Busulfan belongs to the group of cancer-fighting medications called antineoplastics, and specifically to the group of antineoplastics called alkylating agents. It is used to treat leukemia (cancer of white blood cells). Busulfan prevents the growth of cancer cells by interfering with the genetic material DNA, which is necessary for the reproduction of cells.

It can also be used in combination with other chemotherapy regimens prior to stem cell transplants for certain leukemias, lymphomas (cancer of the lymph cells), multiple myeloma (cancer of the plasma cells), and other genetic conditions that have not responded to other therapies or are very aggressive.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose and dosing schedule of busulfan varies according to the specific type of cancer being treated, the response to therapy, other medications or treatments being used, and is also based on body size. Busulfan is either taken as oral tablet(s) daily or injected into a vein through a site on the skin that has been specially prepared for this purpose.

The dose should be taken at the same time each day to have the best effect. Your doctor may want you to drink extra fluids while taking this medication to prevent kidney problems.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor.

This medication may cause nausea, vomiting, and loss of appetite, but it is important that you continue to use the medication. Do not stop taking it without talking with your doctor. If you vomit shortly after taking a dose of this medication, call your doctor for instructions on whether to skip that dose or to take another dose.

If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

As well as interfering with the genetic material DNA of cancer cells, busulfan can interfere with some of your normal cells. This can cause a number of side effects such as hair loss and mouth sores. Keep track of any side effects and report them to your doctor at your next appointment. 

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Each white, film-coated, round, biconvex tablet, marked with "GX EF3" on one side and "M" on the other, contains 2 mg of busulfan. Nonmedicinal ingredients: anhydrous lactose, magnesium stearate, and pregelatinized starch; film coating: hypromellose (hydroxypropyl methylcellulose), titanium dioxide, and triacetin.

Do not take this medication if you:

• are allergic to busulfan or any ingredients of this medication
• have a low platelet count
• have a low white blood cell count
• have not responded well to busulfan in the past

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• anxiety
• constipation
• darkening of skin
• decreased sexual ability
• diarrhea
• dry eyes
• dry mouth
• dry skin
• fatigue
• hair loss
• headache
• heartburn
• increased skin pigmentation
• itching
• loss of appetite
• missed or irregular menstrual periods
• mouth sores
• muscle and joint aches
• nausea
• rash
• skin injury after radiation
• sleeping problems
• weight loss
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• changes to tooth development in children (e.g., white spots, pits, grooves, and smaller-than-normal permanent teeth)
• decreased testicle size
• decreased fertility
• delayed puberty (adolescents)
• dizziness
• enlarged breast tissue (men)
• lightheadedness
• lower back or side pain
• persistent congestion
• persistent cough with shortness of breath
• puffiness or swelling around the face
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of bladder inflammation (e.g., pain when passing urine, blood in the urine)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of decreased adrenal gland function (e.g., weakness, fatigue, weight loss, nausea, vomiting, dark patches on skin)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of heart problems (e.g., fast, irregular heartbeat or pulse; chest pain; sudden weight gain; difficulty breathing; leg swelling)
• signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine, change of urine colour)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• skin reactions (e.g., reddish, painful, tender lumps under the front of the leg below the knee, dry skin, rash, itchiness, fragile skin)
• swelling of the fingers, hands, arms, lower legs, or feet
• swollen, inflamed tongue
• symptoms of another cancer (e.g., tiredness, fever, night sweats, bone or joint pain, infection, unusual bruising or bleeding)
• symptoms of infection (e.g., fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• symptoms of lung inflammation (e.g., shortness of breath, cough, fever)
• symptoms of myasthenia gravis (e.g., rapid fatigue of muscles, weakness, drooping eye lids, difficulty speaking or swallowing, or use of arms and legs)
• tingling in the lower legs, hands, or feet
• vision problems (e.g., blurred vision, double vision, cloudiness)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• bleeding in the stomach or digestive system (e.g., bloody, black, or tarry stools, spitting up of blood, vomiting blood or material that looks like coffee grounds)
• chest pain
• seizures
• signs of a serious allergic reaction (e.g., hives; difficulty breathing or swallowing; or swelling of the face, lips, tongue, or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Anemia: Busulfan may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.

Blood clotting: This medication can reduce the number of platelet cells in the blood. Platelets help the blood to clot, and a shortage could make you bleed more easily.

Tell your doctor about any signs that your blood is not clotting as quickly as usual. Symptoms include black and tarry stools, blood in the urine, easy bruising, or cuts that won't stop bleeding.

Fertility: Sterility may occur with the use of busulfan. Talk to your doctor about options for preserving fertility for the future.

Infection: As well as killing cancer cells, busulfan can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people who have contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.

Liver: People taking busulfan may have changes in liver function that produce abnormal liver test results. It may also cause blockage of some of the small blood vessels in the liver. Your doctor will monitor you for this with blood tests. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Lung disease: This medication may in rare cases cause a form of lung disease that develops after your treatment with busulfan has been completed. Contact your doctor immediately if you develop a persistent cough, shortness of breath, or fever. Routine breathing tests may be required.

Other cancers: The use of busulfan may increase your risk of developing another type of cancer, such as leukemias and tumours. Discuss any concerns you may have with your doctor.

Seizures: High doses of busulfan can increase the risk of seizures. If you have a history of epilepsy or medical conditions that increase the risk of seizures, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Vaccines: Live vaccines such as yellow fever, BCG, cholera, typhoid, varicella, meningococcal, and diphtheria should not be given while you are receiving busulfan. They work by administering a small amount of live bacterium into the body to cause the body to develop defenses against them. When they are given at the same time as a medication that reduces the strength of your immune system, it may cause a severe infection.

Other vaccines given when you are receiving this medication may not work well enough to protect you from infections. Talk to your doctor about which vaccinations you need before starting treatment.

Pregnancy: There is a possibility of birth defects if either parent is taking busulfan at the time of conception, or if it is taken during pregnancy. Effective birth control should be practiced while using this medication and should be continued for 6 months after treatment with busulfan is complete. If you become pregnant while taking this medication, talk to your doctor immediately.

Breast-feeding: It is not known if busulfan passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.