Leucovorin is used to prevent harmful effects of methotrexate (Rheumatrex, Trexall; cancer chemotherapy medication) when methotrexate is used to treat certain types of cancer. Leucovorin is also used to treat people who have accidentally received an overdose of methotrexate or similar medications. Leucovorin is in a class of medications called folic acid analogs. It works by protecting healthy cells from the effects of methotrexate or similar medications while allowing methotrexate to enter and kill cancer cells.

Leucovorin comes as a tablet to take by mouth. It is usually taken every 6 hours until laboratory tests show it is no longer needed. Sometimes leucovorin is taken on a different schedule, depending on the reason it is needed. Take leucovorin at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take leucovorin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

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

Before taking leucovorin,

• Tell your doctor and pharmacist if you are allergic to leucovorin, levoleucovorin, folic acid (Folicet, in multivitamins), any other medications, or any of the ingredients in leucovorin tablets. Ask your pharmacist for a list of the ingredients.
• Tell your doctor and pharmacist what 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: certain medications for seizures such as phenobarbital, phenytoin (Dilantin), and primidone (Mysoline); and trimethoprim-sulfamethoxazole (Bactrim, Septra). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• Tell your doctor if you have anemia (low number of red blood cells) caused by lack of vitamin B12 or inability to absorb vitamin B12. Your doctor will not prescribe leucovorin to treat this type of anemia.
• Tell your doctor if you have or have ever had a buildup of fluid in the chest cavity or the stomach area or kidney disease. Also tell your doctor if you are nauseated.
• Tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking leucovorin, call your doctor.

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

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:

• Diarrhea
• Rash
• Hives
• Itching
• Difficulty breathing or swallowing

Leucovorin may cause other side effects. Call your doctor if you have any unusual problems while taking 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).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

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.

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

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

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.