Xeljanz vs Olumiant
Both are JAK inhibitors. Here is how Xeljanz and Olumiant compare on class, mechanism, dosing, approval and supply.
At a glance
Key differences
- Same class. Both Xeljanz and Olumiant are JAK inhibitors, so they work through the same broad mechanism. Differences between them tend to be about dosing, route, how selective they are, and side effects rather than what they target.
- Time on the market. Xeljanz was first approved by the FDA in 2012, Olumiant in 2018. That gives Xeljanz roughly 6 more years of real-world use and long-term safety data.
- Who markets them. Xeljanz is marketed by Pfizer; Olumiant by Eli Lilly.
What each one treats
XELJANZ (tablets and oral solution) and XELJANZ XR (extended-release tablets) are Janus kinase (JAK) inhibitors. XELJANZ tablets and XELJANZ XR are indicated for the treatment of adult patients with: • Moderately to severely active rheumatoid arthritis (RA), who have had an inadequate response or intolerance to one or more TNF blockers. • Active psoriatic arthritis (PsA), who have had an inadequate response or intolerance to one or more TNF blockers. • Active ankylosing spondylitis (AS), who have had an inadequate response or intolerance to one or more TNF blockers. • Moderately to severely active ulcerative colitis (UC), who have had an inadequate response or intolerance to one or more TNF blockers. XELJANZ (tablets and oral solution) are indicated for the treatment of pediatric patients 2 years of age and older with: • Active PsA, who have had an inadequate response or intolerance to …
An oral daily medication used to treat rheumatoid arthritis, alopecia areata, and severe COVID-19.
How each one works
12.1 Mechanism of Action Tofacitinib is a Janus kinase (JAK) inhibitor. JAKs are intracellular enzymes which transmit signals arising from cytokine or growth factor-receptor interactions on the cellular membrane to influence cellular processes of hematopoiesis and immune cell function. Within the signaling pathway, JAKs phosphorylate and activate Signal Transducers and Activators of Transcription (STATs) which modulate intracellular activity including gene expression. Tofacitinib modulates the signaling pathway at the point of JAKs, preventing the phosphorylation and activation of STATs. JAK enzymes transmit cytokine signaling through pairing of JAKs (e.g., JAK1/JAK3, JAK1/JAK2, JAK1/TyK2, …
An oral daily medication used to treat rheumatoid arthritis, alopecia areata, and severe COVID-19.
Related comparisons
Read more
Which medicine is right for a given person depends on their diagnosis, other conditions, other medicines, kidney and liver function, pregnancy, and cost or reimbursement — none of which this page knows. Two drugs in the same class are not automatically interchangeable. Never start, stop or switch a prescription medicine on the basis of a web page; that decision belongs to you and your clinician or pharmacist.
How this page is built
The facts on this page are pulled directly from official U.S. FDA datasets — they are not written from memory. Each field below names the dataset it came from, so you can check it yourself.
- FDA Drug Label (openFDA) ↗ Indications, mechanism of action and pharmacologic class
- Drugs@FDA ↗ First FDA approval date and the company holding the application
- FDA Drug Shortage Database ↗ Current US supply / shortage status
Plain-English summaries and drug-class explainers are written and reviewed by Sreepriya Prasannan (MSc Digital Transformation of Life Sciences (Innopharma Education / Griffith College); MSc & BSc Botany). Data is retrieved automatically from the sources above and cross-checked with AI-assisted verification (Anthropic's Claude) — brand and generic names are matched against the exact FDA product record so that a combination product or a different formulation cannot be mistaken for the drug on this page. An editor reviews the result before publication. We describe this in full in our editorial standards and corrections policy. The FDA data on this page was last retrieved on 9 Oct 2026. How every register is built: methodology · fixes we have made: corrections log.