How long does it take for paracetamol to have cleared enough for it to not show up in blood tests?

A friend of mine took 18 200mg paracetamol tablets. 6 hours later, there was none showing in her blood tests. Does it clear this quickly? The reason I ask is she may have been lying about taking them, or taking that amount. Does anyone know?

Thanks
Rach

i don't know the exact clearance time on tylenol,but can tell you that if she took that many,it would have had to have actually shown up in any blood test that was ordered to actually look for it.it all has to metabolize thru the liver.considering the max daily dose intake is at 4000mgs,while she would have been within that 'safe' limit for DAILY intake,taking it all at one time would have had to take more than six hours just to actually get it metabolized and sent into the bloodstream,and then have it actually excreted out of the body.thats alot of tylenol to hit the liver with all at one time.it most definitely would have been considered an "overdose" and would have been treated that way.i have a feeling your friend is not telling you the whole story.JMO. FB