What it is
Algin is the salt form of alginic acid, a natural polysaccharide extracted from brown algae. In cosmetics it is used to thicken formulas, stabilize emulsions, and form a light film on the skin surface, which can improve texture and spreadability. In sunscreens it supports the formula structure rather than providing UV protection.
Safety & warnings
Algin is widely used and generally well tolerated in topical products. It is not a recognized fragrance allergen and is not an oil, so comedogenicity is not a typical concern.
Origin & sourcing
Natural, extracted from brown seaweed (brown algae), commonly as the sodium salt of alginic acid.
History
Alginates have a long history of use as thickening and gelling agents in food and personal care products, derived from seaweed harvesting and processing.
Questions everyone asks
Where does algin come from?
It is extracted from brown seaweed and is the salt form of alginic acid, a natural polysaccharide.
What is its role in a sunscreen?
It thickens and stabilizes the formula and can help form a smooth film, improving texture; it does not contribute UV protection.