What happens to skin between thirty and fifty

You can see the split on your own arm. Compare the skin on the inner upper arm, which has spent fifty years in the dark, with the back of the same forearm. The difference between those two pieces of skin — same person, same age, same genetics — is ultraviolet. Broadly: chronological ageing thins skin, and photoageing coarsens it, mottles it and slackens it. The second is the larger share of what people dislike, and it is the share that responds to treatment.

Expression muscles are used tens of thousands of times a year, and the skin folded over them eventually keeps the fold. There is a transition point in most faces, usually somewhere in the late thirties, where a line that appeared only during expression becomes faintly visible at rest. Before that point, relaxing the muscle prevents the fold from setting. After it, the muscle can be relaxed but the crease in the dermis remains, and softening it needs something else — resurfacing, a very small amount of product in the line itself, time.

That transition is the reason practitioners talk about starting earlier, and it is also the reason the advice is so easily abused. Starting earlier means starting when a line is beginning to persist. It does not mean starting at twenty-four because a campaign called it prevention.

• Dynamic lines — the frown, the forehead, the outer corners of the eyes. Neuromodulators do this predictably and well.
• Pigment and surface texture — sun-induced brown marks, roughness, pores that look larger than they are. A retinoid and daily sunscreen do more here over a year than most people expect; lasers accelerate it.
• Lost volume — hyaluronic acid filler, or more slowly with collagen biostimulators. The result depends far more on where it is placed than on how much of it there is.
• Dermal quality and fine lines — resurfacing, microneedling, retinoids. Slow, cumulative and real.
• Laxity — the honest one. Energy-based devices tighten modestly and temporarily. If the skin envelope is genuinely loose, a surgical answer is the effective answer, and we will say so rather than sell four sessions of something that will not do it.
• Bone — not treatable. It can be compensated for, structurally and carefully, which is a different sentence.

Sunscreen and a retinoid first, for a year, before anything is injected. This is unpopular advice because it is slow and cheap, and it is still the right order. Skin quality is the layer everyone sees first: an evenly toned face with a smooth surface reads younger than a volumised one with mottled, roughened skin.

Then correct what is making it worse. Smoking is the largest modifiable accelerant we see, followed by repeated weight cycling, which empties and refills the fat compartments and stretches the envelope a little further each time. Chronic short sleep shows around the eyes within days. None of this is moralising — it is simply that these things undo the work faster than the work can be done.

Then, if it is still worth doing, treat the structure. Conservatively, in stages, with photographs, and with a willingness to stop.

At thirty-five, most of the useful work is preventive and dermal: sun protection, a retinoid, occasional resurfacing, and a small, well-placed amount of neuromodulator if lines are beginning to persist. Injecting volume at this age is rarely indicated and frequently sold.

At forty-five, volume and structure are usually part of the conversation, skin quality still leads it, and expectations have to be specific. A good outcome is a face that looks like itself on a better week. It is not the face in a photograph from fifteen years ago, and anyone promising that is selling something they cannot deliver.

The most useful thing we can say to someone in this decade is that the changes are slow, and the response to them should be slow as well. Almost nobody regrets having done less. A meaningful share of the consultations we take are with people correcting the opposite.