Acetaminophen is a medicine that many people around the world use to ease pain or bring down a fever.
You might have taken it yourself if you had a headache, sore muscles, or the flu. It’s sold under many brand names and is easy to find in pharmacies and supermarkets.
Most of the time, people take it by mouth in the form of pills or capsules. When used properly, it is seen as a safe and fast way to feel better.
In hospitals, however, doctors sometimes give acetaminophen in a different way. Instead of giving a tablet, they deliver the medicine directly into the patient’s blood through a needle.
This is called an IV, or intravenous, injection. This method works faster and is very useful for people who cannot swallow, such as patients who are very ill or unconscious. It also helps doctors give a very exact dose.
But a new study from the University of Copenhagen has found something unexpected. When acetaminophen is given through an IV, it can cause a sudden drop in blood pressure. This side effect can be risky for patients who are already seriously ill.
The researchers looked at how often this happened and found that about 60% of very sick patients had lower blood pressure after getting the medicine through an IV. Even more concerning, about one-third of those patients needed emergency help to fix the problem.
The study was led by Thomas Qvistgaard Jepps and his team. They wanted to find out why this blood pressure drop happens. They discovered that when acetaminophen goes straight into the bloodstream, it skips the liver.
Normally, the liver helps break down the medicine. But without the liver’s help, the body creates different substances after processing the drug.
Some of these substances can change how tiny parts of the blood vessels—called potassium channels—work. These channels help blood vessels stay at the right size. When they are affected, the blood vessels can open too wide. This makes the blood pressure drop quickly.
To test this, the team did experiments on lab rats. They gave the rats IV acetaminophen, and the rats’ blood pressure dropped. But when they blocked the potassium channels, the blood pressure stayed normal. This showed that the potassium channels play a big role in this side effect.
If you take acetaminophen at home in pill form and follow the directions, you don’t need to worry. This blood pressure problem mostly affects people in hospitals who are getting high doses through an IV.
For doctors and nurses, though, this study is very helpful. It explains why some patients suddenly have low blood pressure and could lead to safer ways to give the medicine.
This research is especially important in times like the COVID-19 pandemic, when many people are treated in hospitals. Understanding how common drugs affect the body can help medical workers give better care and save lives.
The full study is published in the journal Atherosclerosis, Thrombosis, and Vascular Biology.
If you care about blood pressure, please read studies about This alcohol treatment could help treat high blood pressure and How blood pressure changes with age.
For more about blood pressure, please read studies about Intensive blood pressure treatment for older adults may harm heart and kidneys and What you should know about high blood pressure medications.
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