Leucovorin comes in intravenous (IV), intramuscular (IM) injection
(shot), and oral form.
How It Works
Leucovorin is a derivative of folic acid. Leucovorin works
differently depending on whether it is used with
methotrexate (MTX) or
Methotrexate: Leucovorin is given to "rescue"
the gastrointestinal lining and bone marrow cells from MTX toxicity. Most of
the complications and side effects of methotrexate can be either prevented or
treated by using leucovorin, which is usually given 24 hours after
Fluorouracil: Leucovorin increases the effectiveness
of 5-FU, increasing the anticancer effect.
Why It Is Used
Leucovorin is used with either methotrexate (MTX) for the treatment
ectopic pregnancy or fluorouracil (5-FU) for cancer treatment.
How Well It Works
Most of the complications and side effects of methotrexate can be
either prevented or treated by using leucovorin, which is usually given 24
hours after the methotrexate is given.
Leucovorin enhances the binding of fluorouracil (5-FU) and prolongs
the life span of 5-FU, increasing the anticancer effect.1
Leucovorin is very well tolerated and has almost no side effects of
See Drug Reference for a full list of side effects. (Drug Reference
is not available in all systems.)
What To Think About
Leucovorin generally decreases the severity of side effects of MTX.
It can increase the severity of the side effects of 5-FU when used with that
Leucovorin should be administered only under the supervision of a
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Meyerhardt JA, Mayer RJ (2005). Systemic therapy for
colorectal cancer. New England Journal of Medicine,