As we learn more about ingredients and skincare terms, there is now a broader focus on these ingredients' percentages. We have begun to see problematic ratios starting to confuse consumers. Logically many start thinking that a 20 percent vitamin C serum is more potent and superior to one of 10 percent, but that's not always the case. More of an active ingredient doesn't necessarily mean better.
We did a deep dive into the actual studies done on the ingredients and what percentage they seem to be active yet safe enough not to risk an irritation. However, things are not always black and white when it comes to science.
Formulations containing between 3 percent and 5 percent hit the sweet spot for everyday use. PH should be of 3-4. A 5 percent glycolic with a high pH level weakens the acid, lowering it to around 2 percent.
Studies have shown that 5% have proven to be effective on blemishes and brightening skin tone. When using a high percentage of up 10% - 20%, some start seeing irritations.
L-ascorbic acid is the most potent form. However, it is also precarious with incorrect packaging. A stable 5 percent vitamin C serum will be more effective than a 25 percent serum that isn't stable. Also, note that not all Vitamin C's are actual L-ascorbic acid.
As there are so many variations of Vitamin A, it all depends on the form used. For example, A 10% percent retinyl palmitate serum is weaker than a 5 percent retinol serum.
Retinoic acid is the strongest; it is a prescription-only. Retinol (two conversation steps) is weaker and less irritating. Finally, retinyl palmitate is most gentle, yet it also cannot guarantee results as it's three conversion steps to retinoic acid.
Mandelic Acid: Studies show that going above 10% may be counterproductive
You can move on to a higher percentage of actives once your tolerance levels adjust; usually, it is months of use, not weeks.