Reported side effects are generally mild and include temporary gastrointestinal discomfort, headaches during initial use, occasional fatigue as the body adjusts, and rare nausea, especially when taken without food
KLOW is a much more recent discovery in the peptide world, so the body of peer-reviewed research is naturally smaller but is growing rapidly as of 2026
J Food Nutr Res 51:109112 Wang K, Guo J, Cheng J, Zhao X, Ma B, Yang X, Shao H (2021a) Ultrasound-assisted extraction of polysaccharide from spent Lentinus edodes substrate: process optimization, precipitation, structural characterization and antioxidant activity
Glutathione Side Effects: What You Need to Know Despite its numerous benefits, glutathione can have unexpected side effects if taken in too high doses or if it interacts with certain medications