How Folic Acid interacts with Trimethoprim-containing antibiotics

Interaction type: Depletions

Interaction rating: Study Supported

Trimethoprim slightly interrupts the breakdown of folic acid in the body. Supplementation with the affected nutrient may be necessary. (1)

These drugs include trimethoprim (TMP), trimethoprim and sulfamethoxazole (TMP-SMZ), trimetrexate glucuronate


  1. Kahn SB, et al. Effects of Trimethoprim on Folate Metabolism in Man. Clin Pharmacol Ther. Oct1968;9(5):550-60.