From the Guidelines
If you are on high doses of methotrexate, you should take at least 5 mg of folic acid per week, but not on the same day as your methotrexate dose, to minimize side effects and maximize the therapeutic effects of methotrexate. The specific dosage should be determined by your doctor based on your methotrexate dose and individual needs. Typically, patients on methotrexate take folic acid supplements to reduce side effects like nausea, mouth sores, and liver problems that methotrexate can cause. Methotrexate works by blocking folate metabolism, which is how it treats conditions like rheumatoid arthritis, psoriasis, or cancer. Taking folic acid helps replenish folate in your body's healthy cells without interfering with methotrexate's therapeutic effects.
Key Considerations
- The dosage of folic acid should be at least 5 mg per week, as recommended by the multinational evidence-based recommendations for the use of methotrexate in rheumatic disorders 1.
- Folic acid should not be taken on the same day as methotrexate to avoid reducing the medication's effectiveness.
- The timing and dosage of folic acid intake should be determined by your doctor based on your individual needs and methotrexate dose.
- Folic acid supplementation has been shown to reduce gastrointestinal and liver toxicity of methotrexate, without reducing efficacy 1.
Potential Side Effects
- Gastrointestinal side effects, such as nausea and mouth sores, can be reduced with folic acid supplementation.
- Liver toxicity can also be minimized with folic acid supplementation.
- It is essential to follow your doctor's specific instructions about timing and dosage to avoid reducing the medication's effectiveness.
Monitoring and Adjustments
- Regular monitoring of liver function, complete blood count, and other parameters is necessary to adjust the dosage of methotrexate and folic acid as needed.
- If you experience side effects from methotrexate, discuss with your doctor before adjusting your folic acid intake.
From the Research
Recommended Dosage of Folic Acid for Patients Taking High Doses of Methotrexate
- The recommended dosage of folic acid for patients taking high doses of methotrexate is not explicitly stated in the provided studies, but it is mentioned that folic acid dose at ≦5 mg/week has been recommended for rheumatoid arthritis (RA) patients to decrease the risk of methotrexate adverse effects 2.
- However, the study also found that the prevalence of methotrexate adverse effects was not significantly different between patients taking folic acid less and more than 5 mg/week 2.
- In the context of high-dose methotrexate, folinic acid is often used to mitigate side effects and reduce the incidence of systemic toxicity, and its dosage is guided by methotrexate concentrations and clinical improvement 3, 4.
- The use of high-dose folic acid is not well-studied, and its influence on methotrexate efficacies and safety is not clear, although one study found that higher doses of folic acid did not affect methotrexate efficacy in Japanese RA patients 2.
- Daily use of folic acid is recommended to ameliorate side effects in patients taking methotrexate, while folinic acid should only be used for methotrexate toxicity 5.
Folinic Acid Dosage for High-Dose Methotrexate Toxicity
- The required folinic acid dosage differs for low-dose and high-dose methotrexate toxicities, with early intravenous folinic acid administration recommended for high-dose methotrexate toxicities 4.
- The dose and duration of folinic acid are guided by methotrexate concentrations and clinical improvement 4.