what is the main problem with taking an overdose of paracetamol?

hepatotoxicity

it occurs when there is insufficient amount of glucoronate or sulphate to be added which allows it to be secreted out through the urine and inactivates it, when glucoronate or sulphate is unavailable it means that toxic metabolites are formed these can then go on to cause hepatic necrosis.

how do NSAIDs work to reduce pain? this is known as the analgesic affect

NSAIDs work to prevent prostaglandin production and so they prevent sensitisation to pain producing compounds as prostaglandins are what sensitise histamine and bradykinin to nocioceptive nerves which allows them to produce a painful stimulus when these compounds are detected

how do NSAIDs work? this is known as the anti-pyretic affect

they act to prevent the formation of prostaglandins and prevent the rise in body temperature.

they have no effect on normal body temperature because they only target prostaglandin formation which only act to increase above th enormal temperature

what causes a fever to occur?

interleuken 1 which causes prostaglandin production in the hypothalamus which causes an increased thermostat set point (inc in body temp) interleukin 1 is released by macrophages in response to detection of bacterial endotoxins