5.5 Rituxan Rituximab is a chimeric monoclonal antibody used in the treatment of B cell non-Hodgkin's lymphoma, B cell leukemia, and numerous autoimmune disorders. The recommended adult dosage for patients with low grade or follicular NHL is 375 mg/m2 infused intravenously and for adult patients with autoimmune diseases a standard 500 mg is generally given intravenously. The infusion may be given at weekly intervals for four total dosages or once every 2 weeks and repeated 2-3 times. Acetaminophen and diphenhydramine hydrochoride are given 30-60 minutes before the infusion to help reduce side effects. If given as a retreatment the dosage is the same. The majority of side effects occur after or during the first infusion of the drug. Some common side effects include dizziness, feeling of swelling of tongue or throat, fever and chills, flushing of face, headache, itching, nausea and vomiting, runny nose, shortness of breath, skin rash, and fatigue.