Ruxolitinib
Pronunciation: rux-oh-LIT-i-nib.
- Generic name
- ruxolitinib
- Drug class
- JAK1/JAK2 (Janus kinase) inhibitor
- Form
- Tablet (5 mg, 10 mg, 15 mg, 20 mg, 25 mg); extended-release tablet (11 mg, 22 mg, 33 mg, 44 mg, 55 mg, US only); oral solution (5 mg/mL, UK)
- Route
- Oral
- Legal status
- Prescription-only, specialist-initiated (haematology/oncology)
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand
Australia: Jakavi (5) · Full directory
What ruxolitinib is and how it works
Ruxolitinib is a prescription-only JAK1/JAK2 inhibitor used to treat certain blood and bone-marrow disorders and graft-versus-host disease. It is initiated and monitored by a haematology or oncology specialist, not a self-selected or self-adjusted medicine. (1) (2)
Take ruxolitinib exactly as your specialist prescribes. Do not change your dose or stop taking it without talking to your prescriber first -- stopping suddenly can cause a serious flare of your underlying condition. Your care team will check your blood counts and other tests regularly while you are on treatment.
Mechanism of action: how ruxolitinib works
Ruxolitinib is a selective inhibitor of Janus kinase 1 and 2 (JAK1/JAK2), enzymes involved in signalling pathways relevant to myeloproliferative disease and immune-mediated processes such as graft-versus-host disease. (1) (2)
What ruxolitinib is used for
Myelofibrosis
Approved for intermediate- or high-risk myelofibrosis in adults, including primary myelofibrosis, post-polycythemia-vera myelofibrosis, and post-essential-thrombocythemia myelofibrosis (US); disease-related splenomegaly or symptoms in these same groups (UK/EU/Australia/New Zealand). (1) (2) (5) (6)
Polycythemia vera
Approved for adults with polycythemia vera who have had an inadequate response to, or are intolerant of, hydroxyurea. (1) (3)
Graft-versus-host disease (GVHD)
Approved for steroid-refractory acute GVHD (adults and, in the US, pediatric patients 12 years and older; UK/EU from age 2) with inadequate response to corticosteroids, and for chronic GVHD after failure of one or two prior lines of systemic therapy. (1) (2) (3)
Before taking ruxolitinib
Do not take / not appropriate for
- There are no contraindications listed in the US prescribing information. (United States) (1)
Tell your clinician about
- Any current infection, or a history of tuberculosis, hepatitis B, or recurrent herpes simplex/zoster (shingles) -- ruxolitinib can allow serious infections to develop or reactivate.
- Any heart problems, blood clots (DVT/PE), smoking history, or other cardiovascular risk factors.
- Any personal or family history of cancer.
- Liver or kidney problems -- your dose may need to be reduced.
- High cholesterol or triglycerides.
- All other medicines, especially fluconazole or other antifungal medicines, and any medicine described as a 'strong CYP3A4 inhibitor or inducer' -- these can require a dose change.
- Pregnancy, plans for pregnancy, or breastfeeding.
How to take ruxolitinib
- Take ruxolitinib exactly as your specialist prescribes -- your exact dose depends on which condition is being treated and, for myelofibrosis, your platelet count.
- JAKAFI (immediate-release) tablets are taken twice daily; JAKAFI XR (extended-release, US only) is taken once daily -- do not switch between the two without your prescriber's direction, as they are dosed differently.
- Your specialist will check your blood counts regularly (approximately every 2-4 weeks when starting) and may adjust your dose based on the results.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)
Missed dose
This is a specialist-monitored medicine with dosing that depends on your blood test results. If you miss a dose, contact your specialist team for guidance rather than adjusting the dose yourself.
Overdose
Seek urgent medical attention or contact your specialist team immediately if too much ruxolitinib has been taken. (1)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms.
Low platelet count and low red blood cell count (anaemia) are very common in myelofibrosis and polycythemia vera treatment.
What to notice: Low platelet count and low red blood cell count (anaemia) are very common in myelofibrosis and polycythemia vera treatment.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)
Bruising, dizziness, headache, and diarrhoea.
What to notice: Bruising, dizziness, headache, and diarrhoea.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)
In graft-versus-host disease treatment: low blood counts (anaemia, low platelets, low neutrophils), infections, and swelling (oedema) are very common.
What to notice: In graft-versus-host disease treatment: low blood counts (anaemia, low platelets, low neutrophils), infections, and swelling (oedema) are very common.
What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)
Serious warnings
Serious bacterial, mycobacterial (including tuberculosis), fungal, and viral infections have occurred, including reactivation of hepatitis B and herpes simplex/zoster (shingles) — serious
Symptoms: Serious bacterial, mycobacterial (including tuberculosis), fungal, and viral infections have occurred, including reactivation of hepatitis B and herpes simplex/zoster (shingles). Contact your specialist promptly if you develop fever, chills, or other signs of infection.
Action: Tell your specialist immediately about any signs of infection; do not start ruxolitinib with an active infection without your specialist's specific direction. (1)
Medicines of this class have been associated with an increased risk of serious heart-related events, blood clots (including in the legs and lungs), and certain cancers, particularly in smokers and people with existing cardiovascular risk factors — serious
Symptoms: Medicines of this class have been associated with an increased risk of serious heart-related events, blood clots (including in the legs and lungs), and certain cancers, particularly in smokers and people with existing cardiovascular risk factors.
Action: Discuss your individual risk factors with your specialist before and during treatment; report any new chest pain, leg swelling/pain, or shortness of breath promptly. (1)
Stopping ruxolitinib abruptly, particularly in myelofibrosis, has been associated with a return or worsening of symptoms, which in rare cases has included fever, breathing difficulty, low blood pressure, and serious blood-clotting or multi-organ problems — serious
Symptoms: Stopping ruxolitinib abruptly, particularly in myelofibrosis, has been associated with a return or worsening of symptoms, which in rare cases has included fever, breathing difficulty, low blood pressure, and serious blood-clotting or multi-organ problems.
Action: Never stop or change your dose without talking to your specialist first. If treatment needs to stop, your specialist will usually plan a gradual taper over time rather than an abrupt stop. (1)
Low platelets, low red blood cells (anaemia), and low white blood cells (neutropenia) are expected effects that are monitored with regular blood tests — serious
Symptoms: Low platelets, low red blood cells (anaemia), and low white blood cells (neutropenia) are expected effects that are monitored with regular blood tests.
Action: Attend all scheduled blood tests. Your specialist may pause treatment, adjust your dose, or arrange a transfusion if your blood counts fall too low. (1)
Interactions
- Fluconazole (an antifungal medicine) at doses above 200 mg a day should generally be avoided; at 200 mg a day or less, your ruxolitinib dose may need to be reduced. (1)
- Other medicines described as 'strong CYP3A4 inhibitors' can raise ruxolitinib levels and usually require your dose to be reduced, temporarily stopped, or (outside of GVHD treatment) discontinued -- your specialist will decide. (1)
- Medicines described as 'strong CYP3A4 inducers' can lower ruxolitinib levels and reduce how well it works -- your specialist will monitor you more closely and may adjust your dose. (1)
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
There is no clinical data on ruxolitinib use in pregnant women. Animal studies showed reduced fetal weight at doses that were also toxic to the pregnant animal. Discuss the risks and benefits with your specialist if you are pregnant or planning pregnancy. (1) (2) (3) (4) (5) (6)
Breastfeeding
Breastfeeding is not recommended during treatment and for 2 weeks after the final dose, because of the potential for low platelet counts/anaemia in a breastfed infant and because the drug passes into milk in animal studies. (1) (2) (3) (4) (5) (6)
Children
Approved for graft-versus-host disease in patients aged 12 years and older in the US, and from age 2 in the UK/EU; myelofibrosis and polycythemia vera indications are for adults. (1) (2) (3) (4) (5) (6)
Elderly
No specific dose adjustment is described based on age alone in the sources reviewed; dosing is based on the condition being treated, platelet count, and organ function. (1) (2) (3) (4) (5) (6)
Hepatic_impairment
For myelofibrosis and polycythemia vera, the starting dose should be reduced by 50% in patients with hepatic impairment. No adjustment is needed for GVHD treatment unless there is severe liver involvement. (1) (2) (3) (4) (5) (6)
Renal_impairment
Dose reductions are required for moderate-to-severe kidney impairment; ruxolitinib should generally be avoided in end-stage renal disease not managed with dialysis. (1) (2) (3) (4) (5) (6)
Source_ids
Monitoring
Before starting
- A full blood count (including platelets)
- Assessment for active infection, tuberculosis risk, hepatitis B, and herpes zoster/simplex history
- Cardiovascular risk assessment
- Cholesterol/triglyceride (lipid) levels
During treatment
- Full blood counts approximately every 2-4 weeks when starting treatment, then as directed by your specialist.
- Lipid levels checked 8-12 weeks after starting treatment.
- Ongoing monitoring for signs of infection, blood clots, and heart-related symptoms.
Storage
Store at room temperature as directed on the product label supplied with your specific medicine; keep out of the reach of children.
Professional information
Clinician-facing context only, sourced from the current US prescribing information and UK SmPC; verify against the current full label before prescribing.
United States
Indication: Myelofibrosis (platelet-count based)
Dose summary: Platelets >200x10^9/L: 20 mg BID (JAKAFI) or 44 mg once daily (JAKAFI XR). 100-200x10^9/L: 15 mg BID or 33 mg once daily. 50-<100x10^9/L: 5 mg BID or 11 mg once daily. Polycythemia vera: 10 mg BID or 22 mg once daily. Chronic GVHD: 10 mg BID or 22 mg once daily. Acute GVHD: 5 mg BID or 11 mg once daily. When discontinuing for reasons other than life-threatening toxicity, taper gradually (e.g. reduce JAKAFI by 5 mg BID each week, or JAKAFI XR by 11 mg once daily each week).
Renal context: Dose reductions required for moderate-to-severe renal impairment; avoid in end-stage renal disease not on dialysis. (1)
United Kingdom
Indication: Titration example (product-specific; see current SmPC for full titration schedule)
Dose summary: Oral ruxolitinib starting at 5 mg twice daily, increased to 10 mg twice daily if haematological parameters are stable and no treatment-related toxicity is observed after the first 3 days.
Renal context: Not established in the source reviewed for this dossier; see current UK SmPC for full renal-dosing table. (2)
Hepatic guidance
Reduce starting dose by 50% in hepatic impairment for myelofibrosis/polycythemia vera; no adjustment needed for GVHD treatment without severe liver involvement.
Overdose note
No specific antidote is described in the sources reviewed; manage supportively and seek urgent specialist/emergency guidance for suspected overdose. (1) (2)
Frequently asked questions
Is ruxolitinib available in the US, UK, Europe, Canada, Australia, and New Zealand?
Yes. It is sold as Jakafi (and, since 2026, the extended-release Jakafi XR) in the United States, and as Jakavi in the UK, the European Union, Canada, Australia, and New Zealand. In New Zealand it is government-funded (Pharmac) but restricted to Special Authority and hospital use. (1) (2) (3) (4) (5) (6)
Can I stop taking ruxolitinib if I feel better or have side effects?
No -- do not stop or change your dose without talking to your specialist first. Particularly in myelofibrosis, stopping suddenly has been linked to a serious return or worsening of symptoms. If treatment needs to stop, your specialist will usually plan a gradual taper. (1)
What is Jakafi XR and is it the same as Jakafi?
Jakafi XR is a once-daily extended-release version of ruxolitinib, approved in the United States in 2026. It is not interchangeable milligram-for-milligram with the twice-daily immediate-release Jakafi tablets -- only switch between the two under your specialist's direction. (1)
References
- JAKAFI (ruxolitinib) tablets / JAKAFI XR (ruxolitinib) extended-release tablets -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information, Incyte Corporation · United States · accessed 2026-07-29 · source 1
- Jakavi 5mg/10mg/15mg/20mg Tablets -- Summary of Product Characteristics (SmPC)electronic medicines compendium (emc), United Kingdom -- Novartis Pharmaceuticals UK Ltd · United Kingdom · accessed 2026-07-29 · source 2
- Novartis European Commission approvals for Jakavi (polycythemia vera; acute and chronic GVHD)Novartis corporate press releases documenting European Commission approvals · European Union · accessed 2026-07-29 · source 3
- JAKAVI drug product record (Novartis Pharmaceuticals Canada Inc.)Health Canada Drug Product Database · Canada · accessed 2026-07-29 · source 4
- JAKAVI ruxolitinib (as phosphate) 5mg/20mg tablet blister pack -- ARTG entriesTherapeutic Goods Administration (TGA), Australia -- Australian Register of Therapeutic Goods · Australia · accessed 2026-07-29 · source 5
- Ruxolitinib (Jakavi) Medsafe approval and Pharmac Schedule listingMedsafe (New Zealand regulator) and Pharmac (NZ government medicines funder) · New Zealand · accessed 2026-07-29 · source 6
Brand names by country
Single-ingredient ruxolitinib names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- JAKAFI10 mg, 33 mg, 11 mg, 25 mg, 55 mg, 44 mg, 15 mg, 22 mg · incyte corporation
- OPZELURA15 mg/g · incyte corporation
United Kingdom
- Jakavi (2)MHRA marketing authorisation emc smpc confirmed · 5 mg, 10 mg, 15 mg, 20 mg, 5 mg/mL oral solution · Novartis Pharmaceuticals UK Ltd
Canada
- JAKAVI
Australia
- Jakavi (5)TGA ARTG registered confirmed · 5 mg, 10 mg, 20 mg · Novartis Pharmaceuticals Australia Pty Ltd
New Zealand
- Jakavi (6)Medsafe approved Pharmac funded special authority restricted · 10 mg · Novartis New Zealand Limited
View brands in additional countries.
European Union
Jakavi (3)