In cosmetics, the best active ingredients for adding volume to fine or flat hair are essentially those capable of increasing the diameter of the hair fibre. However, they do not actually affect the biology of the follicle. They simply create the illusion of thicker hair, which may be enough to give the appearance of fuller hair on a day-to-day basis. In this category, the main ingredients are plant-based powders and film-forming agents, particularly proteins (keratin, collagen, silk), which form a thickening coating around the hair. We should also mention moisturising active ingredients, which create volume through water-induced swelling.
Visual volume also comes from the roots. In this case, just like the previous category of volumising active ingredients, it has the advantage of being immediately visible. Certain active ingredients help to lift the roots slightly: a temporary effect that gives the hair a denser appearance. In the same vein, active ingredients that target the balance of the scalp are highly relevant to complement a volumising strategy, particularly in cases of hair loss or thinning hair.
There are other interesting active ingredients which, in this case, can claim to have a stimulating effect on the hair follicle. Very few have a direct effect on hair thickness, although some can be found in a few topical scalp serums. Most actually have an indirect effect, for example by increasing the number of hairs in the anagen phase (growth phase). This phase of the hair cycle corresponds to the stage where growth strictly speaking; it can have an indirect volumising effect if properly targeted.
In addition to topically applied active ingredients, certain dietary supplements are also relevant. Research tends, however, to show that they have only a limited impact on hair volume when used on their own (1). It would therefore be preferable to take them as a supportive measure, particularly in cases of an initial imbalance; otherwise, their effects remain modest.
