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Serentil Side Effects

Generic name: mesoridazine

Note: This document contains side effect information about mesoridazine. Some dosage forms listed on this page may not apply to the brand name Serentil.

Applies to mesoridazine: injectable solution, oral concentrate, oral tablet.


In rare cases, mesoridazine has caused serious irregular heartbeats, sometimes resulting in death. Do not take mesoridazine if you have any of the following conditions or a history of these conditions: heart disease; an irregular heartbeat or a history of irregular heartbeats; a history of prolonged QT intervals; a family history of congenital long QT syndrome; hypokalemia (low levels of potassium in your blood); slow heartbeats that require treatment; or other heartbeat disturbances. These conditions may increase the risk of irregular heartbeats, heart attack, and death while taking mesoridazine.

Do not take mesoridazine with other drugs that can affect heartbeat rhythms such as quinidine (Cardioquin, Quinaglute, Quinidex, others), procainamide (Procan, Procanbid, Pronestyl), disopyramide (Norpace), and others. Taken with any of these drugs, mesoridazine (Serentil) may cause irregular heartbeats that could lead to death. This is not a complete list of drugs that may interact with mesoridazine and cause heart problems. Talk to your doctor or pharmacist before taking any other prescription or over-the-counter medications.

Call your doctor immediately if you have uncontrollable movements of the mouth, tongue, cheeks, jaw, arms, or legs; fever; muscle rigidity; sweating; irregular pulse; or fast or irregular heartbeats.

Use caution when driving, operating machinery, or performing other hazardous activities. Mesoridazine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

Dizziness may be more likely to occur when you rise from a sitting or lying position. Rise slowly to prevent dizziness and a possible fall.

Mesoridazine may interact with other drugs that cause drowsiness, including alcohol, antidepressants, antihistamines, pain relievers, anxiety medicines, seizure medicines, and muscle relaxants. Dangerous sedation, dizziness, or drowsiness may occur if mesoridazine is taken with alcohol or any of these medications. Talk to your doctor before taking mesoridazine in combination with alcohol or any other prescription or over-the-counter medicines.

Do not mix the liquid form of this medication with coffee, cola, or tea.

If you experience any of the following serious side effects, stop taking mesoridazine (the active ingredient contained in Serentil) and seek emergency medical treatment:

  • an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);

  • uncontrollable movements of the mouth, tongue, cheeks, jaw, arms, or legs;

  • fever;

  • muscle rigidity;

  • muscle spasms of the face or neck;

  • sweating;

  • irregular pulse;

  • fast or irregular heartbeats.

  • severe restlessness or tremor;

  • severe drowsiness;

  • blurred vision;

  • dizziness or fainting; or

  • a rash.

Other, less serious side effects may be more likely to occur. Continue to take mesoridazine and talk to your doctor if you experience:

  • dry mouth or stuffy nose;

  • constipation;

  • mild restlessness, drowsiness, or tremor;

  • difficult urination or dark urine;

  • decreased sex drive;

  • increased appetite; or

  • menstrual irregularities or swollen breasts.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

For Healthcare Professionals

Applies to mesoridazine: injectable solution, oral concentrate, oral tablet.


Drugs with the potential to prolong the QTc interval have been associated with torsades de pointes-type arrhythmias and sudden death.[Ref]

Cardiovascular side effects including hypotension and tachycardia have been reported. Mesoridazine has also been reported to prolong the QTc interval in a dose related manner.[Ref]

Nervous system

Central nervous system side effects including drowsiness, Parkinson's syndrome, dizziness, weakness, tremor, restlessness, ataxia, dystonia, rigidity, slurring, akathisia, and motoric reactions (opisthotonos) have been reported. Autonomic nervous system effects including dry mouth, nausea and vomiting, fainting, stuffy nose, photophobia, constipation, and blurred vision have also been reported.[Ref]

Adverse effects including rigidity and motoric effects tend to occur later in therapy.[Ref]


Genitourinary side effects including inhibition of ejaculation, impotence, enuresis, incontinence and priapism have been reported.[Ref]


Dermatologic side effects including itching, rash, hypertrophic papillae of the tongue, and angioneurotic edema have been reported.[Ref]


1. Product Information. Serentil (mesoridazine). Boehringer-Ingelheim. 2001.

2. Starck LC, Talley BJ, Brannan SK. Mesoridazine use and priapism [letter]. Am J Psychiatry. 1994;151:946.

3. Compton MT, Miller AH. Priapism associated with conventional and atypical antipsychotic medications: A review. J Clin Psychiatry. 2001;62:362-6.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.