What is Leucovorin? Uses, warnings & side effects

Medically reviewed by Ashley Wong, Pharm. D.
Licensed Pharmacist
Updated Nov 5, 2025  •  Published Dec 30, 2020
Fact Checked

Leucovorin is a generic prescription drug that is FDA-approved to treat side effects that occur with certain anticancer medications, such as methotrexate. It may also be prescribed to treat certain types of anemia and advanced colon cancer when used with fluorouracil. Leucovorin is available as an oral tablet and injection.

Check our best Leucovorin prices

Leucovorin overview

BRAND NAMES:

  • Wellcovorin

Generic Names:

  • Leucovorin calcium

Uses:

  • Prevents and treats side effects caused by certain kinds of medicines, such as methotrexate (an anti-cancer medicine) 

  • Treats megaloblastic anemia due to low levels of folic acid

  • Treat advanced colon cancer

Therapeutic Classes:

  • Methotrexate rescue, folic acid analog

Forms:

  • Tablet

  • Injection

How it’s taken:

  • Tablet: by mouth

  • Injection: intramuscularly or intravenously

What is Leucovorin used for?

Leucovorin is used to prevent the toxic effects of certain anticancer treatments, including methotrexate. It can also be used to treat certain types of anemia. Lastly, leucovorin is also prescribed with fluorouracil to treat colon cancer.

Key takeaways

  • Take leucovorin exactly as prescribed. Taking more than prescribed can increase your risk of side effects. 

  • If you are taking leucovorin tablets and feel nauseous or are vomiting, let your healthcare provider know. They can switch you to the injection form of the drug to make sure your body absorbs the medication. 

  • Leucovorin may interact with certain seizure medications. Combining these medications can make the seizure medications less effective, which can increase the frequency of your seizures. Tell your healthcare provider if you take any seizure drugs before starting leucovorin. 

  • It isn’t known if leucovorin is safe to take while pregnant or breastfeeding. If you are pregnant, planning to become pregnant, or breastfeeding, talk to a healthcare professional about potential alternative treatments.

What form(s) does Leucovorin come in?

  • Tablet 

    • 5 mg

    • 10 mg

    • 15 mg

    • 25 mg

  • Injection

    • 50 mg

    • 100 mg

    • 200 mg

    • 350 mg

    • 500 mg

What are common Leucovorin dosages?

The dosage of leucovorin depends on the condition being treated. 

  • Methotrexate toxicity: 15 mg or 10 mg/m^2 by mouth, intramuscularly, or intravenously every 6 hours until your methotrexate levels are less than 10^(-8)M

  • Overdosage of anti-folate medications: 5 to 15 mg by mouth daily

  • Megaloblastic anemia due to folic acid deficiency: up to 1 mg daily

  • Colon cancer: 200 mg/m^2 by slow IV infusion over a minimum of three minutes OR 20 mg/m^2 by IV injection

Leucovorin images - What does Leucovorin look like?

  • Leucovorin Calcium
    100mg solution reconstituted

  • Leucovorin Calcium
    200mg solution reconstituted

  • Leucovorin Calcium
    350mg solution reconstituted

  • Leucovorin Calcium
    500mg solution reconstituted

  • Leucovorin Calcium
    50mg solution reconstituted

  • Leucovorin Calcium
    10mg tablet

  • Leucovorin Calcium
    15mg tablet

  • Leucovorin Calcium
    25mg tablet

  • Leucovorin Calcium
    5mg tablet

  • Leucovorin Calcium
    10ml of 100mg/10ml vial

  • Leucovorin Calcium
    50ml of 500mg/50ml vial

How to take Leucovorin

  • If you vomit right after you take this medicine, tell your healthcare provider.

  • Your healthcare provider will tell you how much medicine to take and how often. Ensure you understand your doctor's instructions and take the medication exactly as prescribed.

What to do if you miss a dose of Leucovorin

  • This medicine needs to be given on a regular schedule. If you miss a dose, call your doctor for instructions.

Leucovorin contraindications - Who shouldn't take Leucovorin?

  • You should not use this medicine if you have had an allergic reaction to leucovorin.

  • Leucovorin should only be used for a specific type of anemia—megaloblastic anemia due to folic acid deficiency. It should not be used for any other types of anemia.

Leucovorin warnings

  • If you are pregnant or breastfeeding, talk to your doctor before taking this medicine.

  • Before taking this medicine, be sure to inform your doctor if you have anemia.

  • Keep all medicine out of the reach of children.

Leucovorin interactions & what to avoid when taking Leucovorin

  • Make sure your doctor is aware if you are also taking fluorouracil, phenobarbital, phenytoin (Dilantin), primidone (Mysoline), Bactrim (trimethoprim/sulfamethoxazole), or Septra (trimethoprim/sulfamethoxazole).

Leucovorin side effects - How does Leucovorin make you feel?

Serious Side Effects

  • Swelling in the lips, face, or tongue

  • Wheezing or trouble breathing

  • Skin rash, itching, or hives

If you  experience any of the side effects listed above, seek emergency medical attention immediately

Leucovorin News & Research

Leucovorin vs. folic acid: Differences and similarities explained

Leucovorin side effects and how to avoid them

Leucovorin for kids with autism

Colon cancer symptoms: What are the early signs of colon cancer?

Medically reviewed by Ashley Wong, Pharm. D.
Licensed Pharmacist

Ashley Wong, Pharm.D., has worked for healthcare companies where she translated complex drug information into easy-to-understand language for patients. She also served as a Senior Medical Information Specialist at a medical communications company, where she delivered clinically accurate drug information to healthcare providers and patients and compiled adverse event reports in accordance with the FDA's reporting guidelines.

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