Four categories — filling, provoking, muscle, form

This page is written for general readers. It does not recommend any procedure, product or clinic, and it carries no efficacy, duration or price information. Decisions about treatment belong with a qualified clinician who has examined you.

Question

What is the difference between skin boosters, fillers, botulinum toxin and threads?

These four are discussed as if they were one menu, but what they do in the body differs. One occupies space, one provokes the body into building something, one reduces the signal running to a muscle, and one holds tissue in a new position. Sorting them by what they do rather than by product name means that an unfamiliar name can still be placed correctly.

Sort by what it does, not by its name

Product names in this field keep multiplying. Following the names has no end, but what these things do in the body narrows to a few options. Once you can place an unfamiliar name in one of them, the rest follows.

The ones that fill

The material placed occupies that space. Hyaluronic acid fillers belong here. Hyaluronan is already present in skin; crosslinking it chemically into a gel makes it resist breakdown and hold its shape.

One thing in this category is worth noting. The literature records an enzyme that degrades this gel. For most other materials this site covers, no such means is recorded.

The ones that provoke the body to build

Here the material does not occupy the space itself. Instead the body responds to it and builds something. Poly-L-lactic acid and calcium hydroxylapatite belong here, and they are commonly grouped under the name “collagen boosters”.

In this category the result comes from the body’s response rather than from the amount placed, which leaves more room for variation between people than the filling side. How to read claims in this category is covered on a separate page.

The one that acts on muscle

Botulinum toxin is neither of the above. It does nothing in the dermis; it reduces the signal running from nerve to muscle. With less movement, the lines that movement was folding become less pronounced.

This material differs from the others in its regulatory kind. In the two markets where classification could be established, it is a medicine rather than a device. That also changes the range of what may be said about it in public.

The one with a different form

By material, threads are often the same family of polymer as the “provoking” side above. What differs is form. Instead of being dispersed as particles, the material is laid along a plane as a single strand and anchored.

So threads carry questions the others do not: whether the anchoring holds, whether it can be felt, whether it shows. Conversely, those questions do not arise for an injected suspension.

When you meet a name you have not heard

Start by asking what material it is. The material usually settles which of the four boxes it belongs in, and the questions that follow come with it.

What to check first

Does this fill, or does it provoke the body to build?

Most of the field divides on this one question. What fills occupies the space it was placed in; what provokes produces a response from the body, which leaves more room for variation between people.
What material is it?

A product name is chosen by a company; a material name is not. Knowing the material lets you recognise the same thing sold under a different name, and lets you check it against references organised by material, as this site is.
Can it be reversed?

Some materials have a means of removal and some do not. The literature records an enzyme that degrades crosslinked hyaluronic acid; for most other materials on this site no corresponding agent is recorded. This question comes before duration, not after it.
What layer is it placed in?

The same material raises different questions depending on the depth it is placed at. Something applied to the surface and something placed in the dermis differ from the regulatory classification onward.

What this page does not say

This page explains only what each of the four categories does. It does not address which category suits which person; that judgement belongs with a clinician who has examined you. The distinctions here concern the mode of action described in the literature, not how much effect appears or how long it lasts. Some products span two categories, so these four boxes are not an exhaustive classification.