Brief Answer:
it is commonly used for mental disorders

Detailed Answer:
Hi

Thanks for your query.

Thorazine (chlorpromazine) is used for - the treatment of schizophrenia (mental illness), to control nausea and vomiting and for relief of intractable hiccups.

Some of potential serious side effects may be -
twitching or uncontrollable movements of eyes, lips, tongue, face, arms, or legs; tremor (uncontrolled shaking), drooling, trouble swallowing, problems with balance or walking;
feeling restless, jittery, or agitated;
seizure (black-out or convulsions);
nausea, upper stomach pain, itching, and jaundice (yellowing of the skin or eyes);
high fever, stiff muscles, confusion, sweating, fast or uneven heartbeats, rapid breathing
unusual thoughts or behavior;
slow heart rate, weak pulse, fainting, slow breathing

Because of all of these and availability of safer drugs, its use has declined now.

However, as he has taken it long back, it should not cause any problems now.

Hope I have answered your query. I will be available to answer further followup queries, if any.

---