidic to neutral range asks less of your barrier. How washing ties into barrier and water loss is covered in what TEWL is. If skin feels tight after washing, it's often a sign the pH doesn't suit it — not that you needed more cleansing.

Why does the surfactant matter?

Surfactants are what actually let a cleanser carry oil away in water. But they vary widely in harshness. Strong ones like SLS (sodium lauryl sulphate) also bind to the proteins and barrier lipids of the outer skin and rinse them away, weakening the barrier (Ananthapadmanabhan et al., 2004). Milder ones — amino-acid and amphoteric surfactants such as cocoyl glycinate or cocamidopropyl betaine — lift grime while disturbing the barrier less. It isn't how squeaky-clean it feels, but what it cleans with, that decides the strain on your barrier.

Is stronger cleansing better?

It's easy to read a squeaky, tight feeling as proof of cleansing power, but that squeak can mean the sebum film came off too. The strength you need matches what's actually on your face that day: a little more after sunscreen or oil-based makeup, less on a bare-skin day. Wash too hard and skin makes more oil to make up for feeling stripped. Why over-washing raises oil is in why oily skin is often dehydrated, and oil or double cleansing on heavy days is in oil cleansing and blackheads. Strength isn't best at its maximum; it's best at exactly what the day leaves to remove.

So, how to choose a cleanser

There is no single best cleanser — only one that suits your skin and the face you're washing that day. Mildly acidic, a gentle surfactant, and only as much strength as the day calls for: with these three you can choose without any brand ranking. Cleansing is the first step of a routine and the ground everything else sits on, so before stacking steps, it's worth making the wash itself a gentle paring-back. On trimming steps overall, see why you don't need a 10-step routine. The best wash isn't the strongest one; it's the one that removes only as much as the day left behind.

One small step

• Check the back of the label for a mildly acidic pH or a gentle surfactant (cocoyl-, -betaine).
• If skin feels tight within five minutes of washing, switch to a gentler cleanser.
• Double cleanse only at night after sunscreen or makeup; one cleanse is enough in the morning or on a bare-skin day.
• Wash with lukewarm water rather than hot.