Schizophrenia is one of the severe mental illnesses. The chances of the symptoms recurring are higher if treatment is abruptly stopped, even if the patient is feeling better. Treatment usually lasts for years. However depending on the improvement of the patient, the dose of medication can be reduced and he/she can be maintained on minimum effective dose.
You can compare it to
Diabetes or Hypertension. If you take the medications regularly then your Diabetes or blood pressure remains normal , if u stop medications it goes out of control and can lead to problems.
Similarly a person with schizophrenia can take medications regularly and maintain adequate functioning and be regular part of society.