A recent study from the University of Copenhagen has discovered why acetaminophen (also known as paracetamol), a widely used painkiller for headaches, can cause a significant drop in blood pressure when given through an IV (intravenous).
Acetaminophen is a popular pain reliever that most people take in pill form. However, in hospitals, doctors often administer it directly into the bloodstream through an IV. This method is used for critically ill patients who cannot swallow pills. It also allows faster pain relief and gives doctors more control over the dose and timing.
Despite these benefits, IV acetaminophen has a serious side effect—it can cause a temporary but sharp drop in blood pressure. Previous studies have shown that this effect is quite strong, and it happens in both regular hospital patients and critically ill individuals.
Among the most severely ill patients, 6 out of 10 have experienced this side effect. For about one-third of these patients, the drop in blood pressure was so severe that they needed medical intervention to stabilize their condition.
In this study, researchers wanted to understand why this happens. They found that the way the drug is processed in the body changes depending on whether it is taken orally or through an IV.
When people take acetaminophen as a pill, it passes through the liver before spreading through the bloodstream. However, IV acetaminophen bypasses the liver, meaning it is broken down differently.
Once in the bloodstream, the breakdown products of the drug affect potassium channels, which help control how blood vessels tighten and relax. This means that when potassium channels are affected, blood pressure drops sharply.
To confirm this, the researchers gave test rats a drug that blocked these potassium channels. When they did this, the large drop in blood pressure was significantly reduced. This suggests that blocking potassium channels may be a way to prevent this side effect in patients receiving IV acetaminophen.
Despite this discovery, the researchers emphasize that most people do not need to worry about taking acetaminophen in pill form as long as they follow the recommended dose. However, this study is especially important because, during the COVID-19 pandemic, more critically ill patients have been receiving IV acetaminophen in hospitals to manage pain and fever.
Understanding how this painkiller affects blood pressure could help doctors make better decisions about its use in vulnerable patients.
The study, led by Thomas Qvistgaard Jepps and his team, was published in Atherosclerosis, Thrombosis, and Vascular Biology.
If you care about high blood pressure, please read studies about unhealthy habits that may increase high blood pressure risk, and drinking green tea could help lower blood pressure.
For more information about high blood pressure, please see recent studies about what to eat or to avoid for high blood pressure, and 12 foods that lower blood pressure.
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