Ingredient lists display all ingredients in descending order of concentration. In other words, the ingredients listed first are the main components of that serum.
The First Three Are Base Ingredients
In most serums, the first three ingredients are base components such as "Water, BG, Glycerin." These form the product's foundation and are common across virtually all brands. What matters is what comes fourth and beyond. This is where the brand's "star" active ingredients appear.
Understanding the "1% Line"
There is another concept worth remembering: the "1% Line."
When you spot "Phenoxyethanol" -- a preservative -- in the ingredient list, it signals that ingredients listed from that point onward are present at 1% or less. This is because regulations cap this preservative at a maximum of 1%.
In other words, ingredients listed before Phenoxyethanol are likely at 1% or above, while those listed after it are likely below 1%.
The Reality Behind "Contains"
Even when "Contains Hyaluronic Acid!" or "Contains Retinol!" is prominently displayed, if the ingredient appears after the 1% line, it may be present in only trace amounts.
The next consideration is not just "what is in it" but "how much is in it" -- the question of concentration.
References
Key peer-reviewed sources behind the scientific statements in this article.
- Kafi R, Kwak HS, Schumacher WE, Cho S, Hanft VN, Hamilton TA, King AL, Neal JD, Varani J, Fisher GJ, Voorhees JJ, Kang S. Improvement of naturally aged skin with vitamin A (retinol). Arch Dermatol. 2007;143(5):606-612. PubMed
- Mukherjee S, Date A, Patravale V, Korting HC, Roeder A, Weindl G. Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety. Clin Interv Aging. 2006;1(4):327-348. PubMed