Levoleucovorin injection is used in adults and children to prevent harmful effects of methotrexate (Trexall) when methotrexate is used to treat osteosarcoma (cancer that forms in bones). Levoleucovorin injection is also used to treat adults and children who have accidentally received an overdose of methotrexate or similar medications or who are not able to eliminate these medications properly from their bodies. Levoleucovorin injection is also used with fluorouracil (5-FU, a chemotherapy medication) to treat adults with colorectal cancer (cancer that begins in the large intestine) that has spread to other parts of the body. Levoleucovorin injection is in a class of medications called folic acid analogs. It works to prevent the harmful effects of methotrexate by protecting healthy cells, while allowing methotrexate to enter and kill cancer cells. It works to treat colorectal cancer by increasing the effects of fluorouracil.

Levoleucovorin injection comes as a solution (liquid) and as a powder to be mixed with liquid and injected intravenously (into a vein) by a doctor or nurse in a hospital or medical office. When levoleucovorin is used to prevent the harmful effects of methotrexate or treat an overdose of methotrexate, it is usually given every 6 hours, beginning 24 hours after a dose of methotrexate or as soon as possible after an overdose and continuing until laboratory tests show it is no longer needed. When levoleucovorin injection is used to treat colorectal cancer, it is usually given once a day for 5 days in a row as part of a dosing cycle that may be repeated every 4 to 5 weeks.

Before receiving levoleucovorin injection,

• tell your doctor and pharmacist if you are allergic to levoleucovorin injection, leucovorin, folic acid (Folicet, in multivitamins), folinic acid, or any other medications.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: phenobarbital, phenytoin (Dilantin), primidone (Mysoline), or trimethoprim-sulfamethoxazole (Bactrim, Septra). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• your doctor may prescribe levoleucovorin injection with fluorouracil. If you receive this combination of medications, you will be monitored very carefully because levoleucovorin may increase both the benefits and the harmful effects of fluorouracil. If you experience any of the following symptoms, call your doctor immediately: severe diarrhea, stomach pain or cramping, increased thirst, decreased urination, or extreme weakness,
• tell your doctor if you have a dry mouth, dark urine, decreased sweating, dry skin, and other signs of dehydration and if you have or have ever had a buildup of fluid in the chest cavity or the stomach area or kidney disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while receiving levoleucovorin injection, call your doctor.

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Unless your doctor tells you otherwise, continue your normal diet.

Levoleucovorin injection and the medication(s) it is given with may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• mouth sores
• nausea
• vomiting
• loss of appetite
• stomach pain
• diarrhea
• heartburn
• confusion
• numbness, burning, or tingling in the hands or feet
• changes in ability to taste food
• hair loss
• itchy or dry skin
• tiredness

Some side effects can be serious. If you experience any of these symptoms or those in the SPECIAL PRECAUTIONS section, call your doctor immediately or get emergency medical treatment:

• difficulty breathing
• itching
• rash
• fever
• chills

Levoleucovorin injection may cause other side effects. Call your doctor if you have any unusual problems while receiving this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to levoleucovorin injection.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.