Rituximab is administered as an intravenous (IV) infusion in a clinic or hospital setting, with each session typically lasting several hours. A subcutaneous (under-the-skin) injection form also exists for certain blood cancers, which takes only about five minutes. The method, dose, and schedule all depend on the condition being treated.
Before the Infusion Starts
Every patient needs screening for hepatitis B before receiving rituximab. Because the drug suppresses a key part of the immune system (B cells), it can reactivate dormant hepatitis B infections, sometimes with serious consequences. Your medical team will check for three specific hepatitis B markers, and if any suggest a current or past infection, you may need antiviral medication to prevent reactivation during treatment.
About 30 minutes before each infusion, you’ll receive premedication to reduce the chance of a reaction. This typically includes a fever reducer, an antihistamine, and sometimes a corticosteroid. These medications help blunt the immune response your body can mount against the drug, especially during the first dose.
How the IV Infusion Works
Rituximab is diluted into an IV bag and infused slowly through a vein, usually in your arm. The infusion rate starts low and is gradually increased if you tolerate it well. This cautious approach exists because infusion reactions are most common and most severe during the first dose. Roughly 80% of fatal infusion reactions have occurred with the first infusion, with serious symptoms typically appearing within 30 to 120 minutes of starting.
For the first infusion, expect to be in the chair for several hours. Your nurse will monitor your vital signs throughout and can slow or pause the infusion if you develop symptoms like hives, drops in blood pressure, shortness of breath, or throat tightness. Subsequent infusions often go faster, since your body has already been exposed to the drug once.
Some cancer centers use a rapid infusion protocol that delivers the drug in about 90 minutes instead of the standard longer infusion. This shortened approach is generally reserved for patients who have already tolerated at least one full infusion within the past 90 days, are receiving a dose of 375 mg per square meter of body surface area or less, and have never had a severe reaction to rituximab. Patients being treated for autoimmune conditions like arthritis or lupus are typically excluded from rapid infusion protocols.
The Subcutaneous Option
A formulation combining rituximab with an enzyme that helps the drug absorb under the skin is approved for certain types of non-Hodgkin’s lymphoma and chronic lymphocytic leukemia. The fixed doses are 1,400 mg for lymphoma and 1,600 mg for leukemia, injected under the skin over approximately five minutes. This is dramatically faster than IV infusion and is generally offered after a patient has already received at least one full IV dose without a significant reaction.
The subcutaneous form is not currently approved for autoimmune conditions like rheumatoid arthritis or vasculitis.
Dosing Schedules by Condition
The dose and frequency of rituximab vary considerably depending on what it’s treating. Here’s how the main schedules break down:
Blood Cancers
For most types of non-Hodgkin’s lymphoma, the standard dose is 375 mg per square meter of body surface area. How often you receive it depends on the specific type and stage. For relapsed or refractory low-grade lymphoma, it’s typically given once a week for four or eight weeks. When combined with chemotherapy for aggressive lymphoma (diffuse large B-cell), it’s given on day one of each chemotherapy cycle for up to eight infusions. As maintenance therapy for follicular lymphoma, it shifts to once every eight weeks for up to 12 doses.
For chronic lymphocytic leukemia, the first dose is 375 mg per square meter, then the dose increases to 500 mg per square meter for cycles two through six, given every 28 days alongside chemotherapy.
Rheumatoid Arthritis
The schedule here is simpler: two infusions of 1,000 mg each, separated by two weeks. That pair of infusions counts as one course. Repeat courses are given roughly every 24 weeks (about six months), though your doctor may adjust the timing based on how you respond. Courses are never repeated sooner than every 16 weeks. Rituximab for RA is always used alongside methotrexate.
Vasculitis (GPA and MPA)
For adults starting treatment, the dose is 375 mg per square meter once weekly for four weeks. After that initial phase, follow-up treatment switches to two 500 mg infusions separated by two weeks, then 500 mg every six months. Pediatric patients follow the same induction schedule but receive lower follow-up doses of 250 mg per square meter.
Pemphigus Vulgaris
Initial treatment mirrors the rheumatoid arthritis approach: two 1,000 mg infusions two weeks apart. Maintenance begins at month 12 with a 500 mg infusion, then every six months after that. If a relapse occurs, a single 1,000 mg infusion is given, with no repeat dose sooner than 16 weeks later.
What Infusion Reactions Feel Like
Infusion-related reactions are the most common side effect, and they range from mild to life-threatening. Mild reactions include chills, fever, and itching. More serious reactions can involve hives, a sudden drop in blood pressure, swelling of the throat or face, difficulty breathing, wheezing, or chest tightness. In rare cases, reactions have included heart complications and severe breathing problems requiring emergency intervention.
Most serious reactions happen during or shortly after the first infusion, but they can occur up to 24 hours later. This is why rituximab is only given in a healthcare setting with staff and equipment ready to manage a severe reaction. You’ll be observed after each infusion before being sent home, and you should have a plan for how to get medical help if symptoms develop after you leave.
Reactions become less common with each subsequent infusion. Many people who had mild symptoms during their first dose experience little or nothing during later treatments.
What to Expect on Infusion Day
Plan for a long visit, especially for your first infusion. Between check-in, premedication, the infusion itself, and the observation period afterward, a first session can take most of a day. Bring something to pass the time. Subsequent visits are shorter, particularly if you qualify for a faster infusion rate or switch to the subcutaneous injection.
You’ll want someone to drive you home after your first infusion, since the premedication can cause drowsiness and there’s a small chance of a delayed reaction. Fatigue in the days following an infusion is common. Some people also experience headaches, mild nausea, or muscle aches that resolve within a day or two.