Skip to Content

Meprozine Side Effects

Generic Name: meperidine / promethazine

Note: This document contains side effect information about meperidine / promethazine. Some of the dosage forms listed on this page may not apply to the brand name Meprozine.

For the Consumer

Applies to meperidine / promethazine: oral capsule

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Very bad dizziness or passing out.
  • Fast or slow heartbeat.
  • A heartbeat that does not feel normal.
  • Fever or chills.
  • Sore throat.
  • Hallucinations (seeing or hearing things that are not there).
  • Mood changes.
  • Feeling confused.
  • Very hard stools (constipation).
  • Feeling very sleepy.
  • Chest pain.
  • Seizures.
  • Trouble breathing, slow breathing, or shallow breathing.
  • Shakiness.
  • Any unexplained bruising or bleeding.
  • Change in eyesight.
  • Yellow skin or eyes.
  • A very bad and sometimes deadly health problem called neuroleptic malignant syndrome (NMS) may happen. Call your doctor right away if you have any fever, muscle cramps or stiffness, dizziness, very bad headache, confusion, change in thinking, fast heartbeat, heartbeat that does not feel normal, or are sweating a lot.
  • Some people who take this drug may have muscle movements that cannot be controlled. Call your doctor right away if you have any trouble controlling body movements or if you have muscle problems with your tongue, face, mouth, or jaw like tongue sticking out, puffing cheeks, mouth puckering, or chewing.
  • A very bad and sometimes deadly health problem called serotonin syndrome may happen if you take this drug with drugs for depression, migraines, or certain other drugs. Call your doctor right away if you have agitation; change in balance; confusion; hallucinations; fever; fast or abnormal heartbeat; flushing; muscle twitching or stiffness; seizures; shivering or shaking; sweating a lot; very bad diarrhea, upset stomach, or throwing up; or very bad headache.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Upset stomach or throwing up.
  • Hard stools (constipation).
  • Dizziness.
  • Feeling sleepy.
  • Dry mouth.
  • Sweating a lot.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at

For Healthcare Professionals

Applies to meperidine/promethazine: injectable solution, oral capsule


The most frequently observed meperidine adverse reactions have included light-headedness, dizziness, sedation, nausea, vomiting, and sweating. Somnolence is the most prominent CNS effect reported with promethazine.[Ref]

Nervous system

Hyperexcitability and extrapyramidal movements have been reported following a single dose of promethazine.[Ref]


Common (1% to 10%): Lightheadedness, dizziness, sedation

Rare (less than 0.1%): Extrapyramidal reactions

Frequency not reported: Weakness, headache, tremor, uncoordinated muscle movements


Common (1% to 10%): Drowsiness

Frequency not reported: Sedation, somnolence, dizziness, confusion, extrapyramidal symptoms, lassitude, tremors, convulsive seizures, neuroleptic malignant syndrome[Ref]



Frequency not reported: Euphoria, dysphoria, agitation, transient hallucinations and disorientation


Frequency not reported: Confusion, disorientation, euphoria, nervousness, insomnia, excitation, catatonic-like states, hysteria, hallucinations, nightmares, agitation, paradoxical reactions, hyperexcitability[Ref]

Hyperexcitability and abnormal movements have been reported following a single dose of promethazine.[Ref]



Frequency not reported: Respiratory depression, respiratory arrest


Frequency not reported: Asthma, respiratory depression, apnea, nasal stuffiness[Ref]



Common (1% to 10%): Nausea, vomiting

Frequency not reported: Dry mouth, constipation, biliary-tract spasm


Frequency not reported: Dry mouth, nausea, vomiting, jaundice[Ref]



Frequency not reported: Phlebitis, hypotension, tachycardia, bradycardia, palpitation, syncope, circulatory depression, shock, cardiac arrest, faintness


Frequency not reported: Tachycardia, bradycardia, increased or decreased blood pressure, faintness[Ref]



Common (1% to 10%): Sweating

Frequency not reported: Facial flushing


Frequency not reported: Dermatitis, photosensitivity, urticaria angioneurotic edema[Ref]



Frequency not reported: Tinnitus, vertigo[Ref]



Frequency not reported: Leukopenia, thrombocytopenia, thrombocytopenic purpura, agranulocytosis[Ref]



Frequency not reported: Visual disturbances


Frequency not reported: Blurred vision, diplopia


1. Geller RJ "Meperidine in patient-controlled analgesia: a near-fatal mishap." Anesth Analg 76 (1993): 655-7

2. Stone PA, Macintyre PE, Jarvis DA "Norpethidine toxicity and patient controlled analgesia." Br J Anaesth 71 (1993): 738-40

3. Inturrisi CE "Disposition of narcotics in patients with renal disease." Am J Med 62 (1977): 528-9

4. Drotts DL, Vinson DR "Prochlorperazine induces akathisia in emergency patients." Ann Emerg Med 34 (1999): 469-75

5. Jones J, Sklar D, Dougherty J, White W "Randomized double-blind trial of intravenous prochlorperazine for the treatment of acute headache." JAMA 261 (1989): 1174-6

6. Marcantonio ER, Juarez G, Goldman L, et al. "The relationship of postoperative delirium with psychoactive medications." JAMA 272 (1994): 1518-22

7. Hagmeyer KO, Mauro LS, Mauro VF "Meperidine-related seizures associated with patient-controlled analgesia pumps." Ann Pharmacother 27 (1993): 29-32

8. "Product Information. Compazine (prochlorperazine)." SmithKline Beecham, Philadelphia, PA.

9. Shaw HL "Treatment of intractable cancer pain by electronically controlled parenteral infusion of analgesic drugs." Cancer 72 (1993): 3416-25

10. Samuels SI, Rabinov W "Difficulty reversing drug-induced coma in a patient with sleep apnea." Anesth Analg 65 (1986): 1222-4

11. Olver IN, Laidlaw CR, Matthews JP, Bishop JF, Hayes AM, Wolf M, Toner GC "A randomised double blind crossover study of domperidone and prochlorperazine suppositories for controlling emesis in outpatients receiving chemotherapy." Eur J Cancer 30a (1994): 426-9

12. Baker FM, Cook P "Compazine complications: a review." J Natl Med Assoc 73 (1981): 409-12

13. Olive JM, Masana L, Gonzalez J "Meperidine and reversible parkinsonism." Mov Disord 9 (1994): 115-6

14. Armstrong PJ, Bersten A "Normeperidine toxicity." Anesth Analg 65 (1986): 536-8

15. Boston Collaborative Drug Surveillance Program "Drug-induced extrapyramidal symptoms." JAMA 224 (1973): 889-91

16. Fogarty T, Murray GB "Psychiatric presentation of meperidine toxicity." J Clin Psychopharmacol 7 (1987): 116-7

17. Stanski DR, Cherry C, Bradley R, et al "Efficacy and safety of single doses of intramuscular ketorolac tromethamine compared with meperidine for postoperative pain." Pharmacotherapy 10 (1990): s40-4

18. Reutens DC, Stewart-Wynne EG "Norpethidine induced myoclonus in a patient with renal failure." J Neurol Neurosurg Psychiatry 52 (1989): 1450-1

19. Elloway R, Sherman S, Maas L, et al "Meperidine-induced bronchospasm." Gastrointest Endosc 38 (1992): 93

20. Hey VM, Ostick DG, Mazumder JK, Lord WD "Pethidine, metoclopramide and the gastro-oesophageal sphincter." Anaesthesia 36 (1981): 173-6

21. "Product Information. Demerol (meperidine)." Sanofi Winthrop Pharmaceuticals, New York, NY.

22. Reilly GD, Wood ML "Prochlorperazine--an unusual cause of lip ulceration." Acta Derm Venereol 64 (1984): 270-1

23. Duxbury AJ, Ead RD, Turner EP "Erosive cheilitis related to prochlorperazine maleate." Br Dent J 153 (1982): 271-2

24. Manser TJ, Warner JF "Neuroleptic malignant syndrome associated with prochlorperazine." South Med J 83 (1990): 73-4

25. "Product Information. Phenergan (promethazine)." Wyeth-Ayerst Laboratories, Philadelphia, PA.

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.

More about Meprozine (meperidine / promethazine)

Professional resources

Related treatment guides