Ruxolitinib dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Ruxolitinib is an approved drug that blocks two signalling enzymes, JAK1 and JAK2.
Evidence grade for Ruxolitinib: Moderate. The rule: at least one finished study in people, and at least 100 people who took it. The sum on this page: 1 completed trial, 309 people given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 309
- Human studies
- 1
- Found nothing
- 0
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved as Jakafi pills for two bone marrow cancers, myelofibrosis and polycythaemia vera. Jakafi is also approved for graft-versus-host disease, where donor cells from a transplant attack the body, when steroids have not worked. That covers both sudden and long-term forms. It is also approved as Opzelura cream for eczema (atopic dermatitis) and for the common form of vitiligo (non-segmental). Not approved for ageing, frailty or clearing worn-out cells, and not in a registered trial for any of those.
No first-hand reports gathered yet. That is a gap in what we have collected, not a finding that nothing has been reported.
Goal pages: Muscle and strength, Ageing and longevity, Injury, healing and recovery, Immune system and inflammation, Gut health
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Ruxolitinib is a prescription drug for a bone marrow cancer and some other blood and immune problems. It blocks two signalling enzymes, JAK1 and JAK2. Some people in the ageing world talk about it for calming the inflammation from worn-out cells. It weakens the immune system.
What people take it for
- Calming the inflammation that comes with ageing.
- Less frailty in old age.
- Treating myelofibrosis, a bone marrow cancer, which is what it is approved for.
What studies in people showed
The big human study was in myelofibrosis, a bone marrow cancer. 309 people took the drug or a dummy pill. Spleens shrank by 35 percent or more in 41.9 percent on the drug and 0.7 percent on the dummy. 13 people died on the drug and 24 on the dummy. No human study has tested it for ageing. In old mice, 10 weeks of a drug of the same kind cut inflammation and helped them move better.
What people report
Reports, not study results
The good
- In the cancer study, spleens shrank, symptoms eased, and fewer people died.
The bad
- Low red blood cells and low platelets were the most common problems.
- Both cases where the disease turned into leukaemia were on the drug.
- The cream carries the FDA's strongest warning, for serious infections, death, cancer, heart problems and blood clots.
Where these come from: Everything here is from the cancer study and the drug labels on this page. We have not collected user reports on this one yet.
My bottom line
This is a serious drug that does real work in a serious cancer. Taking it for ageing means years on an immune blocker, based on mice. Not for me.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Ruxolitinib has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Living longer309 people · 1 study
- Cancer and tumoursno headcount stated · 1 study
Animal and lab work, not yet tested in people
Real results, but from animals or cells, not people. What works in a mouse often does not work the same way in a person. This is an approved medicine. So the missing study in people is for this use, not for the drug. Drug makers paid to test it for what it is approved for. The record on this one is set out below.
- Getting stronger1 animal or lab study
- Inflammation1 animal or lab study
32 of the 36 indexed goals have no study of any kind behind Ruxolitinib
No study in people, animals or cells on this page reports a result for these. That does not prove Ruxolitinib does nothing for them. It does mean anything you have heard about Ruxolitinib and one of these did not come from a study cited here.
Show full evidence
What is Ruxolitinib?
Ruxolitinib is an approved drug that blocks two signalling enzymes, JAK1 and JAK2. In old mice it quieted the inflammatory signals from worn-out 'zombie' cells and helped them move better. All of its human evidence is in myelofibrosis, a bone marrow cancer, where it shrinks swollen spleens. The cream version carries the FDA's strongest warning, for serious infections, death, cancer, heart problems and blood clots.
Ruxolitinib is the clearest example of a 'senomorphic' rather than a senolytic. A senolytic kills zombie cells. A senomorphic leaves them alive and shuts down the inflammatory signals they pump out.
Start with the people. There is a large human record, in a blood cancer. In the COMFORT-I study, 309 people with serious myelofibrosis got ruxolitinib or a dummy pill. The main goal was a spleen that shrank by 35 percent or more at 24 weeks. 41.9 percent on ruxolitinib got there, against 0.7 percent on the dummy. Symptoms eased by half or more in 45.9 percent, against 5.3 percent. 13 people died on ruxolitinib, against 24 on the dummy. Low red cells and low platelets were the most common problems. Both people whose disease turned into acute leukaemia were on ruxolitinib.
That is a real drug doing real work in a serious disease, in people who are ill. It is not evidence about a healthy older adult. The side effects are the part that carries over.
The ageing case comes from a 2015 paper by the Mayo Clinic's ageing centre. In a dish, zombie cells from human fat and from human umbilical cord blood vessels pumped out inflammatory signals. Blocking the JAK pathway, with gene tools or JAK-blocking drugs, quieted them. Fluid from untreated zombie fat cells drew immune cells in and inflamed healthy fat. Fluid from treated cells was much less inflammatory. In old mice, 10 weeks of a JAK-blocking drug cut inflammation in fat and across the body, and helped the mice move better. The authors chose their words carefully. They said their results fit with zombie cells playing a part in age-related frailty, and guessed that quieting them might ease frailty.
That is where the ageing evidence stops. No human study of ruxolitinib for ageing, frailty or healthy lifespan is registered.
How does Ruxolitinib work?
Ruxolitinib blocks JAK1 and JAK2, two enzymes inside the cell that pass on signals from a big family of immune messenger receptors. Much of the inflammatory output of zombie cells is made and kept going through that pathway. So blocking JAK1 and JAK2 quiets those signals without killing the zombie cell. Two things follow. The zombie cells stay, so the effect only lasts while you take the drug, unlike a senolytic where the cell is gone. And this pathway is also how the immune system talks to itself, so blocking it weakens the body's defences. That is why the warnings for this drug family read the way they do.
What have studies in people found about Ruxolitinib?
There is a lot of human evidence, and none of it is about ageing. Ruxolitinib has been through large final-stage studies in myelofibrosis, polycythaemia vera (too many red blood cells) and graft-versus-host disease (donor cells attacking the body after a transplant). It is approved because of them. No human study has tested it for frailty, healthy lifespan, age-related inflammation or zombie cells.
- COMFORT-I, 309 people with myelofibrosis: 41.9 percent had their spleen shrink by 35 percent or more at 24 weeks, against 0.7 percent on a dummy pill.
- COMFORT-I symptoms: 45.9 percent cut their symptom score by half or more, against 5.3 percent on the dummy.
- COMFORT-I deaths: 13 on ruxolitinib against 24 on the dummy, about half the risk. This was in people with an aggressive blood cancer, not in healthy older adults.
- Low red cells and low platelets were the most common problems on the drug. Both cases where the disease turned into acute leukaemia were on ruxolitinib.
- The cream, Opzelura, carries a US boxed warning, the strongest kind, for serious infections, more deaths from any cause, lymphoma and other cancers, major heart problems and blood clots. It comes from data on the whole JAK drug family in inflammatory diseases.
- The pill, Jakafi, has no boxed warning. But its label warns about low blood counts, serious infection, skin cancers other than melanoma, raised blood fats, major heart problems, blood clots and new cancers, especially in current or past smokers.
- No registered human study of ruxolitinib for ageing, frailty or healthy lifespan was found.
What this does not tell you: None of this tells you what ruxolitinib does to a healthy older person. The people studied had a life-shortening blood cancer, and that changes what risk is worth taking. A drug that weakens the immune system and raises the risk of infection, heart problems and cancer is a fair trade against myelofibrosis. It is a poor trade against the ordinary inflammation of ageing. The mouse data are about how well mice moved over 10 weeks, not how long they lived. And because a senomorphic quiets zombie cells instead of removing them, any benefit would need dosing forever, with the risks running the whole time.
The state of the research
The gap between what ruxolitinib has been shown to do and what people talk about it doing is unusually wide. The boxed warning belongs on the same page as the anti-ageing claim, not in a footnote.
The safety signal for this drug family is real, and it came from a proper study. After safety findings in inflammatory diseases, a boxed warning was put on the whole JAK-blocker family: serious infections, more deaths from any cause, cancer, major heart problems and blood clots. It appears on the ruxolitinib cream label. The pill, approved earlier and for cancer, has no boxed warning. But its label still warns about low blood counts, serious infection, skin cancer, heart problems, blood clots and new cancers. A person thinking about a JAK blocker for the inflammation of ageing is much closer to the inflammatory-disease patients behind the warning than to the cancer patients behind the good results.
The senomorphic versus senolytic difference also changes the risk sums. A senolytic is given in short bursts, because the cells it kills take time to come back, so you are only exposed now and then. A senomorphic only works while it is in you. That means taking an immune-weakening drug nonstop, forever, for a benefit so far shown only in old mice.
The evidence, in charts
Fig. 1a · how many people
309people, across 1 study in people cited here
| Study | People | Share |
|---|---|---|
| COMFORT-I, New England Journal of Medicine 2012 | 309 | 100% |
The whole total is one study of 309. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. 1 more study in people gives no headcount and is not counted here. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
2 of 4 sources here are studies in people. The rest are not.
- Study in people · done in people250%
- Animal study · done in animals125%
- Review of studies · sums up other studies125%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 4 different years, 2012 to 2017, counted from the list of sources on this page. The newest source on file is from 2017, more than five years ago. Research on it may have gone quiet.
Fig. 3 · legal status at a glance
US
Approved
UK
Approved
AU
Approved
CA
Approved
Approved in all four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 5 · what the molecule is
- Kind of compound
- Small molecule
- Molecule weight
- 306.4 Da as the free base. Supplied as the phosphate salt.
- Half-life
- About 3 hoursShort, 1 to 6 hours
- Chain length
- None on file
No amino acid sequence is on file for Ruxolitinib, which is expected: a small molecule is not built from amino acids.
The studies we cite
- Study in people2012A double-blind, placebo-controlled trial of ruxolitinib for myelofibrosis
Ruxolitinib worked in a blood cancer, and that is the only thing this trial shows. Just over three hundred people with a serious bone marrow disease got either the drug or a dummy pill, and nobody involved knew which. Spleens shrank sharply in four in ten on the drug, against almost nobody on the dummy. Symptoms eased for nearly half. Fewer people died on the drug. Low red cells and low platelets were common. Both cases that turned into leukaemia were on the drug.
COMFORT-I, NCT00952289, 309 patients with intermediate-2 or high-risk myelofibrosis. Spleen volume reduction of at least 35 percent at 24 weeks: 41.9 percent on ruxolitinib against 0.7 percent on placebo. Total symptom score improved by at least 50 percent in 45.9 percent against 5.3 percent. Thirteen deaths on ruxolitinib against 24 on placebo (hazard ratio 0.50, 95 percent CI 0.25 to 0.98). Anaemia and thrombocytopenia were the commonest adverse events; both transformations to acute myeloid leukaemia were in the ruxolitinib arm. This is a cancer trial, not an ageing trial.
- Study in people2017Long-term treatment with ruxolitinib for patients with myelofibrosis: 5-year update from the randomized, double-blind, placebo-controlled, phase 3 COMFORT-I trial
Five years on, the same cancer trial still favours the drug. Spleen shrinkage lasted a median of just over three years. People started on ruxolitinib lived longer than those started on the dummy pill, even though most of the dummy group switched onto the drug part way through. Tiredness and diarrhoea were the common complaints. Low red cells and low platelets nearly all appeared in the first six months. Everyone here had the same bone marrow cancer, and nothing in it measures ageing.
The five-year follow-up of the same myelofibrosis trial, reporting durability of spleen response and long-term safety in that population. Still a cancer population, still no ageing endpoint.
- Review of studies2016Perspective: Targeting the JAK/STAT pathway to fight age-related dysfunction
A review making the case for blocking the JAK pathway to slow ageing, and listing what is still unknown. It is an opinion piece, not new data.
A review setting out the case for JAK/STAT inhibition as a geroscience strategy and its unknowns. A perspective article, not new data.
- Animal study2015JAK inhibition alleviates the cellular senescence-associated secretory phenotype and frailty in old age
In human cells in a dish and in old mice. Blocking the JAK pathway quieted the inflammatory signals from zombie cells. In old mice, 10 weeks of a JAK-blocking drug cut inflammation and helped them move better. There is no result in people.
Human cells in culture plus aged mice. Senescent human preadipocytes and HUVECs developed a SASP that was suppressed by JAK-pathway RNAi or JAK inhibitors, and conditioned medium from JAK-inhibitor-treated senescent cells was much less proinflammatory. Giving a JAK inhibitor to aged mice for 10 weeks alleviated adipose and systemic inflammation and enhanced physical function. The authors state their findings are consistent with a possible contribution of senescent cells to age-related frailty and speculate about SASP inhibition; they do not report a human outcome.
Common questions
Has Ruxolitinib been tested in people?
Yes. 309 people given it across 1 completed trial cited here, 0 of which found nothing. Ruxolitinib is an approved drug that blocks two signalling enzymes, JAK1 and JAK2.
What is the Ruxolitinib dosage?
Approved medicine. No human dose established for unlabelled uses. Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose. FDA-approved as Jakafi pills for two bone marrow cancers, myelofibrosis and polycythaemia vera. Jakafi is also approved for graft-versus-host disease, where donor cells from a transplant attack the body, when steroids have not worked. That covers both sudden and long-term forms. It is also approved as Opzelura cream for eczema (atopic dermatitis) and for the common form of vitiligo (non-segmental). Not approved for ageing, frailty or clearing worn-out cells, and not in a registered trial for any of those.
Is Ruxolitinib FDA-approved?
FDA-approved as Jakafi pills for two bone marrow cancers, myelofibrosis and polycythaemia vera. Jakafi is also approved for graft-versus-host disease, where donor cells from a transplant attack the body, when steroids have not worked. That covers both sudden and long-term forms. It is also approved as Opzelura cream for eczema (atopic dermatitis) and for the common form of vitiligo (non-segmental). Not approved for ageing, frailty or clearing worn-out cells, and not in a registered trial for any of those.
Does ruxolitinib slow ageing?
Nobody knows in people. In old mice, 10 weeks of a JAK-blocking drug cut inflammation and helped them move better. No human study has tested it for ageing, frailty or healthy lifespan.
Is it a senolytic?
No. It is a senomorphic. It does not kill zombie cells. It quiets the inflammatory signals they send out, so the effect lasts only as long as you keep taking it.
What are the risks?
Serious ones. The cream carries a US boxed warning, the strongest kind, for serious infections, more deaths from any cause, lymphoma and other cancers, major heart problems and blood clots. The pill has no boxed warning, but its label warns about low blood counts, serious infection, skin cancers other than melanoma, raised blood fats, heart problems, blood clots and new cancers. Low red cells and low platelets are the most common problems on the drug.
What is it actually approved for?
As a pill: myelofibrosis, polycythaemia vera, and graft-versus-host disease that steroids did not fix. As a cream: eczema (atopic dermatitis) and patchy loss of skin colour (non-segmental vitiligo). Nothing to do with ageing.
Could I take a low dose for inflammation?
No study tells you what dose to use, for how long, or what it would do. It is a prescription drug that weakens the immune system. The people behind the safety warning for this drug family were taking JAK blockers for inflammatory conditions, which is the closest match to that use.