Apart from the tablet being of poor quality, the side effects of chlorine are pervasive if the ratio of usage is incorrect or someone who has a weak immune system comes in contact. However, there are other ways to sanitise without using chlorine. Most of the times, the best thing to do is to hire a professional cleaner and let them do their job, without using chlorine. It's expensive for sure, but worth it. Throat pain, stomach pain, vomiting, blood in the stools, burning in the mouth, swelling or the throat, skin damage and change in blood pressure levels can be some side effects of chlorine.