The best way to reduce the risk of an allergic reaction - to make a product hypoallergenic - is to omit allergens (ingredients that are proven to cause reactions).
In 1988, VMV's founding dermatologist-dermatopathologist (a specialist in contact dermatitis and skin diseases) created the VH-Number Rating System as a standardized, objective measure of allergen omission.
The VH-Number Rating System shows how many allergens have been omitted from a product using independent, objective references: The North American Contact Dermatitis Group (NACDG) and European Surveillance System on Contact Allergies (ESSCA). These highly specialized groups examine the results of thousands of patch tests to determine which ingredients/allergens are causing the most reactions. If an ingredient makes it to one of these lists, we don't use it. It's that simple.
Memorizing the list of allergens is impractical so the VH-Rating is arguably the simplest, most immediate, visible and reliable measure of hypoallergenicity.
If you have had a patch test, the VH-Rating System tells you if there are allergens present, and if so, which ones. For example, if you are interested in a product and see that its rating is VH -75/76*, you know it contains one common allergen. Find the asterisk on the ingredients list and you'll find which ingredient is the allergen. If your patch test shows that you're sensitive to that ingredient, do not use the product. If your patch test does not show the highlighted ingredient, then you should still be able to use the product.
If you haven't yet had a patch test but have a history of skin sensitivity, choose products with the highest VH-Rating.