Find patient medical information for Coumadin oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. COUMADIN (crystalline warfarin sodium) is an anticoagulant which acts by inhibiting vitamin K-dependent coagulation factors. Chemically, it is 3-(α-acetonylbenzyl)-4-hydroxycoumarin and is a racemic mixture of the R - and S-enantiomers. Crystalline warfarin sodium is an isopropanol clathrate. The crystallization of warfarin sodium virtually. Now costly and time-consuming trips to your doctor's office or lab for Coumadin® checks are a thing of the past. Call 888-577-6846 for more information Coumadin Side Effects. Generic name: warfarin Medically reviewed by Drugs.com. Last updated on May 8, 2021. Consumer; Professional; Note: This document contains side effect information about warfarin. Some of the dosage forms listed on this page may not apply to the brand name Coumadin. For the Consumer.