There are no known side effects. Fulvic and Humic Acid is a nutritional supplement and as such unused portions are naturally flushed from the body when not required or too much has been ingested. You cannot overdose on Fulvic Acid. There are however side effects if you take FulvicExcel and you are sulfur intolerant or allergic to seafood. Be sure to check on the precautions before ordering.