Busulfan: uses, dosing, side effects & brands
Busulfan is an alkylating drug sold in the U.S. under 3 brand and generic names, for polycythemia vera, bcr-abl positive chronic myelogenous leukemia and primary myelofibrosis. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Alkylating Drug
- Treats (across its forms)
- Polycythemia Vera, Bcr-Abl Positive Chronic Myelogenous Leukemia and Primary Myelofibrosis
- Available as
- Injectable · Solution · Tablet
- Sold as
- 3 products — Busulfan, Busulfex and Myleran
- Prescription?
- Prescription only
- Generic available?
- Yes
- Boxed warning
- Boxed warning
How Myleran is dosed
From the FDA label for Myleran (application NDA009386). Other busulfan products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Busulfan is administered orally. The usual adult dose range for remission induction is 4 to 8 mg, total dose, daily. Dosing on a weight basis is the same for both pediatric patients and adults, approximately 60 mcg/kg of body weight or 1.8 mg/m 2 of body surface, daily. Since the rate of fall of the leukocyte count is dose related, daily doses exceeding 4 mg per day should be reserved for patients with the most compelling symptoms; the greater the total daily dose, the greater is the possibility of inducing bone marrow aplasia. A decrease in the leukocyte count is not usually seen during the first 10 to 15 days of treatment; the leukocyte count may actually increase during this period and it should not be interpreted as resistance to the drug, nor should the dose be increased. Since the leukocyte count may continue to fall for more than 1 month after discontinuing the drug, it is important that busulfan be discontinued prior to the total leukocyte count falling into the normal range. When the total leukocyte count has declined to approximately 15,000/mcL, the drug should be withheld. With a constant dose of busulfan, the total leukocyte count declines exponentially; a weekly plot of the leukocyte count on semi-logarithmic graph paper aids in predicting the time when therapy should be discontinued. With the recommended dose of busulfan, a normal leukocyte count is usually…
Everything below is the FDA label for Myleran (tablet). Busulfan is also sold as injectable and solution, and those are different medicines to take — follow the label for the one you were prescribed.
Myleran side effects
To report SUSPECTED ADVERSE REACTIONS, contact Waylis Therapeutics LLC Toll-Free at 1-888-514-4727 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . Hematological Effects The most frequent, serious, toxic effect of busulfan is dose-related myelosuppression resulting in leukopenia, thrombocytopenia, and anemia. Myelosuppression is most frequently the result of a failure to discontinue dosage in the face of an undetected decrease in leukocyte or platelet counts. Aplastic anemia (sometimes irreversible) has been reported rarely, often following long-term conventional doses and also high doses of MYLERAN. Pulmonary Interstitial pulmonary fibrosis has been reported rarely, but it is a clinically significant adverse effect when observed and calls for immediate discontinuation of further administration of the drug. The role of corticosteroids in arresting or reversing the fibrosis has been reported to be beneficial in some cases and without effect in others. Cardiac Cardiac tamponade has been reported in a small number of patients with thalassemia who received busulfan and cyclophosphamide as the preparatory regimen for bone marrow transplantation (see WARNINGS). One case of endocardial fibrosis has been reported in a 79-year-old woman who received a total dose of 7,200 mg of busulfan over a period of 9 years for the management of chronic myelogenous leukemia. At autopsy, she was…
Who shouldn’t take Myleran
MYLERAN is contraindicated in patients in whom a definitive diagnosis of chronic myelogenous leukemia has not been firmly established. MYLERAN is contraindicated in patients who have previously suffered a hypersensitivity reaction to busulfan or any other component of the preparation.
Myleran drug interactions
Busulfan may cause additive myelosuppression when used with other myelosuppressive drugs. In one study, 12 of approximately 330 patients receiving continuous busulfan and thioguanine therapy for treatment of chronic myelogenous leukemia were found to have portal hypertension and esophageal varices associated with abnormal liver function tests. Subsequent liver biopsies were performed in 4 of these patients, all of which showed evidence of nodular regenerative hyperplasia. Duration of combination therapy prior to the appearance of esophageal varices ranged from 6 to 45 months. With the present analysis of the data, no cases of hepatotoxicity have appeared in the busulfan-alone arm of the study. Long-term continuous therapy with thioguanine and busulfan should be used with caution. Busulfan-induced pulmonary toxicity may be additive to the effects produced by other cytotoxic agents. The concomitant systemic administration of itraconazole to patients receiving high-dose MYLERAN may result in reduced busulfan clearance (see CLINICAL PHARMACOLOGY). Patients should be monitored for signs of busulfan toxicity when itraconazole is used concomitantly with MYLERAN.
Every busulfan product we track (3)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 72/100 | Prescription | Injectable | No data | — | View → | |
| 2 | Not yet rated | Prescription | Injectable | No data | — | View → | |
| 3 | Not yet rated | Prescription | Tablet | No data | — | View → |
What busulfan pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| GX;EF3;M | 2 mg | white | round | — |
Busulfan recalls
From the FDA Enforcement database. A recall covers specific lots — not the drug as a whole.
Busulfan and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for busulfan: levels in milk, effects in breastfed infants, and the drugs it would consider insteadMost sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy. It might be possible to breastfeed safely with busulfan during intermittent therapy with an appropriate period of breastfeeding abstinence. Although minimal data are available to determine an appropriate period to withhold breastfeeding, the drug's terminal half-live of 2.5 hours suggests that at least 24 hours may be sufficient. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk. Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant.
National Institute of Child Health and Human Development, record revised August 16, 2021. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about busulfan
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 15,936 reports naming busulfan, and the FDA flagged 95% 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:
- mucosal inflammation1,088 reports
- graft versus host disease976 reports
- venoocclusive liver disease932 reports
- cytomegalovirus infection885 reports
- acute graft versus host disease862 reports
- febrile neutropenia860 reports
- pyrexia823 reports
- chronic graft versus host disease648 reports
Read these as a signal, not a rate. A report does not mean busulfan 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 section above.
Source: openFDA drug/event (FAERS), retrieved August 25, 2026.
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Frequently asked questions
What is Myleran?
Myleran (Busulfan) is an alkylating drug used to treat Polycythemia Vera, Bcr-Abl Positive Chronic Myelogenous Leukemia, Primary Myelofibrosis.
What kind of drug is busulfan?
The FDA classifies busulfan as an alkylating drug. Alkylating chemotherapy drugs attach chemical groups to a cell's DNA, forming cross-links that lock the two DNA strands together. This damage stops the cell from copying its DNA and dividing, which triggers it to die; because they are not limited to one phase of the cell cycle, they can act on cells whether or not they are actively dividing. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take busulfan with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run busulfan against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is busulfan sold under?
We track 3 busulfan-containing products in the U.S.: Busulfan, Busulfex and Myleran. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does busulfan come in?
Across the brands we track, busulfan is currently marketed as injectable, solution and tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic busulfan?
Yes. Our catalog lists 1 generic busulfan product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.
Has busulfan been recalled?
The FDA's Enforcement database lists 1 recall record whose product description mentions busulfan. The most recent: Busulfan Injection (May 4, 2026). A recall applies to specific lots, not to the drug as a whole — check the record for the affected lot numbers.
Cite this page
- APA
- pharmaranks. (2026, July 24). Busulfan: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/busulfan
- MLA
- “Busulfan: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/busulfan.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for busulfan on DailyMed (NIH) ↗ — including its boxed warning in full.