SIDE EFFECTS: See also Warning section. Darkening skin or dry mouth may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Many people using this medication develop serious side effects. However, your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Careful monitoring by your doctor may decrease your risk. Tell your doctor right away if you have any serious side effects, including: signs of liver disease (such as persistent nausea/vomiting, severe stomach/abdominal pain, yellowing skin/eyes, dark urine), seizures, unusual/extreme tiredness, painful urination, toe/joint pain, fainting, fast/pounding heartbeat, cloudy/blurred vision. Busulfan has rarely caused very serious (possibly fatal) lung disease. This may occur after months to years of using busulfan. Tell your doctor right away if you develop symptoms of lung disease, including chest pain, shortness of breath, persistent cough. Busulfan may cause other cancers (such as acute leukemia, tumors). Consult your doctor for more details. Tell your doctor right away if you notice any symptoms of cancer, including unusual lumps, sudden weight loss. This medication may affect the ovaries, possibly reducing fertility and causing hormone changes (such as missed menstrual periods). Talk to your doctor for more details. This medication can decrease sperm production and shrink the testicles, effects that may lower male fertility. Talk to your doctor for more details. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking busulfan, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: blood/bone marrow disorders (such as bone marrow suppression, neutropenia, thrombocytopenia, anemia), brain disorders (such as seizures, head injury). Busulfan can make you more likely to get infections or may worsen any current infections. Therefore, wash your hands well to prevent the spread of infection. Avoid contact with people who have infections that may spread to others (such as chickenpox, measles, flu). Consult your doctor if you have been exposed to an infection or for more details. Do not have immunizations/vaccinations without the consent of your doctor. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose). To lower the chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). In female children, this medication may prevent puberty. Contact the doctor for more information. This medication may make it harder for females to become pregnant or for males to father children. Discuss with your doctor for more details. Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using busulfan. Busulfan may harm an unborn baby. Men with female partners of childbearing age should use reliable forms of birth control while using this medication and for at least 3 months after stopping treatment. Women of childbearing age should ask about reliable forms of birth control while using this medication and for at least 6 months after stopping treatment. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication. It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: The effects of some drugs can change if you take other drugs or herbal products at the same time. This can increase your risk for serious side effects or may cause your medications not to work correctly. These drug interactions are possible, but do not always occur. Your doctor or pharmacist can often prevent or manage interactions by changing how you use your medications or by close monitoring. To help your doctor and pharmacist give you the best care, be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products) before starting treatment with this product. While using this product, do not start, stop, or change the dosage of any other medicines you are using without your doctor's approval. Some products that may interact with this drug include: acetaminophen, itraconazole, nalidixic acid, thioguanine. This document does not contain all possible drug interactions. Keep a list of all the products you use. Share this list with your doctor and pharmacist to lessen your risk for serious medication problems.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose include: easy bruising/bleeding, pale skin, unusual tiredness.