Caution is recommended in patients with a history of bipolar illness. Mood elevation is possible in this population.
Caution is also recommended in patients taking anticonvulsant medications as folate may interfere with anticonvulsant medication, and may lower seizure threshold. Furthermore, it has been reported that anticonvulsant medications interfere with folate metabolism, but the exact action is unclear; therefore caution is recommended with patients in this therapeutic group.
Folinic acid may enhance the toxicity of fluorouracil. Deaths from severe enterocolitis, diarrhea, and dehydration have been reported in elderly patients receiving weekly formyl-THF and fluorouracil. Concomitant granulocytopenia and fever were present in some but not all of the patients. The concomitant use of formyl-THF with trimethoprim- sulfamethoxazole for the acute treatment of Pneumocystis carinii pneumonia in patients with HIV infection was associated with increased rates of treatment failure and mortality in a placebo controlled study.13
Patients undergoing cancer treatment should consult their licensed medical practitioner for advice.