There are no side effect with this all-natural product. However, for people with too much toxins in their organs, they might experience headache or dizziness for hours, days, or even up to 2 weeks. When toxins are leaving your organs, it doesn't just go directly to your bladder and out of your body. It goes through your bloodstreams then to your bladder. While it is in your bloodstreams, you may have dizziness or headaches, just drink lots of water to help your body quickly get rid of the unwanted stuffs. If dizziness, headaches, or other reactions persist, just reduce the amount to 1/3~1/2 oz per day for a while. Others might have a little diarrhea for a few days, especially for people who already suffer from constipation. It is trying to soften what's already in your intestine for a long time. Constipation is the beginning of accumulation of toxins; DB Nopal Extract Juice will take care of this very quickly. Diarrhea may last from days to 2 weeks, just don't take it in the morning if you experience this, 15 minutes before dinner would be ideal. Another reason why you are having diarrhea is because your digestive system environment is very acidic. Acidity produces inflammation and inflammation leads to many diseases. However, by changing the PH level too fast may create diarrhea. The only way to deal with it is to change the PH level slowly.  Take only 1/3 ~ 1/2 oz a day instead of 1 oz a day in the beginning.  As your digestive system becomes more alkalized, then, you can do 1 oz a day. On the other hand, 5% of people might experience constipation. It is called "complex constipation". Please drink twice instead of once a day for 2 weeks and add yogurt or other sources of probiotic to mix with nopal juice extract.