Centella asiatica (cica) — Korea's "tiger grass"

Centella asiatica is a plant that grows wild in tropical regions of Africa and Asia and on many Pacific islands. Cleveland Clinic says it belongs to the parsley family and has been used in Ayurvedic and traditional Chinese medicine for thousands of years. It goes by many names: cica, tiger grass, Indian pennywort, gotu kola. In Korean it is byeongpul (병풀).

A 2013 review in Advances in Dermatology and Allergology names its active compounds as pentacyclic triterpenes, mainly asiaticoside, madecassoside, asiatic acid and madecassic acid.

Cleveland Clinic says centella is a staple of K-beauty products and that, according to a dermatology physician assistant it interviewed, it helps skin hold moisture and reduces redness and inflammation, which matters for dry or sensitive skin. It also says the science is still fairly preliminary: there are fewer studies than you might expect.

The 2013 review reports that centella extracts have been studied for small wounds, scars and burns, and that results suggest possible uses for photoaging, cellulite and stretch marks. Claims about anti-aging, scars or healing need more research, so treat cica in a cosmetic as a soothing, hydrating helper, not a treatment.

On the label, look for Centella Asiatica Extract (in an ingredient list it is usually written in the English INCI form). Products also use the names cica, centella, madecassoside or tiger grass. Check where it sits in the list: SKIN1004's ampoule has it fourth in a seven-ingredient list, while in Anua's toner it is one extract among many.

A dermatology PA quoted by Cleveland Clinic suggests leave-on products such as creams, serums and lotions, which stay on the face longer than rinse-off ones. Toners, ampoules and sunscreens also carry it.

Cleveland Clinic says centella is safe for most people, but a rare allergy is possible; the most common reactions are a burning feeling or contact dermatitis. Spot-test on your inner arm and wait at least 24 hours. It also says to ask a dermatology provider first if you are under 18, pregnant or breastfeeding, or have a history of liver problems or skin cancer.

The AAD's patch test is stricter: a quarter-sized spot, twice a day, for seven to 10 days.