What is it?
Sea water extract is an extract of sea water, also called maris aqua extract. Sea water carries many dissolved minerals, including sodium, magnesium, potassium, calcium, chlorides and sulfates. The EU lists sea water extract as a skin-conditioning ingredient, one added to help keep skin in good condition. The ingredient name does not say where the water was collected or how it was processed.
Key information
- Sea water extract is an extract of sea water, a source of minerals such as sodium, magnesium, potassium and calcium.
- It has not been reviewed by CIR or the EU's SCCS, and the EU places no restrictions on it.
- Sea water can contain naturally occurring toxic metals such as cadmium and lead, so its purity must be controlled.
More information
The EU’s cosmetic ingredient database, CosIng, defines sea water extract simply as “the extract of Sea Water,” with no details on source or method, and lists no restrictions or safety opinion. A 2023 review of marine cosmetic ingredients describes sea water as an abundant source of minerals used in skin care, including potassium, magnesium, sulfates, sodium, calcium and chlorides. It also notes interest in deep-sea water, which is thought to have an even higher mineral content than average sea water.
Neither the Cosmetic Ingredient Review (CIR) nor the EU’s Scientific Committee on Consumer Safety has assessed sea water extract, and we found no reports of harm from its use in cosmetics. Studies of seawater applied to skin in a therapeutic setting report few problems: a 2025 systematic review of seawater and mineral-water therapies for people with eczema (atopic dermatitis) found that side effects were minimal and mild, such as stinging on first contact with seawater, although its authors called for larger, standardized trials.
The main question for any marine ingredient is purity. The 2023 review warns that sea water and sea mud may contain naturally occurring toxic metals, such as cadmium and lead, and says strict control is needed before they go into cosmetics. It adds that marine-derived ingredients should be checked for arsenic and mercury, as well as for toxins and allergens. On labels, look for sea water extract or maris aqua extract; the label will not tell you where the water came from.
Sources: European Commission CosIng: Sea Water Extract; Marine Drugs (2023): Marine natural products as innovative cosmetic ingredients; Cureus (2025): Efficacy and safety of seawater therapy versus non-pharmacological interventions for atopic dermatitis: a systematic review
