Acetaminophen, widely known for easing headaches, fevers, and mild pain, is a medicine most people recognize. In everyday life, it’s usually taken as a pill and is considered safe when used as directed. But in hospitals, the drug is sometimes given in a different way—intravenously, or directly into the bloodstream.
This method is helpful for patients who can’t swallow pills or who need fast, controlled pain relief. But new research has uncovered an unexpected side effect when acetaminophen is given through an IV: a noticeable drop in blood pressure.
This reaction isn’t limited to people who are seriously ill. While it is more common in intensive care units, it can happen to anyone receiving acetaminophen through an IV. In fact, studies show that nearly 60% of severely ill patients who were given IV acetaminophen experienced a drop in blood pressure. Of those, one-third needed medical help to bring their pressure back up.
The research was led by Thomas Qvistgaard Jepps and his team at the University of Copenhagen. They wanted to understand why this drop happens and found something interesting.
Normally, when you swallow acetaminophen, it goes through the liver before entering the bloodstream. But when the drug is given directly into a vein, it bypasses the liver, which changes how the body reacts to it.
The researchers discovered that IV acetaminophen affects potassium channels—tiny gateways in blood vessel cells that help regulate blood pressure. These channels open and close to control how wide or narrow blood vessels become. If the channels open too much, blood vessels widen, and blood pressure drops.
In experiments with rats, Jepps’ team blocked these potassium channels to stop the sudden drop in blood pressure caused by IV acetaminophen. The results were promising, suggesting that targeting these channels could help prevent this side effect in hospital patients.
This finding is especially important during times when IV acetaminophen use increases, such as during the COVID-19 pandemic, when many critically ill patients needed fast and effective pain management. Understanding how the drug affects the body in different forms can help doctors make safer choices for their patients.
For most people who take acetaminophen by mouth, this isn’t something to worry about. The pill form is processed through the liver first, so it doesn’t cause the same changes in blood pressure. But the study is a good reminder that the way a drug is given can have a big impact on how it works—and on the side effects it might cause.
Published in the journal Atherosclerosis, Thrombosis, and Vascular Biology, this research offers important insights for healthcare workers. It highlights the need for closer monitoring of blood pressure in patients receiving IV acetaminophen and could lead to new ways to protect patients from unexpected drops in blood pressure.
In summary, this study sheds light on a less-known risk of IV acetaminophen and offers a path toward safer treatment options in hospitals—especially for those in critical care.
If you care about high blood pressure, please read studies about breakfast for better blood pressure management, and the gut feeling that lowers blood pressure.
For more health information, please see recent studies about how the dash diet helps lower blood pressure, and how to eat your way to healthy blood pressure.
Copyright © 2025 Knowridge Science Report. All rights reserved.
