What happens when someon takes schizophrenia pills without having this condition?

How bad is for the brain?

No medicine is without side effects and it all depends on what actually you have taken and in what quantities.
Common inconvenient side effects of all antipsychotic drugs used to treat schizophrenia include:

dry mouth
constipation
blurred vision
drowsiness
Some people experience sexual dysfunction or decreased sexual desire and menstrual changes.

Other common side effects relate to muscles and movement problems. These side effects include: restlessness, stiffness, tremors, muscle spasms, and one of the most unpleasant and serious side effects, a condition called tardive dyskinesia.

Neuroleptic Malignant Syndrome
This is a rare, but very serious, side effect. Signs to watch for are muscle stiffness that occurs over one to three days, a high fever, and confusion. If these symptoms occur, seek medical help immediately - take your relative to the emergency room if you cannot reach his doctor.

However i wouldnt emphasize their medications directly upon the brain, and if you have been taking these medica=tions regularly over a short period, perhaps you may have minimal complications.
In either case it is best to let your doctor examine you and to do what is best in your case. Most probably you will also need a few blood tests

how much have you taken? and why?
It depends what it is. Some doctors prescibe low doses of certain medications to help people who are not schizophrenic sleep. If it was a child who took it call the poison control center immediately. It is always risky when a person takes a medication that is not for them. It may interact with other medications that person is on or conditions that person has. As for how bad it is for the brain who knows. Probably not bad for the brain, but perhaps bad for something else depending on the dose and what it was. People work up to certain levels of medication so just taking it is not good for someone else. Not knowing anything abot what medication it is or anything about the person there is no way to tell. The best thing to do is call the local poison control and admit to it. It also depends how long ago this was. They will need the bottle and to know how much you took and what strength the tablets or capsules are. They need to know the time you took them and it you took them more than one time.

I will tell you and they will tell you not to take medication prescibed to another person. It is dangerous. It can hurt you it was not meant for you. You could die if you do this depending on what you take from people. Hopefully you are correct and it was just for schizophrenia and not something more dangerous.

Call poison control asap.
As crazy at this may sound, taking pills for mental disorders that you do not have can cause you to have them. For example, if you take xanax, which is for panic attacks and then stop taking them, your body gets use to them and will cause you to have panic attacks even if you didn't have them in the first place. Never take pills if you do not have the illness that they are prescribed for.
That is something I wonder, thanks for bringing that up on here you should get some pretty nice answers! It is also used for Bipolar so I do not know, the side effects of both Atypical and typical are kind of nasty so.