How to take Rituxan. Rituxan is injected into a vein through an IV. A healthcare provider will give you this injection. Rituxan is not given daily. Your schedule will depend on the condition being treated. Follow your doctor’s dosing instructions very carefully. Your doctor will perform blood tests to make sure you do not have conditions that would prevent you from safely using Rituxan. Before each injection, you may be given other medications to prevent certain side effects of Rituxan.