Maximum Daily Dose of Chlorpromazine (Thorazine)
The maximum daily dose of chlorpromazine is 2,000 mg per day, though doses exceeding 1,000 mg per day for extended periods rarely provide additional therapeutic benefit. 1
Dosing Framework by Clinical Context
Hospitalized Patients with Acute Psychosis
- Initial approach: Start with intramuscular chlorpromazine until the patient is controlled, then transition to oral dosing 1
- Standard effective dose: 500 mg per day is generally sufficient for most hospitalized patients 1
- Upper dosing range: Gradual increases to 2,000 mg per day may be necessary in some cases 1
- Practical ceiling: There is usually little therapeutic gain achieved by exceeding 1,000 mg per day for extended periods 1
- Discharged mental patients: Daily doses of 800 mg are not uncommon in this population 1
Outpatients and Less Acute Presentations
- Mild cases: 10 mg three times daily or four times daily, or 25 mg twice or three times daily 1
- More severe outpatient cases: 25 mg three times daily initially, then increase by 20-50 mg at semi-weekly intervals until the patient becomes calm and cooperative 1
- Typical maintenance: 400 mg daily is the usual effective dose for less acutely disturbed patients 1
Special Populations Requiring Lower Doses
- Elderly patients: Dosages in the lower range are sufficient, as they are more susceptible to hypotension and neuromuscular reactions 1
- Debilitated or emaciated patients: Increase dosage more gradually in these populations 1
- Pediatric patients (6 months to 12 years): Maximum 500 mg per day for severe behavior disorders; little evidence supports doses beyond this in severely disturbed mentally retarded patients 1
Evidence Quality and Clinical Context
The FDA label provides the most authoritative guidance on maximum dosing 1. Research evidence from a Cochrane review examining chlorpromazine dosing found that medium doses (401-800 mg/day) caused significantly more extrapyramidal symptoms than low doses (≤400 mg/day) without clear additional benefit for global or mental state outcomes 2. High doses (>800 mg/day) showed some benefit for global state improvement but resulted in significantly more people leaving studies due to side effects and markedly increased extrapyramidal symptoms 2.
Critical Safety Considerations
Common pitfall: Exceeding 1,000 mg per day for extended periods without documented therapeutic benefit exposes patients to unnecessary risk of extrapyramidal symptoms, hypotension, and other adverse effects 1, 2.
Monitoring imperative: When using doses in the upper range, observe closely for hypotension and neuromuscular reactions, particularly in elderly patients 1.
Titration strategy: Increase dosage gradually until symptoms are controlled, then reduce to the lowest effective maintenance level after symptoms have been controlled for a reasonable period 1.