Folic acid is often prescribed alongside methotrexate for several reasons:

1. Reducing Side Effects: Methotrexate, a medication used in various conditions like rheumatoid arthritis, psoriasis, and some cancers, can deplete folic acid levels in the body. Folic acid supplementation helps counteract this depletion and decrease the risk of certain side effects associated with methotrexate, such as mouth sores, nausea, hair loss, and gastrointestinal issues.

2. Preserving Healthy Cells: Methotrexate works by blocking certain enzymes involved in cell division, including cancer cells. However, it can also affect the replication of healthy cells. Folic acid is vital for cell division and DNA synthesis. Supplementing with folic acid helps maintain the necessary levels for healthy cell function while allowing methotrexate to target the diseased cells.

3. Balancing Effects: The administration of folic acid alongside methotrexate aims to balance the drug's therapeutic effects on the targeted cells with the maintenance of healthy cells. This balance helps in reducing the severity of methotrexate's side effects while preserving its effectiveness in treating the intended condition.

The prescribed dosage and timing of folic acid supplementation in relation to methotrexate intake are typically managed by healthcare providers to ensure that the beneficial effects of methotrexate are not compromised while minimizing its potential side effects.