Several studies indicate that taking caffeine and acetaminophen together could be very dangerous. There is a risk of substantial liver damage when you mix these two substances together. Many people take acetaminophen, which is a popular pain reliever, and wash it down with coffee or soda. When this is done regularly, it could result in scarring of the tissue inside the liver. This could lead to liver failure in some people, particularly for those who already have liver diseases such as hepatitis.
There is also some reason for concern regarding medications containing both caffeine and acetaminophen. Many manufacturers of over-the-counter pain-relieving medicines combine the two ingredients together into each pill because the caffeine can increase the effectiveness of the acetaminophen. Over-the-counter medicines for treating menstrual cramps are one example of pain relievers that contain both ingredients. If you regularly take acetaminophen that additionally contains caffeine, you may want to be careful not to wash the pills down with coffee, soda, or any other drink containing substantial amounts of caffeine.
In general, caffeine and acetaminophen should not cause you any major problems when mixed together if you have no liver issues and you take only the recommended dosage of the medication. People with chronic liver problems may be at risk for further liver damage even if they take less than the recommended dosage of acetaminophen combined with caffeine. Unfortunately, many people without liver damage end up having it because they took too much acetaminophen combined with caffeine over a long period of time. Lots of people end up in the emergency room with liver toxicity problems resulting from overdoses of acetaminophen.
When a person's body breaks down acetaminophen, it produces a by-product that is toxic. Combining caffeine and acetaminophen together results in the production of this by-product increasing to three times as much as it would without the addition of caffeine. Scientists were able to confirm this by performing a test on E. coli bacteria. They believe that the impact of caffeine and acetaminophen on the bacteria would be similar in humans, but there is still a need for further testing.
Even if you do not have liver damage, it may be best for you to avoid taking your acetaminophen with caffeine. If you must combine your acetaminophen with caffeine, you should probably take special care not to take more than the recommended dosage. In the event that you have liver damage or some other disease that affects your liver, it would likely be best to avoid combining caffeine with acetaminophen altogether.