What it is
Hydroxypropyl methylcellulose is a semi-synthetic polymer made by chemically modifying cellulose with hydroxypropyl and methyl groups. In water it forms clear, viscous solutions, which makes it useful for thickening gels and lotions and for stabilizing emulsions. In sunscreens it can also help build a uniform film that supports even product spread.
Safety & warnings
Hydroxypropyl methylcellulose is considered low-irritation and is widely used in cosmetics, foods, and pharmaceuticals. It is not associated with notable allergenicity or comedogenicity at typical use levels.
Origin & sourcing
Semi-synthetic. It is produced from plant-derived cellulose that is etherified with propylene oxide and methyl chloride to introduce hydroxypropyl and methoxy groups.
Questions everyone asks
Is hydroxypropyl methylcellulose the same as hypromellose?
Yes. Hypromellose is the common pharmaceutical name for the same modified cellulose polymer.
Why is it used in sunscreens?
It thickens the formula, helps stabilize emulsions, and can form a smooth film that aids even application.