Lithothamnion Calcareum Extract

Lithothamnion calcareum extract (red algae/calcified seaweed) is typically used at low concentrations as a mineral-rich soothing/conditioning agent (source of calcium/magnesium carbonates) rather than a potent active. Patch-test and clinical use trends suggest low inherent irritation, but as a marine botanical/extract it can still trigger reactivity or contact dermatitis in highly sensitized eczema-prone patients, and its alkalinity/mineral particulates can be mildly destabilizing in already-impaired barriers. Given this non-zero but generally low risk, it fits best as a gentle ingredient with minimal irritation potential. Safety Notes: Lithothamnion calcareum extract (a calcified red algae/mineralizing algae extract) is commonly used as a minor “marine/mineral” skin-conditioning component in leave-on creams/serums and masks at very low levels (often around 0.001–0.1%), especially when supplied as a diluted/glycerin or water-based extract. Higher levels are seen in consumer-available “marine mineral/algue” and body-firming products, bath/soak, and some mask/gel formats where the extract (or concentrated extract blend) is used more assertively, reaching ~1–5% without being prescription-only; above this, texture/whiteness/mineral load and raw material format typically become limiting. Usage is broadly similar across leave-on and rinse-off, but rinse-off/mask products more often sit at the upper end due to easier sensory tolerance.