How to treat paranoia?

Depends on the cause: Paranoia is a symptom which, like most symptoms, can have multiple causes, so treatment depends on identifying the cause. Severe paranoia can be caused by schizophrenia but paranoia can also be caused by bipolar disorder, anxiety, personality disorders, alzheimer's disease, hyperthyroidism, infections & reactions to a wide variety of both prescription and non-prescription drugs. Please see comment.

Have an: Evaluation by your family doctor to rule out any underlying medical issues and then see a psychiatrist. Paranoia is only a symptom that can occur in a number of illnesses. Treatment depends on the illness that is causing this symptom.

Psychotherapy & meds: Typically psychotherapy and medication are the best approaches. Depending on symptom severity, I would recommend psychoanalysis.

See a therapist: "Paranoia" is a specific symptom, usually associated with psychotic disorders. The term is often used in common conversation to refer to all kinds of fears, anxieties, suspiciousness, etc. If it is bothering you it could be worth at least consulting with a therapist to put your mind at ease and get a better handle on exactly where these feelings are coming from.

Paranoia: SInce paranoia is often very deeply rooted, the most in-depth treatments are psychodynamic psychotherapy or psychoanalysis.