Acetaminophen is the generic name for the brand drug Tylenol. While there are some 137 drugs known to have some interaction with acetaminophen, many of these are minor effects. In addition, some referenced drugs are no longer commonly prescribed. This article will focus on the six major drugs, or drug categories, that can have serious side effects if combined with acetaminophen.
Alcohol and Chlestyramine Interactions
Although commonly thought of as a beverage, alcohol in large quantities acts as a drug in the human body. Many cough and cold preparations also contain alcohol. If consumed in high volume or chronic amounts, alcohol and acetaminophen will increase the risk that a patient will develop hepatotoxicity, which means liver damage. In extreme cases, complete liver failure has been known to occur.
Cholestyramine (brand name Questran) is prescribed as a cholesterol-lowering agent. Cholestyramine decreases the body’s absorption of acetaminophen in the gastrointestinal tract. Clinically, this means that a patient should not take acetaminophen and cholestyramine at the same time; ideally, the two drugs should be taken at least two hours apart.
Isoniazid and Warfarin Interactions
Isoniazid, more commonly known as the brand drug INH, is a drug prescribed to patients as a prophylaxis for TB. Concurrent consumption of isoniazid plus acetaminophen can cause nausea, vomiting, abdominal discomfort, or fatigue. In severe cases, the combination can again cause liver damage.
Warfarin (Coumadin) is the most commonly prescribed anticoagulant, or blood thinner, in the U.S. If a patient is on both acetaminophen and warfarin, there is likely to be a magnified anticoagulation effect. Therefore, he/she should have frequent lab monitoring of his/her anticoagulant levels, and the warfarin dose may need to be adjusted downward. Of course, the prescribing physician should closely manage this process. Non-adherence to this rule may lead to serious complications, such as stroke or gastrointestinal bleed.
Diflunisal Interactions
Diflunisal (Dolobid) is a non-steroidal anti-inflammatory (NSAID) drug that is used to treat chronic pain patients, such as those with osteoarthritis or rheumatism. It has been noted to increase blood levels of acetaminophen by as much as 50%. This means that any patient on acetaminophen and diflunisal should be closely monitored for signs of *acetaminophen overdose. Another viable option would be for the physician to switch the patient from diflunisal to an alternate NSAID medication.