The first-line psychiatric treatment for schizophrenia is antipsychotic medication, which can reduce the positive symptoms in about seven to fourteen days. However, medication fails to improve negative symptoms or problems in thinking significantly. Many antipsychotics are Dopamine antagonists (a substance interfering with how another substance works.) High concentrations of Dopamine are thought to be the cause of hallucinations and delusions. For this reason blocking Dopamine reception helps against hallucinations and delusions.