What are the possible side effects of Essiac?
The safety of Essiac® is not well studied scientifically. Safety concerns are based on theoretical and known reactions associated with herbal components of Essiac®: burdock root (Arctium lappa), sheep sorrel (Rumex acetosella), slippery elm bark (Ulmus fulva), and Turkish rhubarb (Rheum palmatum). However, the safety and toxicities of these individual herbs are also not well studied. Various Essiac-like products may contain different or additional ingredients, and patients are advised to carefully review product labels. Potentially toxic compounds present in Essiac® include tannins, oxalic acid, and anthraquinones. Tannins, present in burdock, sorrel, rhubarb, and slippery elm, may cause stomach upset, and in high concentrations may lead to kidney or liver damage. In theory, long-term use of tannins may increase the risk of head and neck cancers, although there are no documented human cases. Oxalic acid contained in rhubarb, slippery elm, and sorrel, can cause serious adverse effects w
