Moisturisers decoded: humectants, emollients, occlusives - and why hyaluronic acid sometimes makes skin drier

Moisturiser is the least glamorous product in a routine and the one that decides whether everything else is tolerable. It does three separate jobs, and most products do one or two of them well.

The three jobs

Ceramides sit slightly apart from this scheme. They are lipids that occur naturally in the skin barrier, and formulations containing them - usually with cholesterol and fatty acids - aim to replace what a damaged barrier is missing rather than simply covering it.

The hyaluronic acid problem

Humectants pull water from wherever it is available. In humid air, that includes the air. In dry air - a heated Delhi winter, a well-air-conditioned office, an aircraft cabin - there is less water outside than inside, so a humectant applied alone can draw moisture from deeper in the skin and let it evaporate.

The fix is not to abandon hyaluronic acid. It is to apply it to damp skin and put something over it: a cream with emollients and an occlusive to hold what the humectant gathered. A hyaluronic acid serum on dry skin with nothing on top is the single most common reason people say it made their skin feel tighter.

Glycerin deserves more respect than it gets. It is cheaper than hyaluronic acid, at least as well studied, and appears near the top of most good moisturisers precisely because it works.

Choosing a texture for the weather you actually live in

• Hot and humid: a gel or lotion with humectants and light emollients. Heavy occlusives feel suffocating and can trap sweat.
• Hot and dry: a lotion or light cream with a real occlusive. Humidity is not going to help you here.
• Winter in the north: a cream, applied to damp skin, plus something richer on hands, elbows and heels.
• Air conditioning all day: treat it as dry weather, regardless of what the season outside is doing.
• Oily skin: still needs moisturiser. Skipping it is what pushes oil production up; a gel-cream is usually the right answer.
• Compromised or actively treated skin: fewer ingredients, no fragrance, ceramides and petrolatum-style occlusives.

What barrier repair actually means

A healthy barrier is corneocytes held in a lipid matrix - the classic bricks and mortar. When that matrix is depleted, water leaves faster and irritants enter more easily, which is what stinging, flaking and reactivity are signalling.

Repairing it is dull and effective: stop the thing that damaged it (usually over-exfoliation or too much retinoid too fast), simplify to a cleanser and a moisturiser, use ceramides and occlusives for two to four weeks, and keep sunscreen on. Nothing else, however well reviewed, works faster than removing the cause.

Claims worth ignoring

• Oil free tells you about texture, not about whether a product suits acne-prone skin.
• Non-comedogenic has no mandatory test behind it; it is a formulation intention.
• 24-hour hydration is a claim about a test protocol, not a promise about your day.
• Natural says nothing about how a formula will behave; plant oils vary enormously and some are highly sensitising.

Buy for texture and season first, ingredients second, brand last. A moisturiser you reapply happily in June is worth more than one you admire in a cupboard.