Promethazine – Injection, Intravenous


Promethazine injection should never be used in children under 2 years of age and should be used with caution in children over 2. It has the potential to cause tissue damage, including gangrene regardless of how or where it is injected. Deep muscle injection is the preferred route to prevent tissue damage. Intravenous administration is the other approved route. Promethazine should never be injected just under the skin (subctuaneously).

What Is Promethazine: Injection and Intravenous?

Promethazine hydrochloride is a prescription injectable medication used to treat and prevent nausea and vomiting. It can also treat certain types of allergic reactions or be used in addition to other therapies as an add-on analgesic or anesthetic during surgery.

Promethazine works as an antihistamine and has sedative and antiemetic (antinausea) effects. It also has anticholinergic properties, meaning it blocks the activity of the neurotransmitter acetylcholine in the central and peripheral nervous systems. This neurotransmitter is involved in involuntary muscle movements and other functions of the body.

Promethazine is injected either deep into the muscle (intramuscular) or given intravenously (IV, within a vein). It is also available in rectal and oral formulations. This article will focus on the injectable and intravenous versions.

Drug Facts

Generic Name: Promethazine hydrochloride

Brand Name(s): Phenergan (discontinued)

Drug Availability: Prescription

Administration Route: Intramuscular or intravenous

Therapeutic Classification: Antihistamine

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Promethazine

Dosage Form(s): Solution

What Is Promethazine Used For?

The Food and Drug Administration (FDA) approved promethazine to treat and prevent nausea and vomiting primarily in adults. However, it can be used with caution and monitoring in children over the age of 2. 

Additionally, promethazine may be used for certain types of allergic reactions, such as:

  • Allergic reactions to blood or plasma
  • Anaphylaxis as an add-on treatment with epinephrine and other standard measures
  • Other uncomplicated allergic conditions when oral therapy cannot be used

It is also sometimes used as an add-on therapy for pain control or anesthesia during surgery.

How to Use Promethazine: Injection

Promethazine will be given to you through a deep muscle injection or a large vein injection by a healthcare provider. You will not be able to administer this medication to yourself. Your provider and care team will determine if this medication is right for you and will determine how often it needs to be given.  

It is important to tell your provider if you experience any pain or burning at the injection site, especially if it persists or worsens over time. In addition, limit sun exposure while under the effects of promethazine. This medication may make you drowsy, so do not drive or operate machinery while under its effects.


Since you will be administered promethazine at a healthcare provider's office, you won't need to worry about storing the medication in your home. Your healthcare team will ensure the medication is stored under the correct conditions.

Off-Label Uses

Healthcare providers may prescribe promethazine for off-label uses, meaning for reasons not specifically indicated by the FDA.

Promethazine injection can be used for the control of opiate-induced nausea and vomiting and to treat and prevent nausea and vomiting after surgery.

How Long Does Promethazine Take to Work?

Promethazine begins to work within five minutes of intravenous injection and within 20 minutes of injection into the muscle. The effects normally last between four to six hours but can sometimes last up to 12 hours.

What Are the Side Effects of Promethazine?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at or 800-FDA-1088.

Common Side Effects

The most common side effects of injectable or intravenous promethazine include:

  • Drowsiness
  • Mild irritation or pain at the injection site
  • Dizziness
  • Dry mouth
  • Sensitivity to sunlight
  • Fatigue

Severe Side Effects

Call your healthcare provider immediately if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects can include:

  • Severe pain at the injection site
  • Difficulty breathing
  • Increased or decreased blood pressure
  • Hallucinations
  • Changes in heart rate, such as tachycardia (fast heart rate) or bradycardia (slow heart rate)
  • Tissue injury at the injection site

Promethazine injection can cause potentially fatal respiratory depression if used in children younger than 2. Therefore, it should not be given to this age group.

Long-Term Side Effects

Most side effects of injectable promethazine resolve after the medication has worn off, but severe pain at the injection site that worsens or persists may lead to severe health issues, such as tissue damage and gangrene. If these conditions are not prevented or controlled quickly, serious invasive treatments such as surgery, skin graft (transplanting skin from another area) or amputation (surgical removal) may be required.

Report Side Effects

Promethazine may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Promethazine Should I Use?

This medication will be administered to you via deep muscle injection or through an IV by a trained healthcare provider. They will determine the appropriate dosage for you.


Promethazine is not to be used in children under 2 years of age. In children older than 2 years, this medication is not to be used in those with liver problems. 

Having kidney disease does not affect how much of this drug you will be given, and your dose will not need to be adjusted. 

Dosage adjustments may be required for:

  • Adults 60 and older: It is recommended to start at the lowest dose and slowly increase the dose until effective.
  • People taking narcotics: A healthcare provider may decrease the dose of the narcotics.
  • People taking barbiturates: The dose of those medications should be decreased.

Missed Dose

If you miss a dose of promethazine, inform your healthcare provider so they can decide if you need another dose.  As you will not be giving yourself doses, there is little risk of your missing a dose or accidentally receiving an extra dose.

Overdose: What Happens If I Use Too Much Promethazine?

Someone with a mild or moderate overdose on injectable or intravenous promethazine may display symptoms such as:

  • Extreme fatigue
  • Flushing
  • Fever
  • Dry mouth
  • Increased heart rate
  • Hallucinations

A person who has severely overdosed may show symptoms such as:

  • Psychosis
  • Seizures
  • Heart arrhythmia
  • Coma

Healthcare providers are trained in identifying and addressing overdoses, and they will respond appropriately.

What Happens If I Overdose on Promethazine?

If you think you or someone else may have overdosed on promethazine, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking promethazine, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check the progress of you or your child at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

This medicine contains sodium metabisulfite. Make sure your doctor knows if you or your child have had an allergic reaction to sulfite in the past.

Check with your doctor right away if you or your child have burning, persistent or worsening pain at the injection site; or any involuntary muscle movements after receiving this medicine.

This medicine may affect blood sugar levels. If you or your child notice a change in the results of your blood or urine sugar tests or if you have any questions, check with your doctor.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, antidepressants, or sleeping medicine; prescription pain medicine or narcotics; medicine for seizures or barbiturates; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your medical doctor or dentist before taking any of the above while you or your child are taking this medicine.

Check with your doctor right away if you or your child have pale or blue lips, fingernails, or skin; difficult or troubled breathing; irregular, fast, slow, or shallow breathing; or shortness of breath. These could be signs of a condition called respiratory depression.

This medicine may cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Even if taken at bedtime, it may cause some people to feel drowsy or less alert on arising. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert.

Promethazine can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. If you can, avoid people with infections. Check with your doctor immediately if you or your child think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.

Check with your doctor right away if you or your child are having convulsions, difficulty in breathing, fast heartbeat, high fever, high or low blood pressure, increased sweating, loss of bladder control, severe muscle stiffness, unusually pale skin, or tiredness. These could be symptoms of a serious condition called neuroleptic malignant syndrome (NMS).

Check with your doctor right away if you or your child have pain or tenderness in the upper stomach; pale stools; dark urine; loss of appetite; nausea; unusual tiredness or weakness; or yellow eyes or skin. These could be symptoms of a liver problem.

Before you have any medical tests, tell the medical doctor in charge that you or your child are receiving this medicine. The results of some tests may be affected by this medicine.

This medicine may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

This medicine may make your skin more sensitive to sunlight. Use a sunscreen when you are outdoors. Avoid sunlamps and tanning beds.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Use Promethazine?

If you have a history of seizures or liver disease, consult your healthcare provider before receiving promethazine. Promethazine can worsen these diseases. 

Older adults (aged 60 and older) may have a higher risk of experiencing side effects, so discussing the risks and benefits of treatment with your healthcare provider is important.

Before receiving promethazine, also tell your healthcare provider if you have:

  • Narrow-angle glaucoma (eye condition in which fluid cannot drain from the eye)
  • Prostatic hypertrophy (prostate gland enlargement)
  • Stenosing peptic ulcer (narrowing of the pyloric canal, the opening between the stomach and duodenum, due to swelling and scarring)
  • Pyloroduodenal obstruction (gastric outlet blockage)
  • Bladder-neck obstruction
  • Heart disease

What Other Medications Interact With Promethazine?

Before starting treatment, tell your healthcare provider about any other medicines you take or plan to take, including over-the-counter (OTC) nonprescription products, vitamins, herbs, supplements, and plant-based medicines.

Promethazine can enhance the sedative action of central nervous system depressants, such as:

  • Certain antipsychotic medications, such as Geodon (ziprasidone) and thioridazine
  • Barbiturates
  • General anesthetics
  • Narcotics

Before receiving promethazine, tell your healthcare provider if you're on any of these medications. They may avoid promethazine altogether or reduce the dose of your other medications.

These are the most severe and common drug interactions regarding promethazine, but many more exist. Always check with your healthcare provider or pharmacist when prescribed promethazine to ensure it does not interact with any other medications.

What Medications Are Similar?

Other medications used for similar purposes as promethazine are available.

These include:

  • Zofran (ondansetron): This medication treats nausea and vomiting and comes as a tablet or orally disintegrating tablet. It works in a completely different way in the body than promethazine.
  • Reglan (metoclopramide): This medication also prevents and treats nausea and vomiting, and it too works differently in the body than promethazine to produce its effects.
  • Claritin (loratadine): This OTC medication is used to treat allergic reactions and is often preferred over promethazine because it causes less drowsiness.

This list includes drugs also prescribed for nausea and vomiting, as well as allergic reactions. It is not a list of drugs recommended to take with promethazine. Talk to your pharmacist or a healthcare provider if you have questions.

Frequently Asked Questions

  • Can I use promethazine when pregnant or breastfeeding?

    There are no adequate and well-controlled studies on promethazine's use in pregnancy. Therefore, the risk to the fetus of using promethazine while pregnant cannot be ruled out. It is important to have a full conversation with your healthcare provider regarding your pregnancy before using promethazine. 

    Although it appears safe to use while breastfeeding with occasional, short-term use, repeated doses have caused oversedation in breastfed infants. It may also interfere with lactation (breastfeeding) if given during labor.

  • How do I stop using promethazine?

    This medication does not require any tapering down of dosing, nor is it associated with any withdrawal symptoms. When your healthcare provider no longer thinks you need promethazine, it can be stopped immediately with no problems.

  • Can I take promethazine in an oral form?

    Yes. If your healthcare provider feels it is appropriate, promethazine is available as an oral tablet, oral liquid, and rectal suppository. Injectable promethazine is often reserved for an inpatient setting. Your provider can help you determine which formulation is best for you.

How Can I Stay Healthy While Taking Promethazine?

After receiving promethazine, it is important that you tell your healthcare provider if you are experiencing any pain, irritation, or burning at or near the site of the injection. This can lead to severe and long-term negative effects if this is not addressed. 

If possible, give your healthcare team a current, up-to-date list of all medications, supplements, and herbal products that you are taking to prevent potential interactions. 

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

The author would like to recognize and thank Jonathan Toellner for contributing to this article.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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