A general name for a variety of aquatic algae. Seaweed is sometimes used in lubricants, massage liquids, and cosmetics for its apparent skin-friendly qualities.

Red algae (carrageenan) and brown algae (Phaeophyceae) may have anti-inflammatory properties, and both contain fairly significant amounts of antioxidants. This may promote immune system function. Products with seaweed can soften and moisturize the skin; seaweed wraps are a popular option at spas for this reason.

While side effects can vary depending on the algae species and preparation, seaweed skin products are generally very safe, especially when prepared with natural sources.

See “carrageenan” for more information on red algae.