How much was taken? If it was not a prescription dosage or prescribed for you i would go to a doctor/ER as soon as possible even immediately if you are experiencing any unusual symptoms. I am not sure what the symptoms of Prolixin are, maybe try Googling them. but if you experiences any shortness of breath, fast heart beat, confusion, weakness, shakiness please seek immediate doctor/hospital treatment. if you are worried about it please also see a doctor as i am not a doctor or medical person at all this is just my option.
Taking medication accidentally can quite serious it all depends how much it taken and the person taking it and what is that is taken so any worries at all it is better to be safe than sorry.
CALL YOUR PHARMACIST OR DOCTOR!!!