Perphenazine
Generic: perphenazine · Brand: Trilafon® · Class: 1st Generation Antipsychotic (Mid Potency)
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How It Works
Perphenazine is a first-generation (typical) mid-potency antipsychotic in the phenothiazine class. It blocks dopamine D2 receptors to reduce psychotic symptoms, and also has antihistamine and anticholinergic properties contributing to sedation and other side effects. As a mid-potency agent, it has fewer movement side effects than high-potency agents like haloperidol, but more sedation and anticholinergic effects. It gained renewed attention from the landmark CATIE trial, which found it performed comparably to several second-generation antipsychotics with a generally favorable tolerability profile.
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What It Treats
SchizophreniaFDA-approved; shown in the CATIE trial to be comparable to many second-generation antipsychotics
Severe Nausea and VomitingFDA-approved for intractable nausea and vomiting
Psychotic DisordersUsed for various psychotic conditions as an affordable and effective option
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Dosing Overview
| Population | Start | Typical Range | Max |
|---|---|---|---|
| Adults Schizophrenia | 4–8 mg 3x daily | 8–16 mg 2–4x daily | 64 mg/day |
| Adults Nausea (oral) | 4 mg 3–4x daily | 8–16 mg/day | 24 mg/day |
| Older Adults Start low | 2–4 mg/day | 4–8 mg/day | 32 mg/day |
Taken 2–4 times daily with or without food. One of the more affordable first-generation antipsychotics. Mid-potency profile means a balance between EPS risk and sedation.
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Side Effects
Common
- Sedation
- Dry mouth
- Constipation
- Blurred vision
- Dizziness
- Weight gain
- Muscle stiffness (moderate EPS)
- Elevated prolactin
Call us if you notice
- Tardive dyskinesia (involuntary movements)
- Neuroleptic malignant syndrome (NMS)
- Severe muscle stiffness or rigidity
- High fever with muscle changes
- Severe restlessness (akathisia)
- Unusual eye movements or neck spasms
Perphenazine has a more balanced side effect profile than high-potency agents — less EPS than haloperidol but more sedation. It is one of the most cost-effective antipsychotics available and was shown to perform well against newer medications in the CATIE study.
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Tips for Success
Same Time DailyTake at the same time each day for consistent levels in your system.
With FoodTaking with food reduces nausea and stomach upset.
Don't Stop AbruptlyAlways taper with your provider guidance — stopping suddenly can cause rebound symptoms.
Avoid AlcoholAlcohol increases sedation and side effects significantly.
Tell All ProvidersLet other prescribers know what you are taking — interactions matter.
Track SymptomsNote any unusual movements, mood changes, or new symptoms and share with your provider.
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Important Safety Information
Tardive Dyskinesia — BLACK BOX WARNING: Long-term use can cause permanent involuntary movements of the face, tongue, lips, or limbs. Risk increases with dose and duration. Report any unusual movements immediately — early detection is critical.
Neuroleptic Malignant Syndrome (NMS): A rare but life-threatening reaction causing high fever, severe muscle rigidity, confusion, and unstable vital signs. Seek emergency care immediately if these occur.
Elderly Patients with Dementia: First-generation antipsychotics carry a black box warning for increased risk of death in elderly patients with dementia-related psychosis. Not approved for this use.
QT Prolongation: Many first-generation antipsychotics can affect heart rhythm. Tell your provider about any heart conditions or other medications that affect the heart.
Pregnancy & Breastfeeding: Discuss risks and benefits with your provider. Do not stop without consultation.
Drug Interactions: First-generation antipsychotics interact with many medications including other CNS depressants and anticholinergics. Always share your full medication list.
Questions? I am here.
Reach me between appointments if you have concerns about side effects, notice mood changes, or have questions about your medication.
360-389-3712
info@rootedmindspsychiatry.com