Can I cut a Seroquel XR tablet in half? Why?

I wouldn't do it, I did it last night, per my doctor's advice and I believe that I had a seizure. I spoke to the pharmacist and he advised me not to do it again. Some doctors don't know. I always listen to a pharmacist over a Dr when it comes to these questions.

Unless the tablet is scored for easy splitting you just shouldn't do it because you have no idea how much or how little of the drug may be in each half.
Scored tablets are manufactured so that equal amounts of the active ingredient are delivered and unscored tablets are not.
There are very good reasons why the warning not to break tablets is posted on the Patient Information sheet that comes with your prescription.
But if you don't care... go ahead and take your chances.

I did it once and it was horrible. My doctor for some reason thinks that pills like this can be cut so that part of it releases right away and the coating prevents the other part from releasing until later. At least with me, that was not the case. I felt very sedated for a couple of hours which was nice because I had been trying to taper off of it but when that wore off I felt even more awful and went back into withdrawal. Every other doctor I consulted said that this was a terrible idea and advised me never to cut one again. I told my doctor and we agreed not to do this again. So no, I do not recommend cutting any extended release pills. Seroquel XR is also on the list of pills never to cut. It just turns it into a very sudden release of all of the medication meant for a 24 hour period at once.

I use Seraquel XL 200mg. and cut them in half all the time, because 200mg is just too much for me. I have had no ill effects at all!

any medication that has XR (extended release) is not meant to be altered in any way shape form or fashion, the drug is meant to release an amount over a 24 hour period of time if you half the pill crush or chew it can cause a big dose of this medication to enter your system and possibly cause you to experience an overdose. it's given this way so you have a stable amount of medicine throughout the day and nightime hours until your next dose, Please follow the directions exactly as prescribed on the bottle, your doctor has determined this is the best way to give your medication and in order for you to be safe always take it at the same time each day, as it probably says on the bottle don't half the pill, don't crush it, or alter it in any way. We all want you to be safe and to be the best that you can possibly be.

I take Seroquel XR (quetiapine).

"Do not break, crush, or chew the medication. Doing so can destroy the long action of the drug and may increase side effects".

All the best.-