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Promethazine (Promethegan): Uses, Side Effects and Dosage

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Facts
Status:
Prescription (Rx) Boxed warning
Strength:
12.5 mg, 25 mg, 50 mg
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Active ingredient:
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Source: FDA drug labeling via NLM DailyMed · About this document

Patient information: uses, side effects, how to take - Promethazine

What Is Promethazine?

Promethazine is an antihistamine which can be taken by mouth as a tablet or syrup, rectally as a suppository, or by injection. It can be used for:

  • "hay fever," or, a stuffy runny nose from allergy
  • watery, itchy eyes due to inhaled allergies and foods
  • mild allergic skin reactions with itching and swelling
  • allergic reactions to blood or plasma
  • dermographism, a form of hives known as "skin writing"
  • serious allergic reactions along with epinephrine and other treatments
  • sedation before or after surgery, or during childbirth
  • prevention and control of nausea and vomiting after surgery
  • along with meperidine (demerol) or other pain medicines
  • sedation, relief of anxiety, and production of light sleep
  • from which the patient can be easily aroused
  • treatment and prevention of motion sickness

Who Should Not Use Promethazine?

Promethazine should not be given to:

  • children under two years of age
  • patients who are unconscious
  • patients who are allergic to promethazine, any of the ingredients in promethazine, or to other phenothiazines
  • patients with lung symptoms including asthma
  • children who are vomiting unless the vomiting is prolonged and there is a known cause

What Are The Risks?

The following are the major potential risks and side effects of promethazine therapy. However, this list is not complete.

  • Severe drowsiness and reduced mental alertness. Promethazine may cause drowsiness which may impair your ability to ride a bike, drive a car, or operate machinery. This may be worsened if taken with alcohol or other drugs that also cause central nervous system (CNS) slowing such as sedatives, pain medicines, tranquilizers or certain drugs for depression.

  • Serious breathing problems. Promethazine should not be used in patients with poor lung function such as chronic obstructive lung disease or breathing problems while sleeping (sleep apnea).
  • Increased risk of seizures. Promethazine should be used with caution in patients with seizures or who are on other medicines which may also increase the risk of seizures.
  • Bone-marrow problems and blood cell production. Promethazine should not be used in patients with bone-marrow problems or used with other drugs that affect the bone marrow’s production of blood cells.
  • Neuroleptic malignant syndrome. This potentially deadly syndrome includes symptoms such as fever, muscle rigidity, mental changes, changes in pulse or blood pressure, fast heartbeat, increased sweating or irregular heart rhythm.
  • The most common side effects are drowsiness, changes in blood pressure, skin reactions, blood cell changes and breathing problems. Increased excitability or abnormal movements may occur after one dose of promethazine. If they do, consult your doctor about using another medicine.

What Should I Tell My Healthcare Professional?

Before you start taking promethazine, tell your healthcare professional if you:

  • have narrow-angle glaucoma
  • have an enlarged prostate
  • have a stomach ulcer
  • have an intestinal blockage
  • have a bladder blockage
  • have heart problems
  • have liver problems
  • have breathing or lung problems
  • have sleep apnea (breathing problems when sleeping)
  • have seizures
  • drink alcohol
  • are trying to become pregnant, are already pregnant, or are breast-feeding

Can Other Medicines Or Food Affect Promethazine?

Promethazine and certain other medicines can interact with each other. Tell your healthcare professional about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Some medicines may affect how promethazine works or promethazine may affect how your other medicines work. Know the medicines you take. Keep a list of them with you to show your healthcare professional.

Especially tell your healthcare professional if you take:

  • medicines that affect your brain such as anti-anxiety medicine, sleeping pills, pain medicines, sedatives, narcotics, antidepressants or tranquilizers
  • epinephrine
  • a monoamine oxidase inhibitor (MAOI) which is used to treat depression or other mental disorders
  • medicines called anticholinergics

About this document

Source: FDA drug labeling via NLM DailyMed · Application number: ANDA 040596 · View the label on DailyMed

Revision date stated in the text: November 2022

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The information on this site does not replace the advice of a doctor or pharmacist.

Drug information for Promethazine

Rx or OTC
Prescription (Rx)?
  • This drug is available only with a prescription from a licensed healthcare provider.
  • Rx
Boxed warning Yes – this drug has a boxed warning (also called a black box warning), the strongest warning of the FDA.
Drug class Phenothiazine
Active ingredient Promethazine hydrochloride
Dosage form Tablet
Route Oral
Marketing status listed in the FDA NDC Directory
Company (applicant) ZYDUS PHARMS USA
FDA approval ANDA 040596Abbreviated New Drug Application (ANDA) – generic drug Approved November 18, 2005
Therapeutic equivalence (TE) code ABCodes starting with A mean the FDA rates the drug therapeutically equivalent to its reference drug (Orange Book).
Manufacturers 16 labelers list this drug on DailyMed
Packages (NDC)
Package
12.5 mg – 100 in 1 bottle NDC 68001-161-00
25 mg – 100 in 1 bottle NDC 68001-162-00
25 mg – 1000 in 1 bottle NDC 68001-162-08
25 mg – 500 in 1 bottle NDC 68001-162-03
50 mg – 100 in 1 bottle NDC 68001-163-00

Source: FDA drug labeling via NLM DailyMed, data as of October 31, 2026. FDA data (DailyMed, Orange Book, Drug Shortages, enforcement reports). Not a substitute for the advice of a doctor or pharmacist.