Chlorophyll is not to be considered a poison by the U.S National Library of Medicine (NLM), is always good news, and is not likely to have any side effects or cause any symptoms that will harm you in any way.
There are, however, a few side effects to watch for, while not necessarily harmful, can be irritating.
Diarrhea - It is rare to develop diarrhea when taking chlorophyll, but it is not unheard of. If you have loose stools for longer than a few days, it is time to call your doctor.
Stomach cramps - Stomach cramps are not necessarily dangerous, but they can certainly make you uncomfortable. The stomach cramps may come with diarrhea, and if they do not go away within a few days, you need to contact your doctor.
Discolorations of the tongue, urine, and stool - While this is an odd side effect to have happen to you, it is harmless. With that said, just a heads up that consuming chlorophyll can result in color changes to your urine and stool, giving them a more greenish hue. It can also change your tongue from yellow to black.
Burning or itching of the skin -Some people use chlorophyll topically to help with wound healing. When chlorophyll comes into contact with the skin, it can cause a mild burning sensation or itching. While not harmful, it can be very unpleasant to deal with this possible side effect.