I actually dont know whether that is true about Grapefruit-Seed-Extract being safe. I have stayed well away from the supplement in the past due to reading various reports about it containing a toxic chemical called Triclosan. From what I have read its not the grapefruit seed that has the microbial activity in the supplement but the addition of Triclosan. Triclosan is a toxic chemical used for its antimicrobial properties and is used in many detergents, dishwashing liquids, soaps, deodrants, cosmetics and some toothpastes. Apparantly the safety of Triclosan has been questioned in regard to the risk to human health and the environment. I did also read that in Japan Grapefruit-Seed-Extract has been banned and deemed unfit for human consumption. The nutrition company here in UK that sells Grapefruit-Seed-Extract re-assure me that there is only a small amount of Triclosan in the product and it is harmless but I am not prepared to risk it. I am not saying that is what is causing your reaction - I am just pointing out that maybe GSE is not all its cracked up to be safety wise. Check out this site or just google grapefruit seed extract/triclosan and read the evidence for yourselves. http://www.health-report.co.uk/probiotics-triclosan-dangers.htm
Better safe than sorry I say - after all we all have enough to worry about!