Paracetamol is one of the most widely used over-the-counter medications we have and most of us probably use it for common things such as headaches, muscle aches, etc. Unlike anti-inflammatory medications which work directly at the site of pain by reducing inflammation, paracetamol acts on our brain and nervous system to reduce our perception of pain or the strength of the pain response in our brains.  

Given it works directly on our brains, it may not be surprising that if could have other effects on us as well, for example, impacting our emotional response to pain. In fact, previous research has found that paracetamol reduces emotional responses to things like their own social rejection and empathy for others' pain.  

New research looked at how paracetamol might impact people’s sense of fear, an emotion which is linked to pain, as it can keep us safe by making us more careful around potentially dangerous situations.  

To test this out, researchers gave participants either paracetamol or a placebo an hour before doing a task. Their task was to play a VR game called “Richie’s Plank Experience”. In this game people go up to the 80th floor of a skyscraper and walk as far as they can along a 2-metre plank. To make it even more real, the researchers got people to walk on an actual plank while playing the game. In the game itself you can jump off the plank and fly around the city putting out fires.  

The researchers measured a variety of characteristics indicative of fear and found that those people who took paracetamol:  

• Stepped onto the plank sooner  
• Walked across the plank faster  
• Had a smaller increase in heart rate while on the plank  

Interestingly, participants did not report dramatically lower fear levels when directly asked how frightened they felt. However, their behaviour and physiological responses suggested they were reacting less cautiously to the threatening situation.  

The researchers believe that paracetamol may influence brain regions involved in evaluating the significance of events. If dangers seem less threatening, fear responses may become weaker. This could explain why people on paracetamol moved more quickly and appeared less cautious when doing this task.  

The findings raise an important question: if paracetamol reduces fear-related caution, could it influence behaviour in real-world situations?  

Fear often serves a protective purpose. It encourages people to:  

• Slow down  
• Assess risks carefully  
• Avoid dangerous situations  
• Pay attention to threats  

If a medication reduces some of these protective responses, it could theoretically affect decisions in situations such as driving, operating machinery, working at heights etc.  

BUT – it's important to say not to stop using paracetamol based on the strengths of this one study! Nor should people try and use more as a way of self-medicating, as there are considerable dangers in overusing paracetamol, particularly liver damage.  

However, it is interesting to be aware that side effects of a common medication could be much wider than we initially think and it’s good to understand these.  

Here’s the reference in case anyone is interested: Behavioural consequences of blunting fear with acetaminophen. Emotion, 26(6), 1315–1322. 

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