Hello, Welcome to health care magic. I am Dr Alok Sinha, MD Psychiatry from India. I can understand your concern. I will try my best to answer your query. Tab Vicodin is a drug which has composition of Paracetamol 325 mg and Hydrocodone 10 mg. Hydrocodone is an opiod analgesic. Paracetamol is an aniline group of analgesic. This drug has a very high abuse potential because of its opiate content. The opiate in this drug produces a false sense of well being in patient; as a result he likes the effect of drug. With repeated use, mind gets used to the effects (as tolerance set in) and demands more and more quantity of medicine to achieve the desired effect. As a result individual develops a tendency to abuse the drug in more than prescribed quantity and frequency. Due to excessive intake of medicine high doses of paracetamol enters in to our body. High dose of Paracetamol is known for causing liver damage and peptic ulcer in upper GI tract. Due to regular use of few weeks the condition rapidly deteriorates, but it may not be known to patients. Generally peptic ulcer produces pain in abdomen, but due to analgesic property of this medicine, pain is not felt by patient while the disease progresses silently. Ultimately it may lead to Upper GI bleeding. This bleeding comes down in the form of Black tarry stool. This is happening with you. I suggest you to stop the medicine immediately and consult a gastroenterologist who may prescribe some investigations like upper GI endoscopy, liver function test, stool examination etc to confirm the diagnosis and treat you thereafter. I hope it answers your question. I wish you a better health.