The Working Range Is 5 to 15 Percent
In leave-on products, 5 to 15 percent is the concentration range recognised as safe by the FDA and EFSA. Irritation potential at those levels is low and allergic reactions are rare, with an incidence below 1 percent.
Above 70 Percent in Dry Air Glycerin Works Backwards
In low-humidity environments below 40 percent relative humidity, concentrations above 70 percent can cause reverse hydration, extracting moisture from the skin and leading to dryness or irritation. If you export to dry markets, this is a formulation decision, not a theoretical risk.
Pair It Rather Than Push It
Combining glycerin with occlusives such as petrolatum, or polysaccharides such as glucan, prevents moisture loss in dry climates far more effectively than raising the glycerin level.
Grade Decides Whether It Belongs in Cosmetics At All
Use USP pharmaceutical grade at 99.5 percent purity or above, with heavy metals at 1 ppm or less and microbial control complying with USP and EP standards. Industrial-grade glycerin may contain methanol or heavy metals and has no place in a cosmetic or oral care line.
Two Practical Adjustments
For acne-prone targets, hold viscosity at 2,000 cP or less at 25 degrees Celsius to minimise comedogenicity. To protect the system itself, add 0.1 percent ethylhexylglycerin, which improves photostability and reduces degradation by 74 percent.
Every figure quoted here comes from the documentation of the products we supply. Confirm each limit against the regulation in force in your destination market before it enters a specification.
