I agree with the above statement. While someone who is Clairvoyant may become confused, I highly doubt your friend is one. As you said he is being harmed and he himself calls them hallucinations, and it would be much safer for the both of you to simply take him to the doctor - and if you cannot, then it would be healthy for you to stop worrying over someone who should want to keep themselves healthy and their friends worry free.
Majick is to be used only as a last resort, and it is never to be used as an all around problem solver. Using majick without the person's consent is also very bad not to mention dangerous, and with all of that said...safety is always priority. Your own and His.
I'm in the medical field you friend has a severe mental illness, your friend need to seek immediate medical health and or a mental health evaluation due to this person having hallucinations this serious risk if your friend doesn't seek emergency room help or a doctor
Magic is not an option nor can it ever be.
He has a serious mental illness