First-generation antipsychotics for treating schizophrenia

Examples

These medicines can be taken orally as tablets or in a concentrated liquid, or they can also be injected.

How It Works

First-generation antipsychotics interfere with the transmission of brain chemicals, such as dopamine. They are usually started at low doses to avoid bothersome side effects associated with these medicines.

Why It Is Used

First-generation antipsychotics are used to reduce anxiety and agitation that often occur in schizophrenia. They can also improve coherence, reduce cognitive impairment, and stop delusions and hallucinations.

How Well It Works

First-generation antipsychotics can significantly reduce or control psychosis; improve thinking, mood, and behavior; and control some other conditions, such as Tourette's disorder.¹ These medicines may allow you to return to a more normal daily life while living with schizophrenia.

Side Effects

First-generation antipsychotic medicines can cause problems with your movements that are mild to severe.

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 may also be able to prescribe another medicine to block the movement problems.

A more severe movement problem is tardive dyskinesia, which causes unusual, uncontrollable body movements. These movements may include facial grimacing or eye-rolling.

It is important to have your blood monitored regularly when taking these medicines.

Other serious side effects include:

• Allergic reactions (skin rash, hives).
• Decreased white blood cell count (found by monitoring your blood levels while you are taking the medicine).
• Neuroleptic malignant syndrome, which includes a high fever and irregular heartbeat.
• 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, nausea, or vomiting.
• Shaking, stiff muscles, and slow movement (typically seen in Parkinson's disease).

First-generation antipsychotics may increase 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 experience any significant side effects while taking an antipsychotic, call your doctor immediately. 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 or thioridazine) and an increase in cardiac arrest (heart stopping) or abnormal heartbeat.² But it is not yet clear whether the risk is associated with the medicines or with schizophrenia.

If you have trouble taking daily doses of antipsychotic medicines, you may be able to have an injection every 2 to 4 weeks to control symptoms of schizophrenia. Talk with your doctor about whether an injection would work better for you.

Doses are usually started out low and then slowly increased over time as needed and as you can tolerate them. It may take several weeks before this medicine becomes effective or before you know if it is working for you. If you do not see any benefits within 6 weeks, another type of medicine may be tried to control your symptoms.

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.

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

References

Citations

1. Nadeem Z, et al. (2003). Schizophrenia. Clinical Evidence (9): 1103-1133.

2. Hennessy S, et al. (2002). Cardiac arrest and ventricular arrhythmia in patients taking antipsychotic drugs: Cohort study using administrative data. BMJ, 325(7372): 1070.

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