Dangers of Rituxan Rituxan has not been as successful in treating cancer as drug companies would like you to believe. In fact personal injury lawyers have websites all over the internet issuing warnings about the dangers of Rituxan and offering to file a law suit on your behalf if you have used this dangerous drug. Below are several documents and research studies on the dangers and problems of Rituxan. Rituxan suppresses the body's ability to produce certain types of white blood cells called B cells for periods between six and nine months. Unfortunately, a side effect of suppressing the immune system is that it decreases the body's natural disease and infection fighting capabilities, leaving the patient open to a host of serious complications such as PML (PML is an extremely dangerous and usually fatal disease that affects the central nervous system and the brain).