Tysabri Injection stops the cells that cause inflammation from going into your brain. This reduces nerve damage caused by MS. This medicine often causes nausea and vomiting. However, it is important that you continue to receive the medicine, even if you begin to feel ill. Do not stop taking this medicine without first checking with your doctor. Inform your doctor if you develop symptoms like abdominal pain, loss of appetite, darkened urine or yellowing of the eyes or skin. These may be the signs liver damage.