This pain drug can cause sudden drop in blood pressure

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Acetaminophen, a well-known painkiller often used for headaches and fever, is typically taken in pill form. However, in hospitals, it is frequently given intravenously—directly into the bloodstream.

Intravenous (IV) delivery is preferred in certain cases because it works faster, allows precise control over dosage and timing, and is suitable for patients who cannot swallow pills. But this method comes with an unexpected side effect: a notable drop in blood pressure.

Research shows that around 60% of critically ill patients who receive IV acetaminophen experience this blood pressure drop, and about a third of these cases require medical intervention. Importantly, this effect is not limited to critically ill patients—it can occur in anyone receiving the medication intravenously.

Despite this risk, IV acetaminophen remains widely used in hospitals because it is generally safe and effective. A team led by Thomas Qvistgaard Jepps at the University of Copenhagen investigated why this drop in blood pressure happens.

They discovered that when the drug is given intravenously, it bypasses the liver—the organ that normally processes acetaminophen. This leads to the production of different chemicals in the body, which then interact with potassium channels. These channels play a key role in regulating blood pressure.

In laboratory tests on rats, Jepps’ team was able to block these potassium channels, significantly reducing the blood pressure-lowering effect of IV acetaminophen. This discovery could lead to safer ways of giving the drug in hospital settings.

For the general public, there is little reason for concern. When taken orally in recommended doses, acetaminophen does not significantly affect blood pressure.

The findings, published in the journal Atherosclerosis, Thrombosis, and Vascular Biology, provide valuable insight into how IV acetaminophen affects the body and could help improve its safety for patients who need it delivered this way.

If you care about blood pressure, please read studies that widely used blood pressure drug may increase eye disease risk and common blood pressure drugs linked to cognitive decline.

For more about blood pressure, please read studies about why checking blood pressure while lying down is very important and lowering top blood pressure number to less than 120 mm Hg effectively prevents heart disease.

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