Since I use the ampoules in parallel with the corresponding foam, I will also add my evaluation here.
I have been using Vichy Dercos Aminexil products (initially the ampoules and in the last few years the foam as well) for about a decade now, ever since I first noticed thinning at the top of my head, which fortunately stopped when I started the treatments. Since then, I have been using them regularly but with some breaks, in combination with the corresponding shampoo, "Vichy Dercos Energising Shampoo Anti-Hair Loss" (I have only been using this shampoo for a decade).
I must mention that acquaintances of mine who had a major thinning problem and used the same products did not have significant results in the end. So, I understood that they are only suitable for addressing the problem at its beginning. According to my own experience, a slight thinning at the beginning is effectively treated and the hair gradually thickens. Therefore, if someone notices thinning at the start, they should not wait but start the treatment immediately.
Of course, this treatment is not a one-time thing. It needs to be repeated at regular intervals. I noticed that when I stopped for a long period, the thinning would reappear.
So, if we are talking about cases that are still at the beginning of the problem, the product does what it promises: it strengthens, resulting in less hair loss and thicker hair. When I first used the ampoules, it took three treatments (about three months) to see the first positive results. It requires some patience.
Also, the ampoules are stronger than the foam. The foam works more for maintenance. So, if we realize at some point that it is not effective, then we should use the ampoules again for one or two months and then switch back. As I mentioned before, the result is not permanent, it requires maintenance.