Acetaminophen, more commonly known as Tylenol, is one of the most popular over-the-counter pain medications we encounter. Popping a couple Tylenol pills when you have a headache is as routine as brushing your teeth before you go to bed. But based on recent research, acetaminophen’s short- and long-term side effects may involve more than potential liver damage. Here are seven effects of acetaminophen that researchers have studied in recent years, and which call into question the safety and efficacy of the drug.

Reduces Empathy

Acetaminophen may alleviate your splitting headache, but it may also numb your emotions, according to researchers at Ohio State University. In a recent study, Baldwin Way, assistant professor of psychology at Ohio State, and his team investigated how acetaminophen could actually reduce people’s ability to feel both negative and positive feelings. When students were divided into an acetaminophen group and a placebo group, those who had taken the drug showed less empathy when rating sad short stories compared to those who hadn’t.

“If you are having an argument with your spouse and you just took acetaminophen, this research suggests you might be less understanding of what you did to hurt your spouse’s feelings,” Way said. He and his team have examined this trend for some time, and found similar results in a 2015 study. However, they still don’t completely understand the emotional or psychological mechanisms behind the drug’s ability to reduce empathy. Way hypothesizes that there’s a possibility acetaminophen blunts a part of the brain called the insula, which registers and responds to emotional pain.

Kills Hundreds of Americans Every Year

Tylenol may seem like a safe drug, and for the most part it is. But long-term use of the pills, or taking one too many in a short period of time, may contribute to liver damage and even death from overdose. According to a ProPublica analysis of three sets of data, up to 980 people die each year of causes related to acetaminophen use, and over 300 die from direct acetaminophen overdose. The same report found that based on FDA data, the number of deaths caused by acetaminophen was increasing faster than those for other common pain medications like aspirin and ibuprofen. There’s a fine line between safety and risk when it comes to acetaminophen, and the recent stats prove that: taking the right dose, not more, is important.

Affects Your Brain’s Ability To Process Errors

It’s only been recently that scientists have begun investigating acetaminophen’s effect on the brain and behavior. The research that showed that the drug could dull emotions became something of a trigger for other scientists to delve further into understanding exactly how it affects pathways in the brain.

As a result, earlier this year, researchers published a study that found acetaminophen actually impaired people’s ability to detect errors, hinting that not only does it blunt feelings, but it may also mess with your problem-solving ability. “It looks like acetaminophen makes it harder to recognize an error, which may have implications for cognitive control in daily life,” author of the study Dan Randles said.

Makes You Less Existential

This all comes back to the same notion: that acetaminophen may affect the brain in more ways than we originally thought. Researchers are aware that brain pathways managing physical pain are linked to emotional responses, and believe that acetaminophen’s subtle effects on our emotions may be related to that. In 2009, researchers found that the drug could reduce feelings of social rejection and existential distress.

“When people feel overwhelmed with uncertainty in life or distressed by a lack of purpose, what they’re feeling may actually be painful distress,” the researchers stated. “We think that Tylenol is blocking existential unease in the same way it prevents pain, because a similar neurological process is responsible for both types of distress.”

Lowers Testosterone In Unborn Babies

Generally speaking, acetaminophen is safe to take in the form of Tylenol if you’re pregnant — and taking the right dose. But recent research questions the drug’s safety when it comes to the unborn baby. For example, a 2015 study discovered that acetaminophen was linked to lower testosterone in male infant mice. Since the study was only done in mice, there’s nothing to worry about if you take occasional Tylenol pills while pregnant, but the researchers still encourage pregnant women to talk to their doctors first.

Might Give Your Kids ADHD

Another recent study found that mothers who used Tylenol to treat fevers while they were pregnant reported more ADHD-like symptoms in their children. But the researchers were unable to fully conclude whether taking Tylenol during pregnancy was to blame more than other factors for the increased risk of ADHD symptoms within some children. Instead, the researchers note that mothers who take regular doses of Tylenol — especially to reduce fevers — should be totally fine, assuming they’re living a healthy lifestyle.

Doesn’t Always Work For Back Pain

Perhaps one of the most surprising discoveries about acetaminophen is that it’s not exactly the most effective medicine for back or neck pain. In 2014, a group of Australian researchers found that acetaminophen did nearly nothing to help treat back pain, though it did still prove useful for headaches, toothaches, and other types of pain. Another study came to a similar conclusion, noting that doctors should reconsider recommendations to use Tylenol for back pain or even osteoarthritis in certain joints, like the hip and knee. However, don’t be afraid to continue using safe doses of acetaminophen to treat pain and fever.