Undiagnosed megaloblastic anaemia, folate dependent tumors; pregnancy. Monitor calcium levels in patients receiving combined 5-Fluorouracil/Folinic acid treatment. To be given parenterally in the presence of GI toxicity, nausea or vomiting. Monitor serum levels of methotrexate to determine the optimal dose and duration of folinic acid admin. Monitor CBC, electrolytes and liver function tests before and regularly during treatment.

Fluorouracil: Folinic acid may increase the toxicity associated with fluorouracil if the two are administered together. Some adverse effects that have occurred, particularly in elderly patients, include severe enterocolitis, diarrhea, and dehydration. Sulfamethoxazole-trimethoprim: A potential drug interaction exists with concomitant use of sulfamethoxazole-trimethoprim and folinic acid. Folinic acid has been shown to decrease the efficacy of sulfamethoxazole-trimethoprim in the treatment of pneumocystis carinii, a common cause of pneumonia in AIDs patients