What are the side effects of drinking alcohol while taking warfarin?

Daily alcohol use while using warfarin increases the risk for stomach bleeding and may limit the drug's effectiveness, according to RxList. While alcohol consumption may or may not produce adverse effects, heavy usage may cause patients to bleed more easily, and the medication interaction is classified as moderate, states Drugs.com.

Prior to using warfarin, patients should limit their alcohol consumption and ask their doctor or pharmacist how much alcohol they may safely drink, advises RxList. Those using alcohol are encouraged to contact their physician promptly at the presence of bleeding or bruising, vomiting, blood in the urine or stools, headache, dizziness, and weakness.