Stinging nettle is associated with only occasional, mild side effects such as rash, fluid retention and upset stomach.For more information about men???s health and prostate health, see prostate.net.Sources:[1] University of Maryland: <a href="http://www.umm.edu/altmed/articles/stinging-nettle-000275.htm[2]">http://www.umm.edu/altmed/articles/stinging-nettle-000275.htm[2]</a> Urtica dioica for treatment of benign prostatic hyperplasia: a prospective, randomized, double-blind,