Promethazine (Phenergan, Promacot, Phenadoz, Promethegan, Remsed, Antinaus50)
January 30, 20190782

What is Promethazine?

Promethazine (promethazine hydrochloride) is a widely prescribed drug that is used to treat allergy symptoms. These symptoms include runny nose, sneezing, itching, and watery eyes.

It is also used to treat nausea and pain, especially after surgery. It might be prescribed to prevent motion sickness, and as a mild sedative or sleep aid.

Promethazine is only available as a prescription drug. It is sold under a number of brand names: Phenergan, Promacot, Phenadoz, Promethegan, Remsed, and Antinaus50.

Promethazine Classification

Medically, promethazine is a member of the family of drugs called phenothizaines. These drugs are mildly psychoactive (changes brain function, mood, or perception) and they work by changing the actions of chemicals in your brain. Promethazine also works as an antihistamine, and so it limits the effects of the natural chemical histamine in your body.[1]

Promethazine comes in several forms: oral tablets (in 12.5mg, 25mg, and 50mg dosages), suppositories (in the same dosages), as an injectable solution (25mg/ML and 50mg/ML), and as a syrup (6.25mg/5mlL).

Promethazine syrup is often combined with dextromethorphan (as Promethazine DM or Phenergan DM) or with codeine (Promethazine Codeine) as a prescription cough syrup.

In all of these forms, promethazine is only prescribed to control symptoms, and it does not treat the actual cause of symptoms or speed your recovery.[2]

Important Warnings: Although promethazine is safe when used as prescribed, it does come with several strong warnings, especially with regard to children.[3] There are also some potential side effects and the drug can be abused, so if it has been prescribed for you, you should read the Promethazine Side Effects and Warnings for Promethazine sections that follow.

Promethazine Uses

Promethazine is usually prescribed as an antihistamine, which treats the symptoms of common allergic reactions. It might also be prescribed along with other drugs to treat more serious allergic reactions such as anaphylaxis. In addition, your doctor may give you promethazine to suppress symptoms of the common cold such as cough, sneezing, and runny nose.

In hospitals, promethazine can also be used to help you relax before surgery and during labor, and it can also be used to control nausea after an operation. It can also be prescribed to treat pain because phenothizaines increase the strength of some narcotic pain killers. For home use, promethazine is often used as a sleep aid or to prevent motion sickness while traveling.1

Promethazine Dosage (How to Use)

Because promethazine can be used to treat so many symptoms, the dosage and frequency you need may vary. You should always follow your personal doctor’s instructions. You should take note of the following general guidelines.

  • General guidelines
    • Never take more or less than the dosage prescribed by your doctor.
    • If using promethazine syrup, do not use a household spoon to measure your dose. Only use the measuring cup or spoon that comes with the medication.
    • WARNINGNever give promethazine to children younger than 2 years old. Give promethazine only with caution to children younger than 16 years old. Before doing so carefully read the Warnings for Promethazine section of this article. Follow your doctor’s advice as to dosage and frequency exactly.
  • Allergy symptoms – take as directed, one to four times per day. A common adult dosage is one 25mg tablet at bedtime and one 12.5mg tablet before meals.
  • Cold symptoms – take as needed, no more often than one tablet or dose every 4 to 6 hours.
  • Nausea and vomiting – take one dose every 4 to 6 hours as needed. For motion sickness, take one dose 30 to 60 minutes before traveling and again after 8 to 12 hours if you need it. On longer trips, your doctor may suggest taking it in the morning or before the evening meal on each travel day.
  • As a sleep aid – take one dose – and never more than the suggested dose – at bedtime.1

If you miss a dose at its normal time, take it as soon as you remember. But if it is almost time for your next regular dose, wait until the next time you are supposed to take it. Do not take more medicine to “make up” for a missed dose.1

There are no specific foods to avoid when taking promethazine. However, you should let your doctor know if you are taking other prescription or over-the-counter drugs, vitamins, or herbal products, because they can affect how promethazine works. 1

You should ask your doctor about the use of alcohol when taking promethazine, and follow his or her recommendations carefully. Because promethazine can interfere with your breathing, you especially shouldn’t combine it with alcohol before bedtime. Alcohol also makes certain side effects of promethazine more likely to occur, and can intensify them.1

Taking promethazine can make you drowsy. This is especially true of cough syrups that contain promethazine and dextromethorphan or codeine. Do not drive or use heavy machinery until you know how the drug affects you. 2

Store promethazine in the container it came in, safely out of the reach of children. Promethazine tablets and liquid should be kept at room temperature and away from direct sunlight, heat, and moisture. Store promethazine suppositories in the refrigerator. 2

Promethazine Side Effects

Promethazine can have a number of side effects. Antihistamines can make you drowsy and slow your reaction time, and it can also affect your mind, making you feel confused and disoriented.

Common Side Effects

Tell your doctor if any of these symptoms become severe or do not go away:

  • dry mouth
  • dizziness
  • blurred or double vision
  • drowsiness and a lack of energy
  • trouble falling asleep or staying asleep, nightmares
  • clumsiness
  • nausea or vomiting
  • ringing in ears
  • feeling nervous or like you have too much energy
  • an unusually happy or giddy mood
  • stuffy nose
  • itching1,2

More Serious Side Effects

Call your doctor right away if you have any of these symptoms:

  • signs of an allergic reaction such as hives, swelling, or trouble breathing
  • uncontrolled muscle movements in your facial area
  • slowed breathing, or breathing that stops for a short time
  • fever, chills, too much sweating
  • stiff (rigid) muscles
  • fast or uneven pulse or heartbeat
  • feeling less alert
  • fainting or a sudden light-headed feeling
  • abnormal or uncontrolled movements
  • hallucinations (seeing or hearing things that do not exist)
  • confusion or serious unrest
  • serious fears or overwhelming emotions
  • seizures
  • uncontrolled shaking of a part of the body
  • unusual bruising or bleeding
  • sore throat, fever, chills, and other signs of infection
  • uncontrolled eye movements
  • tongue sticking out
  • abnormal neck position
  • a feeling like you can’t to respond to people around you
  • yellow skin or eyes
  • swelling of the face, eyes, lips, tongue, throat, arms, hands, feet, or ankles
  • hoarseness, difficulty speaking
  • trouble breathing or swallowing1,2

Many other side effects are possible. To be safe, call your doctor if you have any unusual problems while taking promethazine.

Warnings for Promethazine


Promethazine can cause breathing to slow or stop, and can cause death in children. Promethazine should never be given to babies or children under the age of 2. Products such as cough syrups that combine promethazine with dextromethorphan (Promethazine DM) or with codeine (Promethazine Codeine) should not be given to children under 16.2

In 2004, a “boxed warning” was added to the labeling for promethazine. The label states that it is not for use in children less than 2 years of age, and gives strong parental warnings on its use in older children.3

Promethazine should be given with caution to children between the ages of 2 and 16. Let your doctor know if your child has any breathing condition such as asthma, lung disease, or sleep apnea. Also tell the doctor if the child takes any drugs that can impair breathing. These include anxiety medications, sedatives, some painkillers, and sleeping pills. Watch the child carefully after giving promethazine. Call your doctor or emergency services if your child has any trouble breathing, pauses in breathing, or wheezing.2

General Warnings

Don’t miss any follow-up appointments with your doctor. It is important that your physician check your progress regularly to make sure that promethazine is working well.

It can make you drowsy or dizzy, so do not drive a car or use dangerous machinery until you are sure how the drug affects you.1

Tell any doctor or dentist whom you see for other conditions that you are taking promethazine. It can affect medical test results, including the outcome of pregnancy tests.2

Promethazine can increase the effects of alcohol and other central nervous system (CNS) depressants. Examples of these include antihistamines or allergy medicines, tranquilizers and antidepressants, barbiturates, sleeping pills, some prescription pain medications, muscle relaxants, and seizure medications. Check with your doctor before taking any of these drugs while taking promethazine. 2

Taking promethazine may cause your skin to become more sensitive to the sun. So avoid sunlamps and tanning beds, and remember to use a sunscreen when you are outdoors.1

Warnings for Special Groups


As previously noted, the use of promethazine for children between the ages of 2 and 16 should be closely watched to make sure that it does not affect the child’s breathing. Doctors give promethazine to children based on the child’s age and weight. So, do not re-use old medications without checking with your doctor to make sure the dosage and frequency of use are still correct.1,2

Pregnant or Breastfeeding Women

Before taking promethazine, let your doctor know if you are pregnant or breastfeeding. There are no definitive studies showing any problems. However, as with all drugs, the decision on taking promethazine should be made between you and your doctor.1

Older People

Older people may be more sensitive to the side effects of promethazine such as confusion and severe drowsiness. If you are over 65 you should talk with your doctor about it. Older adults are more likely to have age-related conditions such as heart disease, liver or kidney problems, or cardiovascular disease. All of these conditions can require a change of dosage or choosing another medication.1

Other Medical Conditions

Certain other medical conditions can affect the use of this medicine. If you have been diagnosed with sleep apnea, promethazine may not be right for you. This may also be true if you have certain breathing or lung problems, an enlarged prostate, jaundice or liver disease, stomach ulcers, or a history of seizures. So be very open with your doctor about your present and past medical history before deciding to take promethazine.2

Previous History of Allergic Reactions

Let your doctor know if you have ever had any allergic reaction to promethazine or any other phenothiazine medicine. Also tell your physician about any other allergies you have, such as to animals, foods, dyes, or preservatives.

Drug Interactions

Some drugs can affect the way that promethazine works. The use of promethazine with any of the following drugs is not recommended:1

  • Amifampridine
  • Amisulpride
  • Bepridil
  • Bromopride
  • Cisapride
  • Dronedarone
  • Mesoridazine
  • Metoclopramide
  • Pimozide
  • Piperaquine
  • Saquinavir
  • Sodium Oxybate
  • Sparfloxacin
  • Terfenadine
  • Thioridazine
  • Ziprasidone

In addition, there is a long list of medications that can interact poorly with promethazine. Taking promethazine at the same time you take one of these drugs may not be the best idea, but may be needed in some cases.

So be very clear with your doctor about ALL medications, vitamins, and herbal products you take. Any of them could affect your doctor’s decision to prescribe promethazine, or which dosage to prescribe. Even common supplements like evening primrose, betel nut, and phenylalanine can increase the risk of promethazine side effects.1

Abuses of Promethazine

Promethazine, like all phenothiazine drugs, has some psychoactive properties. However, these effects are rarely strong enough that anyone would want to use the tablet or suppository forms to get a “promethazine high.”

The dangers of abuse come mainly from its interactions with other drugs. For example, promethazine heightens and intensifies the actions of opioid painkillers, so some people may attempt to take it to enhance the “high” they feel from those drugs.1,2

The main source of promethazine drug abuse is in the use of combination promethazine products, such as Promethazine Codeine cough syrup. The liquid form of promethazine is easy to consume and invites overuse or even non-prescription use. This is especially true for those who may already have a problem with opioid addiction.[4],[5] One 2013 study found traces of promethazine in the urine of 26% of participants in a methadone maintenance program to combat their injection drug use.[6]

That said, it is possible to take too much promethazine. If it is prescribed for you or a family member, you should read the following information about overdosing.


In case of overdose, you should call your local poison control center at 1-800-222-1212 immediately. If the person has collapsed or is not breathing, you should call emergency services at 911.

Symptoms of promethazine overdose may include:1,2

  • trouble breathing
  • slowed or stopped breathing
  • depression, loss of interest or pleasure
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position quickly
  • loss of consciousness
  • fast heartbeat
  • tight (rigid) muscles that are difficult to move
  • loss of coordination, shakiness and unsteady walk
  • feelings of warmth
  • lack of appetite
  • irritability
  • continuous twisting movements of the hands and feet
  • dry mouth
  • dilated pupils (black circles in the middle of the eyes)
  • flushing – redness of the face, neck, arms, or chest
  • nausea
  • constipation
  • abnormal excitement or unrest
  • nightmares or trouble sleeping

Promethazine Compared to Other Similar Drugs for Treating Nausea

Ondansetron (Zofran) vs. Promethazine (Phenergan)

Zofran (ondansetron) is used to prevent nausea and vomiting, especially that caused by chemotherapy, radiation therapy, and surgery. Its main advantage is that it comes in a freeze-dried oral form that dissolves on your tongue, so you don’t have to swallow the tablets with liquid.[7]

Phenergan (promethazine) also works well as an anti-nausea medication, is relatively cheap, and comes in many forms to make it easier to take. Its disadvantages are that it can make you sleepy, that it cannot be used by children under 2, and that in many cases it should not be used by adults over 65.1,2

In at least one 2008 clinical trial, promethazine and ordansetron were found to have similar success in reducing nausea among emergency department visitors. Reductions in patient anxiety were similar, but promethazine produced more sedation.[8]

Prochlorperazine (Compazine) vs. Promethazine (Phenergan)

Compazine (prochlorperazine) is an antipsychotic medication, but is also used to treat nausea and vomiting. It is a phenothiazine medication, like promethazine, and works by blocking receptors in the brain that trigger nausea. It is available in tablet and suppository form.

Compazine is effective, but like promethazine it should not be given to children under the age of 2. It is also a poor choice for some elderly people, especially those who have dementia, a brain disorder that affects memory, thinking, and communication. In such individuals, prochlorperazine can cause changes in mood and personality, and is associated with an increased chance of death.[9]

In at least one clinical trial in an emergency department setting, prochlorperazine reduced symptoms of nausea and vomiting more quickly than promethazine.[10]

Cyclizine vs. Promethazine

Cyclizine (cyclizine hydrochloride) is an antihistamine used to treat and prevent nausea, vomiting, and dizziness due to motion sickness or vertigo. It can also be used to treat the more serious vomiting associated with surgery or narcotic painkillers. It is sold in tablet and liquid forms, and is available in the United States without a prescription.

One disadvantage compared to promethazine is that cyclizine should not be used by children under the age of 6. It also may not be a good choice for people with glaucoma, hepatic disease, hypertension, severe heart failure, epilepsy, porphyria, and several other conditions. There have been few clinical studies, but some reports note that it may be slightly less effective for nausea than promethazine.[11]

Promethazine FAQs

I am allergic to Compazine. Can I take Promethazine?

Compazine (prochlorperazine) is classed as a phenothiazine medication like promethazine. Therefore there is a strong chance that if you are allergic to one you will be allergic to the other. Check with your doctor to be sure.9

Can promethazine be used for pain?

Promethazine is not an analgesic (painkiller) per se. However it can be used to help you go to sleep and thus control your pain or anxiety, especially before or after surgery. Promethazine is also known to intensify the effects of opioid painkillers, so it may be given to you to make them more effective.1.2

Is Promethazine with DM a narcotic?

Promethazine DM (promethazine with dextromethorphan) is not a narcotic. It is used as a cough suppressant because it acts like an antihistamine. Promethazine Codeine cough syrups are narcotic, however, because codeine is a narcotic.1

How long does it take for promethazine to work?

Promethazine taken orally is well absorbed from the stomach and intestines. The effect should occur within 20 minutes, and lasts for 4 to 6 hours.[12]

Does promethazine make you sleepy?

Promethazine is an antihistamine, so it definitely can make you drowsy. It is actually used in some cases as a sleep aid. People who take promethazine are advised to not drive a car or use dangerous machinery until they know how the drug affects them.1,2

Is promethazine a controlled substance?

Promethazine is non-narcotic, and is therefore not a controlled substance. It does, however, need a prescription.1,2

Is promethazine an antipsychotic?

Promethazine is an antihistamine of the phenothiazine family. It can make you very sleepy and might make you feel confused. In emergency departments, promethazine is sometimes used with haloperidol to calm people down who are very upset due to a loss of contact with reality.[13]


  1. PubMed Health. Promethazine. Accessed July 27, 2017.
  2. MedLine Plus, Promethazine. Accessed on July 26, 2017.
  3. New England Journal of Medicine. Boxed Warning Added to Promethazine Labeling for Pediatric Use. Accessed on July 27, 2017.
  4. National Institute on Drug Abuse. Cough and Cold Medicine Abuse. Accessed on July 28, 2017.
  5. Facts About Promethazine. Accessed on July 28, 2017.
  6. Shapiro BJ, Lynch KL, et al. Promethazine misuse among methadone maintenance patients and community-based injection drug users. Journal of Addiction Medicine. 2013 Mar-Apr;7(2):96-101. doi: 10.1097/ADM.0b013e31827f9b43
  7. MedLine Plus, Ondansetron.  Accessed on July 28, 2017.
  8. Braude D, Crandall C. Ondansetron versus promethazine to treat acute undifferentiated nausea in the emergency department; a randomized, double-blind, noninferiority trial. Academic Emergency Medicine. 2008 Mar;15(3):209-15. doi: 10.1111/j.1553-2712.2008.00060.x.
  9. MedLine Plus, Prochlorperazine. Accessed on July 28, 2017.
  10. Ernst AA, Weiss SJ, et al. Prochlorperazine versus promethazine for uncomplicated nausea and vomiting in the emergency department: a randomized, double-blind clinical trial. Annals of Emergency Medicine. 2000 Aug.36(2) e9-94.
  11. Electronic Medicines Compendium (eMC), Cyclizine 50mg Tablets. , 2017.
  12. PubMed Health Dailymed. Phenergan. Accessed on July 28, 2017.
  13. PubMed Health. Haloperidol plus promethazine for psychosis-induced aggression. Accessed on July 28, 2017.


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