Empathy is directly tied to the ratio between estrogen and testosterone in the body. (Yes, this is a grossly simplified statement, it's eli5 not eliamdoingmydissertstion.) Any drug that affects brain chemistry or blocks receptors in the brain (which paracetamol does) also alters the way the brain uses hormones like testosterone and estrogen, which then can affect mood, empathy, etc. by changing that ratio or changing the brain's perception of that ratio. (For example, the brain may have the same amount of estrogen, but if it can't absorb it out of the blood then it percieves that there is less, etc.)