Grapefruit seed extract (GSE), also known commercially as Citricidal, was originally developed in 1972 by Dr. Jacob Harich, an immunologist from Germany. dr. Harich became interested in grapefruits when he noticed that they did not decompose as quickly as other fruits. This led him to further research where he discovered that grapefruit seed extract has strong antimicrobial properties.

Originally Dr. Harich used GSE as a water filter and later discovered that it has wide use as an antimicrobial agent. Since then, this product has been commercially sold and used in various forms such as liquid extracts, tablets and creams. Citricidal and other GSE-based products are sold as dietary supplements, antiseptics, and preservatives.