It probably isn't recommended to take LSD before an exam, unless you want to fail it. Generally speaking, LSD is a hallucinogenic drug that interrupts your thought process. If you've ever take LSD and felt like your brain was firing at a superhuman pace, try reading a book while high before you commit to failing an exam.
Although, everyone does react to drugs differently and LSD may end up helping you ace the test. Still wouldn't try it, though.
I would definitely not recommend taking an exam while under the influence of LSD. LSD is a very dangerous drug and I would not recommend taking it all. If you were to take LSD though, make sure you are in a safe place with trusted friends and you have a plan in case you experience panic attacks due to the drug.
There is no evidence that LSD would help you in an exam and it would most likely cause you to perform very badly on an exam. LSD will alter your state of mind and likely not in a way that will help you in any way.
