Decitabine
About Decitabine
Decitabine — hypomethylating agent — DNA methyltransferase inhibitor
Decitabine is a medicine given by infusion for myelodysplastic syndromes and for acute myeloid leukaemia in adults who are not candidates for intensive chemotherapy. It is a nucleoside analogue rather than a conventional cytotoxic.
How Decitabine works
It is incorporated into DNA in place of cytidine, where it traps and depletes DNA methyltransferase. Losing that enzyme reduces methylation across the genome, and genes that had been silenced by methylation — including genes that normally restrain cell growth — can be expressed again. The effect depends on cells dividing, which is why it is given in repeated cycles rather than as a single course.
What it is licensed for
Intermediate and high-risk myelodysplastic syndromes, and newly diagnosed acute myeloid leukaemia in adults who are not candidates for standard induction chemotherapy.
How it is taken
An intravenous infusion given over several consecutive days, repeated in cycles roughly every four weeks. It is given in a hospital or day-unit setting, not at home. Dosage must be determined by a qualified healthcare provider.
What your prescriber monitors
Full blood count before each cycle and between cycles, since myelosuppression is expected; liver and renal function; and prompt assessment of fever, because neutropenia raises infection risk. Neutrophil and platelet nadirs are anticipated and counts scheduled around them. Renal and hepatic panels precede each cycle. Cytogenetic or bone-marrow reassessment is arranged at intervals agreed with the haematology team.
Important cautions and interactions
Blood counts fall as part of how the medicine works, and infection and bleeding risk rise with them — fever is treated as urgent. Several cycles are usually given before response is assessed, so early cycles are not judged on their own. It can harm a developing baby, and contraception is required.
Where Decitabine sits in its class
Decitabine and azacitidine are the two established hypomethylating agents; azacitidine is incorporated into RNA as well as DNA and is more often given subcutaneously, while decitabine acts on DNA and is given intravenously. Oral combinations of decitabine with cedazuridine now exist as separate licensed products, developed to avoid the rapid breakdown that makes plain decitabine unsuitable by mouth.
What to expect in the first weeks
Counts fall after the first cycle and are typically at their lowest a week or two afterwards, which is when infection and bruising risk peak — take your temperature if you feel unwell and contact the unit the same day if it is raised. Tiredness, nausea, constipation and mouth soreness are common. Transfusion of red cells or platelets between cycles is routine rather than a setback.
Before you start Decitabine
Tell your team about liver or kidney problems, since both affect how the medicine is handled. Mention any active infection before a cycle starts. Agree in advance what to do about fever at home — with low neutrophil counts it is treated as an emergency rather than watched. Ask how many cycles are planned before response is assessed, so the early ones are not judged on their own.
Generic Decitabine and Dacogen
Generic Decitabine contains the same active ingredient as Dacogen®, produced by licensed pharmaceutical manufacturers. The brand name and the price differ, not the molecule.
Decitabine is a prescription-only medicine. A valid prescription is required and every order is reviewed by a licensed pharmacist before dispatch. Used as prescribed by a licensed medical professional.
Frequently asked questions
Why is decitabine given as an infusion rather than a tablet?
It is a nucleoside analogue that is broken down rapidly when swallowed, so it is given intravenously over consecutive days in a hospital or day unit. Oral hypomethylating combinations exist but are separate medicines with their own licences.
Why do several cycles happen before anyone assesses whether it is working?
The mechanism depends on cells dividing and on methylation patterns changing gradually, so effects build over cycles. Assessment after several cycles rather than one is standard practice for this class, and your haematologist will explain the plan for your own treatment.
Why does decitabine lower blood counts?
Suppression of the bone marrow is expected with this medicine rather than an unusual reaction, and counts are checked before and between cycles. Because low neutrophils raise infection risk, any fever during treatment is treated as urgent — contact your team the same day.
Do I need a prescription to order Decitabine?
Yes. Decitabine is a prescription-only medicine. Upload a valid prescription at checkout — every order is reviewed by a licensed pharmacist before dispatch.
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Last updated: October 3, 2026
Medically reviewed by
Mahesh Gupta
Mahesh Gupta is a licensed clinical pharmacist with 15 years of experience. He holds a B.Pharm and M.Pharm from LN Mithila University. At OnlineMeds, he reviews medicine and health content to help ensure it is accurate, evidence-based, and easy to understand.