Haloperidol is a traditional or conventional antipsychotic used to treat schizophrenia, mania and other forms of psychosis. It is a derivative of butyrophenone and it acts by blocking the effects of dopamine, a chemical in the brain that affects thinking, behavior and feelings.

However, there are several conditions for which the use of haloperidol is contraindicated. Some of these contraindications are absolute and the agent should not be used to treat patients with these conditions under any circumstances. Other contraindications are relative, meaning the drug may be used if the benefits outweigh the risks.

Absolute contraindications

• Previous history of acute stroke or coma
• Severe intoxication with alcohol or any other drug that acts as a central nervous system depressant
• Allergy to haloperidol or other drugs of the butyrophene class
• Heart disease

Relative contraindications

Special caution is advised in the presence of the following conditions:

• Parkinson’s disease or dementia with Lewy bodies
• Patients at risk of QT prolongation, a rare heart condition that increases the risk of arrhythmia originating in the ventricles
• Impaired liver function (the metabolism of haloperidol is mainly hepatic)
• In epileptic patients, haloperidol can reduce the threshold at which a convulsion may occur

• The effects of haloperidol are stronger in patients with hyperthyroidism and there is an increased risk of side effects in this patient group
• The intravenous administration of haloperidol injection can lead to postural hypotension and collapse