How does polynucleotides work?

A category that does not fill anything. Where filler occupies space, these treatments give the skin either instructions or materials, and then wait for your own cells to do the work. That difference is the reason the results appear over weeks rather than on the day, and the reason they are given as a course rather than as an appointment.

The category covers several genuinely different things. Polynucleotides are fragments of purified DNA that act as a signal to the fibroblasts — the cells that make collagen and elastin — to behave more like younger ones. Amino acid injectables supply the raw materials the skin needs to rebuild its matrix. Bio-remodelling uses a very high concentration of uncross-linked hyaluronic acid that spreads through the tissue rather than staying put, hydrating and stimulating as it goes. Platelet-rich plasma concentrates the growth factors from your own blood. Exosomes are signalling vesicles.

They are frequently sold as interchangeable and they are not. Which one suits you depends on whether your skin needs signalling, materials, hydration or all three — which is an assessment question rather than a menu question.

The common mechanism is fibroblast stimulation. Fibroblasts sit in the dermis and produce collagen, elastin and hyaluronic acid; with age they become fewer and lazier, and the matrix they maintain thins and loses its spring. Every treatment in this category is trying to get those cells working again, by one route or another.

Because you are waiting on cell behaviour rather than on a product, the timeline is biological. Little is visible at two weeks. Change is usually apparent from four to six weeks, continues developing for two to three months after the final session, and the improvement is in quality — firmness, hydration, how light sits on the skin — rather than in shape.

This is also why a course exists. A single session produces a signal; repeated sessions produce a sustained one, and sustained signalling is what changes the tissue. Stopping after one is the commonest reason someone concludes the category does not work.

Short, purified fragments of DNA — most commonly derived from salmon or trout, because that DNA is highly compatible with human tissue and can be purified to a very high standard.

They do not become part of your DNA and nothing about them is genetic in the way the word suggests. They act as a signal: the fragments are recognised by the fibroblasts, which respond by increasing their production of collagen and elastin and by improving the local environment around them.

That signalling effect is why they are the option most often reached for on thin, delicate or damaged skin — including under the eyes, where a filler frequently makes things worse rather than better.

It will not restore volume. If the problem is a flat midface or a heavy jowl, no amount of regenerative treatment will address it, and a clinic selling you a course for that is selling you the wrong thing.

It will not produce a change anyone else notices in a week. The people who are happiest with this category are the ones who understood the timeline before they started; the people who are disappointed are almost always the ones who were sold it as an event.

And it does not suspend ageing. It improves the condition of the tissue you have, from a baseline that continues to move. Maintenance is part of the treatment rather than an upsell.