Leucovorin
Say it: loo-koh-VOR-in
Leucovorin is a form of the vitamin folic acid that protects healthy cells or helps some chemotherapy work better.
What it is
Leucovorin is a form of folic acid that the body can use right away. After high-dose methotrexate, it rescues healthy cells from harm. With fluorouracil, it helps the chemotherapy work better against cancer cells.
Often used for
- protecting healthy cells after high-dose methotrexate
- use with fluorouracil for colon and rectal cancer
- too much methotrexate or similar medicines in the body
- a type of anemia from low folic acid, when pills cannot be used
How you get it
It is given as a drip or shot into a vein, a shot into a muscle, or as pills. With fluorouracil it is usually a drip in clinic. After methotrexate, it is often given every few hours for a few days, and timing is very important. Your schedule may be different.
Common side effects and what helps
- Most side effects come from the chemotherapy it is given with. Leucovorin itself usually causes few problems.
- Diarrhea, when given with fluorouracil. Drink plenty of fluids and follow your team's diarrhea plan.
- Mouth sores, when given with fluorouracil. Rinse often with a salt and baking soda rinse.
- Nausea or throwing up. Ask your team about nausea medicine.
- Feeling tired. Rest when you need to.
- Rash or itching. Tell your team.
Call your care team right away if you have
- Diarrhea that does not stop, or 4 or more extra stools a day compared with your normal
- Mouth sores that make it hard to eat or drink
- A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher
- Signs of an allergic reaction, like a rash all over, swelling of the face or throat, or wheezing
- Throwing up so you cannot keep down your leucovorin pills or fluids
Before you start, tell your team
- If you have low vitamin B12 or pernicious anemia
- All medicines you take, including seizure medicines
- If you have kidney problems or fluid around your lungs or belly (if you get methotrexate)
- If you are pregnant, may become pregnant, or are breastfeeding
Good to know
- After high-dose methotrexate, leucovorin must be given on time. You will have blood tests to check methotrexate levels until it is cleared.
- Leucovorin can make side effects of fluorouracil stronger, especially diarrhea in older adults.
- It should not be used to treat anemia from low vitamin B12.
- Levoleucovorin is a closely related form. Your team will choose the right one.
At home
- If you take pills at home after methotrexate, take each dose at the exact time your team gave you. Set alarms.
- If you throw up a dose or miss a dose, call your team right away.
- Drink the amount of fluid your team tells you to.
- Store at room temperature, away from children.
Questions to ask
- Why do I need leucovorin with my treatment?
- If I take pills at home, what times should I take them?
- What should I do if I throw up a dose?
Part of these treatment plans
Side effect guides
Sources
Quick answers
- What is Leucovorin?
- Leucovorin is a form of the vitamin folic acid that protects healthy cells or helps some chemotherapy work better.
- What is Leucovorin used for?
- protecting healthy cells after high-dose methotrexate; use with fluorouracil for colon and rectal cancer; too much methotrexate or similar medicines in the body; a type of anemia from low folic acid, when pills cannot be used.
- How is Leucovorin given?
- It is given as a drip or shot into a vein, a shot into a muscle, or as pills. With fluorouracil it is usually a drip in clinic. After methotrexate, it is often given every few hours for a few days, and timing is very important. Your schedule may be different.
- What are the common side effects of Leucovorin?
- Most side effects come from the chemotherapy it is given with. Diarrhea, when given with fluorouracil. Mouth sores, when given with fluorouracil. Nausea or throwing up. Feeling tired. Rash or itching.
- When should I call my care team while taking Leucovorin?
- Diarrhea that does not stop, or 4 or more extra stools a day compared with your normal; Mouth sores that make it hard to eat or drink; A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher; Signs of an allergic reaction, like a rash all over, swelling of the face or throat, or wheezing; Throwing up so you cannot keep down your leucovorin pills or fluids.
- Which chemotherapy plans include Leucovorin?
- FLOT, FOLFIRI, FOLFIRINOX, FOLFOX, FOLFOXIRI, Hyper-CVAD.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.