jakafi
Jakafi (Ruxolitinib Phosphate) is a janus kinase inhibitor used to treat Polycythemia Vera, Primary Myelofibrosis.
Ruxolitinib Phosphate · by Incyte Corp
Key facts
- Active ingredient
- Ruxolitinib Phosphate
- Drug class
- Janus Kinase Inhibitor
- Form
- Tablet
- Strength
- Ruxolitinib Phosphate EQ 10MG Base · Ruxolitinib Phosphate EQ 15MG Base · Ruxolitinib Phosphate EQ 20MG Base · Ruxolitinib Phosphate EQ 25MG Base · Ruxolitinib Phosphate EQ 5MG Base
- Type
- Prescription (Rx)
- Brand or generic
- Brand-name
- May treat
- polycythemia vera, primary myelofibrosis
- Manufacturer
- Incyte Corp
- FDA application
- NDA202192
What is Jakafi?
From the FDA label:Ruxolitinib phosphate is a kinase inhibitor with the chemical name ( R )-3-(4-(7 H -pyrrolo[2,3- d ]pyrimidin-4-yl)-1 H -pyrazol-1-yl)-3-cyclopentylpropanenitrile phosphate and a molecular weight of 404.36. Ruxolitinib phosphate has the following structural formula: Ruxolitinib phosphate is a white to off-white to light pink powder and is soluble in aqueous buffers across a pH range of 1 to 8. JAKAFI (ruxolitinib) tablets are for oral administration. Each tablet contains 5 mg, 10 mg, 15 mg, 20 mg, or 25 mg of ruxolitinib free base, equivalent to 6.6 mg, 13.2 mg, 19.8 mg, 26.4 mg, or 33 mg of ruxolitinib phosphate, respectively, and the following inactive ingredients: colloidal silicon dioxide, hydroxypropyl cellulose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, povidone and sodium starch glycolate. JAKAFI XR (ruxolitinib) extended-release tablets are for oral administration. Each tablet contains 11 mg, 22 mg, 33 mg, 44 mg, or 55 mg of ruxolitinib free base equivalent to 14.5 mg, 29 mg, 43.6 mg, 58.1 mg, or 72.6 mg of ruxolitinib phosphate, respectively, and the following inactive ingredients: colloidal silicon dioxide, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and sodium stearyl fumarate. In addition, the film coating contains the following inactive ingredients: colorants (black iron oxide, red iron oxide, and…
How to use
Doses should be individualized based on safety and efficacy. Starting doses per indication are noted below. Myelofibrosis ( 2.2 ) The starting dose of JAKAFI/JAKAFI XR is based on patient’s baseline platelet count: • Greater than 200 × 10 9 /L: JAKAFI 20 mg given orally twice daily or JAKAFI XR 44 mg given orally once daily. • 100 x 10 9 /L to 200 x 10 9 /L: JAKAFI 15 mg given orally twice daily or JAKAFI XR 33 mg given orally once daily. • 50 x 10 9 /L to less than 100 x 10 9 /L: JAKAFI 5 mg given orally twice daily or JAKAFI XR 11 mg given orally once daily. Polycythemia Vera ( 2.3 ) The starting dose of JAKAFI is 10 mg given orally twice daily or JAKAFI XR 22 mg given orally once daily. Acute Graft-Versus-Host Disease ( 2.4 ) The starting dose of JAKAFI is 5 mg given orally twice daily or JAKAFI XR 11 mg given orally once daily. Chronic Graft-Versus-Host Disease ( 2.5 ) The starting dose of JAKAFI is 10 mg given orally twice daily or JAKAFI XR 22 mg given orally once daily. 2.1 Monitoring to Assess Safety Prior to JAKAFI/JAKAFI XR treatment: Perform a complete blood count (CBC) [see Warnings and Precautions ( 5.1 )] . Inquire about past infections, including tuberculosis, herpes simplex, herpes zoster, and hepatitis B [see Warnings and Precautions ( 5.2 )] . During treatment with JAKAFI/JAKAFI XR : Perform a CBC every 2 to 4 weeks until doses are stabilized, and then as…
Side effects
The following clinically significant adverse reactions are discussed in greater detail in other sections of the labeling: Thrombocytopenia, Anemia and Neutropenia [see Warnings and Precautions ( 5.1 )] Risk of Infection [see Warnings and Precautions ( 5.2 )] Symptom Exacerbation Following Interruption or Discontinuation of Treatment [see Warnings and Precautions ( 5.3 )] Non-Melanoma Skin Cancer [see Warnings and Precautions ( 5.4 )] Lipid Elevations [ see Warnings and Precautions ( 5.5 )] Major Adverse Cardiovascular Events (MACE) [ see Warnings and Precautions ( 5.6 )] Thrombosis [ see Warnings and Precautions ( 5.7 )] Secondary Malignancies [ see Warnings and Precautions ( 5.8 )] In myelofibrosis and polycythemia vera, the most common hematologic adverse reactions (incidence > 20%) are thrombocytopenia and anemia. The most common nonhematologic adverse reactions (incidence ≥ 15%) are bruising, dizziness, headache, and diarrhea. ( 6.1 ) In acute graft-versus-host disease, the most common hematologic adverse reactions (incidence > 50%) are anemia, thrombocytopenia, and neutropenia. The most common nonhematologic adverse reactions (incidence > 50%) are infections (pathogen not specified) and edema. ( 6.1 ) In chronic graft-versus-host disease, the most common hematologic adverse reactions (incidence > 35%) are anemia and thrombocytopenia. The most common nonhematologic adverse…
Warnings
Important safety information
Thrombocytopenia, Anemia, and Neutropenia: Manage by dose reduction or interruption, or transfusion. ( 5.1 ) Risk of Infection: Assess patients for signs and symptoms of infection and initiate appropriate treatment promptly. Serious infections should have resolved before starting therapy with JAKAFI/JAKAFI XR. ( 5.2 ) Symptom Exacerbation Following Interruption or Discontinuation: Manage with supportive care and consider resuming treatment with JAKAFI/JAKAFI XR. ( 5.3 ) Risk of Non-Melanoma Skin Cancer: Perform periodic skin examinations. ( 5.4 ) Lipid Elevations: Assess lipid levels 8 to 12 weeks from start of therapy and treat as needed. ( 5.5 ) Major Adverse Cardiovascular Events (MACE): Monitor for development of MACE. ( 5.6 ) Thrombosis: Evaluate and treat symptoms of thrombosis promptly. ( 5.7 ) Secondary Malignancies: Monitor for development of secondary malignancies, particularly in patients who are current or past smokers. ( 5.8 ) 5.1 Thrombocytopenia, Anemia, and Neutropenia Treatment with JAKAFI/JAKAFI XR can cause thrombocytopenia, anemia, and neutropenia [ see Adverse Reactions ( 6.1 )] . Manage thrombocytopenia by reducing the dose or temporarily interrupting JAKAFI/JAKAFI XR. Platelet transfusions may be necessary [ see Dosage and Administration ( 2 ) ] . Patients developing anemia may require blood transfusions and/or dose modifications of JAKAFI/JAKAFI XR. Severe neutropenia (ANC less than 0.5 × 10 9 /L) was generally reversible by withholding JAKAFI/JAKAFI XR until recovery. Perform a pre-treatment CBC and monitor CBCs every 2 to 4 weeks until doses are stabilized, and then as clinically indicated [ see Dosage and Administration ( 2 )] . 5.2 Risk of Infection Serious bacterial, mycobacterial, fungal, and viral infections have occurred [ see Adverse Reactions ( 6.1 )] . Delay starting therapy with JAKAFI/JAKAFI XR until active serious infections have resolved. Observe patients receiving JAKAFI/JAKAFI XR for signs and symptoms of infection and manage promptly. Use active surveillance and prophylactic antibiotics according to clinical guidelines. Tuberculosis Tuberculosis infection has been reported in patients receiving JAKAFI. Observe patients receiving JAKAFI/JAKAFI XR for signs and symptoms of active tuberculosis and manage promptly. Prior to initiating JAKAFI/JAKAFI XR, patients should be evaluated for tuberculosis risk factors, and those at higher risk should be tested for latent infection. Risk factors include, but are not limited to, prior residence in or travel to countries with a high prevalence of tuberculosis, close contact with a person with active tuberculosis, and a history of active or latent tuberculosis where an adequate course of treatment cannot be confirmed. For patients with evidence of active or latent tuberculosis, consult a physician with expertise in the treatment of tuberculosis before starting JAKAFI/JAKAFI XR. The decision to continue JAKAFI/JAKAFI XR during treatment of active tuberculosis should be based on the overall risk-benefit determination. Progressive Multifocal Leukoencephalopathy Progressive multifocal leukoencephalopathy (PML) has occurred with JAKAFI treatment. If PML is suspected, stop JAKAFI/JAKAFI XR and evaluate. Herpes Zoster and Herpes Simplex Herpes zoster infection has been reported in patients receiving JAKAFI [see Adverse Reactions ( 6.1 )] . Advise patients about early signs and symptoms of herpes zoster and to seek treatment as early as possible if suspected. Herpes simplex virus reactivation and/or dissemination has been reported in patients receiving JAKAFI [see Adverse Reactions ( 6.2 )] . Monitor patients for the development of herpes simplex infections. If a patient develops evidence of dissemination of herpes simplex, consider interrupting treatment with JAKAFI/JAKAFI XR; patients should be promptly treated and monitored according to clinical guidelines. Hepatitis B Hepatitis B viral load (HBV-DNA titer) increases, with or without associated elevations in alanine aminotransferase and aspartate aminotransferase, have been reported in patients with chronic HBV infections taking JAKAFI. The effect of JAKAFI/JAKAFI XR on viral replication in patients with chronic HBV infection is unknown. Patients with chronic HBV infection should be treated and monitored according to clinical guidelines. 5.3 Symptom Exacerbation Following Interruption or Discontinuation of Treatment Following discontinuation of JAK-inhibitors, including JAKAFI/JAKAFI XR, signs and symptoms from myeloproliferative neoplasms may flare. Some patients with MF have experienced one or more of the following after discontinuing JAK-inhibitors: fever, respiratory distress, hypotension, disseminated intravascular coagulation, or multi-organ failure. If one or more of these signs and symptoms occur after discontinuation of JAKAFI/JAKAFI XR, or while tapering the dose, evaluate for and treat any intercurrent illness and consider restarting or increasing the dose of JAKAFI/JAKAFI XR. Instruct patients not to interrupt or discontinue therapy without consulting their healthcare provider. When discontinuing or interrupting therapy with JAKAFI/JAKAFI XR for reasons other than life‑threatening toxicities, consider tapering the dose of JAKAFI/JAKAFI XR gradually rather than discontinuing abruptly [see Dosage and Administration ( 2.8 )] . 5.4 Non-Melanoma Skin Cancer (NMSC) Non-melanoma skin cancers including basal cell, squamous cell, and Merkel cell carcinoma have occurred in patients treated with JAKAFI/JAKAFI XR. Perform periodic skin examinations. 5.5 Lipid Elevations Treatment with JAKAFI has been associated with increases in lipid parameters including total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides [see Adverse Reactions ( 6.1 )] . The effect of these lipid parameter elevations on cardiovascular morbidity and mortality has not been determined in patients treated with JAKAFI/JAKAFI XR. Assess lipid parameters approximately 8 to 12 weeks following initiation of JAKAFI/JAKAFI XR therapy. Monitor and treat according to clinical guidelines for the management of hyperlipidemia. 5.6 Major Adverse Cardiovascular Events (MACE) Another JAK inhibitor has increased the risk of MACE, including cardiovascular death, myocardial infarction, and stroke (compared to those treated with TNF blockers) in patients with rheumatoid arthritis, a condition for which JAKAFI/JAKAFI XR is not indicated. Consider the benefits and risks for the individual patient prior to initiating or continuing therapy with JAKAFI/JAKAFI XR particularly in patients who are current or past smokers and patients with other cardiovascular risk factors. Patients should be informed about the symptoms of serious cardiovascular events and the steps to take if they occur. 5.7 Thrombosis Another JAK-inhibitor has increased the risk of thrombosis, including deep venous thrombosis (DVT), pulmonary embolism (PE), and arterial thrombosis (compared to those treated with TNF blockers) in patients with rheumatoid arthritis, a condition for which JAKAFI/JAKAFI XR is not indicated. In patients with MF and PV treated with JAKAFI in clinical trials, the rates of thromboembolic events were similar in JAKAFI and control treated patients. Patients with symptoms of thrombosis should be promptly evaluated and treated appropriately. 5.8 Secondary Malignancies Another JAK-inhibitor has increased the risk of lymphoma and other malignancies excluding NMSC (compared to those treated with TNF blockers) in patients with rheumatoid arthritis, a condition for which JAKAFI/JAKAFI XR is not indicated. Patients who are current or past smokers are at additional increased risk. Consider the benefits and risks for the individual patient prior to initiating or continuing therapy with JAKAFI/JAKAFI XR, particularly in patients with a known secondary malignancy (other than a successfully treated NMSC), patients who develop a malignancy, and patients who are current or past…
Who should not take Jakafi
None. None. ( 4 )
Overdose — what happens if you take too much
There is no known antidote for overdoses with JAKAFI/JAKAFI XR. Single doses up to 200 mg have been given with acceptable acute tolerability. Higher than recommended repeat doses are associated with increased myelosuppression including leukopenia, anemia, and thrombocytopenia. Appropriate supportive treatment should be given. Hemodialysis is not expected to enhance the elimination of JAKAFI/JAKAFI XR.
U.S. Poison Control: call or text 1-800-222-1222 (free, 24/7). In an emergency call 911. From the FDA label; not medical advice.
Interactions
Fluconazole: Avoid concomitant use with fluconazole doses greater than 200 mg. Reduce JAKAFI/JAKAFI XR dosage with fluconazole doses less than or equal to 200 mg. ( 2.6 , 7 ) Strong CYP3A4 Inhibitors: Reduce, interrupt, or discontinue JAKAFI/JAKAFI XR doses as recommended except in patients with acute or chronic graft-versus-host-disease. ( 2.6 , 7 ) 7.1 Effect of Other Drugs on JAKAFI/JAKAFI XR Fluconazole Concomitant use of JAKAFI/JAKAFI XR with fluconazole increases ruxolitinib exposure [ see Clinical Pharmacology ( 12.3 )] , which may increase the risk of exposure-related adverse reactions. Avoid concomitant use of JAKAFI/JAKAFI XR with fluconazole doses of greater than 200 mg daily. Reduce the JAKAFI/JAKAFI XR dosage when used concomitantly with fluconazole doses of less than or equal to 200 mg [ see Dosage and Administration ( 2.6 )] . Strong CYP3A4 Inhibitors Concomitant use of JAKAFI/JAKAFI XR with strong CYP3A4 inhibitors increases ruxolitinib exposure [ see Clinical Pharmacology ( 12.3 )] , which may increase the risk of exposure-related adverse reactions. Reduce the JAKAFI/JAKAFI XR dosage when used concomitantly with strong CYP3A4 inhibitors except in patients with aGVHD or cGVHD [ see Dosage and Administration ( 2.6 )] . Strong CYP3A4 Inducers Concomitant use of JAKAFI/JAKAFI XR with strong CYP3A4 inducers may decrease ruxolitinib exposure [ see Clinical Pharmacology ( 12.3 )] , which may reduce efficacy of JAKAFI/JAKAFI XR. Monitor patients frequently and adjust the JAKAFI/JAKAFI XR dose based on safety and efficacy [ see Clinical Pharmacology ( 12.3 )] .
Drug class
How this class works, per Janus kinase-targeting therapies in rheumatology: a mechanisms-based approach - PMC, NCBI.
May treat (source: NIH RxClass)
See how Jakafi ranks — best-rated janus kinase inhibitor for:
Dosage forms
Tablet
The forms currently marketed in the U.S., per the FDA National Drug Code Directory.
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Frequently asked questions
- What does Jakafi treat?
- Jakafi (Ruxolitinib Phosphate) may be used to treat polycythemia vera, primary myelofibrosis, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
- How does Jakafi work?
- Jakafi is a janus kinase inhibitor. JAK inhibitors block Janus kinase enzymes inside immune cells. These enzymes normally pass along messages from inflammatory signals (cytokines) to relay proteins that switch on genes, so blocking them turns down the overactive immune signaling that drives diseases like rheumatoid arthritis.
- Is there a coupon or discount for Jakafi?
- pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Jakafi. To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
- Who makes Jakafi?
- Jakafi is marketed by Incyte Corp. You can see Incyte Corp's full profile, rating, and other products on pharmaranks.
- Is Jakafi a brand-name or generic drug?
- Jakafi is a brand-name product with the active ingredient Ruxolitinib Phosphate.
- Is Jakafi available over the counter?
- No. Jakafi is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
- What forms does Jakafi come in?
- Jakafi is currently marketed as tablet, per the FDA's National Drug Code Directory.
- What class of drug is Jakafi?
- Jakafi is classified as janus kinase inhibitor, kinase inhibitor, per the FDA's Established Pharmacologic Class.
- Is Jakafi FDA-registered?
- Jakafi is on record with the U.S. FDA under application number NDA202192. You can verify this on its official FDA label.
- Is Jakafi safe?
- There's no single safe-or-not verdict, and we don't yet have a composite recall-safety score for Jakafi. Review its FDA-label side effects and warnings below, and always consult a licensed professional.
- What are the side effects of Jakafi?
- Jakafi's side effects are taken directly from its FDA label. From the label: The following clinically significant adverse reactions are discussed in greater detail in other sections of the labeling: Thrombocytopenia, Anemia and Neutropenia [see Warnings and Precautions ( 5.1 )] Risk of Infection [see Warnings and Precautions ( 5.2 )] Symptom Exacerbation Following Interrupti… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.
Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.
What people report to the FDA about RUXOLITINIB PHOSPHATE
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 278 reports naming RUXOLITINIB PHOSPHATE — the active ingredient in Jakafi, and the FDA flagged 94% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- sepsis45 reports
- multiple organ dysfunction syndrome34 reports
- treatment failure34 reports
- acute graft versus host disease33 reports
- adenovirus infection32 reports
- stenotrophomonas infection31 reports
- thrombocytopenia22 reports
- neutropenia20 reports
Read these as a signal, not a rate. A report does not mean RUXOLITINIB PHOSPHATE caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label.
Source: openFDA drug/event (FAERS), retrieved September 26, 2026.
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