No. During our own trials on animals as well as extensive studies and use with humans, the only reported side-effects from using GcMAF have been mild detox-like symptoms. These may include a runny nose, general fatigue, sleeping issues, irritability and mild muscle soreness in the first few days. This is simply the animal’s immune system responding to the initial influx of GcMAF which stimulates detoxification. These symptoms usually subside with 3-4 days, and you may wish to halve the daily dose based on your animal’s size during this period to help minimise any discomfort if applicable. If symptoms persist or you are concerned about anything else, please seek the advice of a veterinarian.