Rituximab and Abatacept: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 16, 2026 · Source data updated Jul 16, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Abatacept
Rituximab
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Both abatacept (Orencia) and rituximab are biologic medicines that calm down parts of your immune system to treat conditions like rheumatoid arthritis. The concern with taking them together is simple: when you dial down two different parts of the immune system at once, your body has a harder time fighting off germs. That means a higher chance of getting a serious infection, without clear extra benefit for your arthritis.
This is mostly a caution based on how these drugs work and on studies of similar drug combinations, not a proven danger for this exact pair. Please don't stop or change anything on your own. Your care team can look at your treatment plan and pick the safest option for you.
Effect: Additive immunosuppression increasing the risk of serious infection when abatacept is combined with another biologic DMARD such as rituximab, with no proven added efficacy.
- Mechanism: Unknown/unspecified; presumed additive suppression of immune function (neither agent is bioactivated, so effect is pharmacodynamic, not metabolic).
- Direction: Increased infection risk (additive PD effect).
- Evidence: Theoretical for this pair; extrapolated from controlled trials of abatacept plus TNF antagonists.
- Severity/Onset: Major; onset unspecified.
- Management: Concurrent use of abatacept with other RA/PsA biologics is not recommended. If transitioning, monitor closely for signs of infection.
What happens
An increased risk of infection
Interaction Deep Dive
In controlled clinical studies, combining abatacept with tumor necrosis factor (TNF) antagonists was shown to raise the risk of serious infection without delivering any extra therapeutic benefit. Data are inadequate to determine how safe and effective abatacept is when given together with anakinra or with biologic agents used for rheumatoid arthritis or psoriatic arthritis. For this reason, using these agents at the same time is not advised. Patients being switched from TNF antagonist treatment to abatacept should be watched for indications of infection1.
Why it happens (mechanism)
Unknown
How to manage this interaction
The general guidance is that abatacept and rituximab are not recommended to be used together, because combining two biologics raises infection risk without added benefit.
- Keep taking your medications as prescribed and do not stop either one on your own.
- Talk with your rheumatologist or pharmacist so your team can review your regimen and, if needed, choose one biologic rather than both.
- If your care team is switching you from one to the other, expect them to watch you closely for signs of infection (fever, chills, cough, sores that won't heal).
- Report any infection symptoms promptly.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Taking abatacept together with etanercept provided no additional benefit but raised the risk of serious infection when compared with etanercept used by itself. In a 1-year, randomized study (N=121) that was followed by an open-label long-term extension (LTE; n=80), rheumatoid arthritis patients who were already receiving etanercept 25 mg twice/week kept taking etanercept and were randomized to receive either abatacept 2 mg/kg IV on days 1, 15, and 30, and then every 4 weeks (n=85) or placebo (n=36). After the double-blind phase ended, patients could enter the LTE phase, during which the abatacept dose was raised to roughly 10 mg/kg. At 6 months, the 2 mg/kg abatacept group did not show a significant improvement over the placebo group in modified American College of Rheumatology 20% (ACR20; 48.2% vs 30.6%) or ACR50 (25.9% vs 19.4%) response rates, though there was a significant difference in modified ACR70 rates (10.6% vs 0%). At 1 year, no significant differences in ACR20, 50, or 70 response rates were seen between the two groups. Serious adverse events occurred more often in the 2 mg/kg abatacept group (16.5%) at one year and in the 10 mg/kg abatacept group after 2 years of LTE (32.5%) than in the placebo group (2.8%). Serious infections at 1 year were reported in 3.5% of the 2 mg/kg abatacept group and 0% of the placebo group 2.
b) In controlled clinical trials involving adults with active rheumatoid arthritis who received abatacept together with a tumor necrosis factor (TNF) antagonist (n=204), compared with those on TNF antagonist therapy alone (n=134), the rate of infection (63% vs 43%, respectively) and of serious infection (4.4% vs 0.8%, respectively) was higher with the combined therapy; furthermore, the combined therapy offered no additional benefit 1.
Common questions
Can I take Rituximab and Abatacept together?
Using abatacept and rituximab together is generally not recommended because it can raise the risk of serious infection without extra benefit; talk with your rheumatologist about using one biologic and watch for signs of infection. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Rituximab and Abatacept interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Rituximab and Abatacept interaction managed?
The general guidance is that abatacept and rituximab are not recommended to be used together, because combining two biologics raises infection risk without added benefit. Keep taking your medications as prescribed and do not stop either one on your own. Talk with your rheumatologist or pharmacist so your team can review your regimen and, if needed, choose one biologic rather than both. If your car… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Rituximab or Abatacept need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: ORENCIA(R) intravenous, subcutaneous injection, abatacept intravenous, subcutaneous injection. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2020. DailyMed
- Weinblatt M, Schiff M, Goldman A, et al: Selective costimulation modulation using abatacept in patients with active rheumatoid arthritis while receiving etanercept: a randomised clinical trial. Ann Rheum Dis 2007; 66(2):228-234. PubMed
Keep reading about Abatacept
Keep reading about Rituximab
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