PROMETHAZINE (Phenergan): What is used for?

What is Promethazine?

Promethazine is a drug used in the treatment of urticaria, conjunctivitis, allergic manifestations and nausea. The product ingredient is Promethazine hydrochloride (hcl).

The brand names of promethazine are: Phenergan, Promethegan, Phenadoz, Adgan.

Mechanism of action of Promethazine

H1 receptor antagonist, anti-allergic.

Therapeutic indications, uses and benefits of Promethazine

Symptomatic treatment of allergic manifestations: seasonal or perennial rhinitis.

Allergic conjunctivitis, angioedema, mild urticaria.

Nausea, severe and prolonged vomiting of known etiology.

Prevention and treatment of kinetic dizziness.

Promethazine Dosage

Adults: 50-150 mg/day;
Children: 2-3 years: 2-15 mg; 3-8 years: 15-25 mg; 8-15 years: 25-50 mg; divided into several intakes.

Deep intramuscular injection in case of emergency.

Contraindications of Prometazine

  • Hypersensitivity to phenothiazines. Children < 2 years old.
  • Children with severe dehydration or acute illness (chickenpox, measles, CNS infection, gastroenteritis) due to risk of dystonia. Jaundice.
  • Bone marrow depression.
  • History of agranulocytosis with other phenothiazines.
  • Risk of urinary retention due to uroprostatic problems and closed-angle glaucoma.

Warnings and precautions with Prometazine

Severe liver failure/renal failure.

A history of seizures or brain damage and a family history of sudden infant death.

Epilepsy, monitoring.

Elderly people with tendency to orthostatic hypotension and vertigo with sedation, chronic constipation (risk of paralytic ileus), eventual prostatic hypertrophy.

Cardiovascular disease.

Avoid: prolonged exposure to sunlight; risky activity in children (bicycles, swings, etc.); in children and adolescents with signs suggestive of s. Reye.

Do not delay the administration of adrenaline if necessary.

Do not use with severe vomiting without establishing a causal agent for risk of masking symptoms of appendicitis, intestinal obstruction, s. Reye.

Extreme care in intramuscular injection administration to avoid extravasation or inadvertent subcutaneous injection; never via intraarterial (risk of severe arteriospasm and gangrene), nor SC (risk of local necrosis).

Liver failure


Kidney failure


Interactions with Promethazine

  • Sedation enhanced by: alcohol, do not associate.
  • Increased risk of “torsades de pointes” with: sultoprida, do not associate.
  • Central depression increased by: CNS depressants (sedatives, barbiturates, benzodiazepines, clonidine and similar, hypnotics, morphine derivatives, methadone, neuroleptics, anxiolytics).
  • Increased atropine effects with: atropine and atropine substances (imipramine antidepressants, antiparkinsonian anticholinergics, atropine antispasmodics, disopyramide, phenothiazine neuroleptics).
  • Reduced absorption by: antidiarrheal, antacids.
  • Intramuscular: do not mix with other drugs.

Pregnancy and Promethazine

To avoid by precaution in first quarter and not to prescribe except necessity and in any case for punctual use in third quarter.

If used at the end of pregnancy, monitor the neurological and digestive function of the newborn.


Promethazine passes into breast milk. Its administration should be avoided taking into account the possibilities of sedation or paradoxical arousal of the newborn and the associated risks of sleep apnea.

Effects on driving ability

Promethazine may cause drowsiness, especially at the beginning of treatment, which may affect the ability to drive and/or operate machines.

Patients should avoid operating dangerous machinery, including automobiles, until they know how to tolerate the medication.

Adverse reactions and side effects of Promethazine

Sedation, drowsiness.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID: 4927
NCI Thesaurus: C779

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