First-Generation Antipsychotics for Treating Schizophrenia

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First-Generation Antipsychotics for Treating Schizophrenia


Generic Name

These medicines are available as tablets, a concentrated liquid, or an injection (shot). Long-acting formulas that are given every 2 to 4 weeks are available for fluphenazine and haloperidol.

How It Works

Experts don't know exactly how these antipsychotic medicines work. They think these medicines work because of how they affect brain chemicals (neurotransmitters). They usually are started at low doses to avoid side effects.

Why It Is Used

First-generation antipsychotics are used to reduce anxiety and agitation that often happen in schizophrenia. They can also reduce problems with thinking or remembering (cognitive impairment) and reduce or control delusions and hallucinations (psychosis).

How Well It Works

First-generation antipsychotics can reduce or control psychosis and improve thinking, mood, and behaviour. These medicines may help you return to a more normal daily life while living with schizophrenia.

First-generation antipsychotics may work differently in different people. For some people, these medicines may help with many symptoms, while other people may have to try other antipsychotic medicines to find the one that works best for them.

Side Effects

First-generation antipsychotic medicines can cause mild to severe problems with body movements.

  • Mild movement problems include restlessness, tremors, and rigid muscles. You may be able to reduce or stop these problems by taking a smaller dose of the medicine or by switching to another medicine. Your doctor also may be able to prescribe another medicine to block the movement problems.
  • A severe movement problem is tardive dyskinesia, which causes unusual body movements that you cannot control. Signs may include lip-smacking or continuous chewing, tongue-twitching or thrusting the tongue out of the mouth, or quick and jerky movements (tics) of the head.

Other serious side effects include:

  • Allergic reactions (skin rash, hives).
  • A lower white blood cell count. You will need blood tests to check this cell count while you are taking the medicine.
  • Neuroleptic malignant syndrome. This is a rare but life-threatening side effect of antipsychotics. The first signs usually include a fever between 38.9°C (102°F) and 39.4°C (102.9°F), a fast or irregular heartbeat, rapid breathing, and severe sweating.
  • Seizures.
  • Constant movement.
  • Muscle spasms, especially in the neck.
  • Abnormal heartbeat (arrhythmia).
  • Liver problems.
  • Low blood sugar (hypoglycemia).
  • Frequent urination.
  • Worsening of psychotic symptoms, such as hallucinations.

Other common, mild side effects include:

  • Drowsiness.
  • Low blood pressure.
  • Blurred vision.
  • Constipation.
  • Loss of appetite, feeling sick to your stomach, or vomiting.
  • Shaking, stiff muscles, and slow movement (typically seen in Parkinson's disease).

First-generation antipsychotics may raise levels of the hormone prolactin. This can lead to breast enlargement in both men and women and abnormal menstrual cycles in women.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

If you have any significant side effects while taking an antipsychotic, call your doctor right away. You may need another type of medicine, or the dose may need to be lowered.

There is some evidence of a link between first-generation antipsychotics (such as haloperidol) and an increase in cardiac arrest (heart stopping) or abnormal heartbeat.1 But it is not yet clear whether the risk is linked with the medicines or with schizophrenia.

If you have trouble taking antipsychotic medicines every day, you may be able to get a shot every 2 to 4 weeks. Talk with your doctor about whether this would be better for you.

You most likely will start by taking only a little of the medicine and then slowly take more. It may take several weeks before you know the medicine is working and know the best dose. If you do not see any benefits within 6 weeks, ask your doctor if you need to try another type of medicine.

Do not abruptly stop taking these medicines. Do not skip doses. If you forget to take a dose, take it as soon as you remember, but do not take more than one dose at a time.

The first-generation and second-generation antipsychotic medicines both can help the symptoms of schizophrenia. Which medicine is best for you usually depends on how well a medicine has worked for you in the past and its side effects. Your doctor will help you find the best medicine for you.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Durham J (2009). Schizophrenia: A review of pharmacologic and nonpharmacologic treatments. US Pharmacist, 34(11): 1–5.


By Healthwise Staff
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Primary Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer Miklos Ferenc Losonczy, MD, PhD - Psychiatry
Last Revised January 14, 2011

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.