Overview: Promethazine is a medicine used to help with allergy symptoms, reduce or prevent nausea and vomiting in certain situations, or provide sedative or pain-relieving effects after surgery. It works by blocking certain histamine receptors in your body, which helps to reduce itching, sneezing, and other allergy symptoms. It also affects parts of the brain that control nausea and vomiting. Common side effects may include drowsiness, dizziness, confusion, and dry mouth. Promethazine is available as tablets and liquid that you take by mouth and as a rectal suppository. It can also be given as an injection by a healthcare provider.

Uses

What is promethazine used for?

Promethazine is commonly used for the following conditions.

Promethazine may also be used for other conditions as determined by your healthcare provider.

How does promethazine work (mechanism of action)?

Promethazine works by blocking certain histamine receptors in your body, which helps to reduce itching, sneezing, swelling, and other allergy symptoms. It also affects parts of the brain that control nausea and vomiting.

How is promethazine supplied (dosage forms)?

Brands and other names

  • Phenergan
  • Promethegan

Dosage forms and strengths

  • 6.25 mg/5 mL oral solution
  • 12.5 mg oral tablets
  • 25 mg oral tablets
  • 50 mg oral tablets
  • 12.5 mg rectal suppository 
  • 25 mg rectal suppository 
  • 50 mg rectal suppository

Promethazine is also available in injectable forms.

How should I store promethazine?

Oral Tablet. Promethazine oral tablets should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Oral Liquid. Promethazine oral liquid should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Protect from light.

Rectal Suppository. Promethazine rectal suppositories should be stored in a refrigerator, between 36 F to 46 F (2 C to 8 C).

Injection Liquid. Promethazine injection is usually given by a healthcare provider in a hospital or clinic. You will not store it at home.

Side Effects

What are the most common side effects of promethazine?

The most common side effects of promethazine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Drowsiness or lack of energy
  • Confusion or inability to think clearly
  • Dizziness or coordination problems 
  • Blurred vision
  • Nervousness or trouble sleeping
  • Tremor
  • Dry mouth
  • Nausea or vomiting
  • Hallucinations or feelings of intense happiness, pleasure, and well being
  • Changes in blood pressure or heart rate

There may be other side effects of promethazine that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of promethazine?

While less common, the most serious side effects of promethazine are described below, along with what to do if they happen.

Severe Allergic Reactions. Promethazine may cause allergic reactions, which can be serious. Stop using promethazine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Breathing Problems. Promethazine may cause slow or shallow breathing, especially if you have breathing problems from another condition or take other medicines that can slow your breathing. Tell your healthcare provider if you develop severe sleepiness or trouble breathing, especially when you start promethazine. Stop using promethazine and get emergency help if you have any of the following symptoms.

  • Changes in the color of your skin, including bluish color to your lips and fingernails
  • Confusion
  • Shortness of breath
  • Feeling dizzy, lightheaded, or fainting
  • Changes in your heart rate or rhythm, such as a fast, slow, pounding or skipping heartbeat
  • Slow or shallow breathing
  • Excessive sleepiness or trouble staying awake

Seizures. Promethazine may cause seizures, especially if you have a seizure disorder. There are many different types of seizures and some of them are not easy to recognize. Stop using promethazine and call your healthcare provider if you have any of the following signs that a seizure is happening or could happen.

  • Muscle twitching, jerking, spasms, tremors, or other uncontrolled movements
  • Stiffening of your arms and legs
  • Feeling anxious, nervous, confused, or a sense of dread
  • Feeling dizzy or lightheaded
  • Falling or losing consciousness

Bone Marrow Suppression. Promethazine may cause your bone marrow to not make enough cells. This can lead to low blood levels of important cells, such as red blood cells, white blood cells, platelets, and neutrophils. Bone marrow suppression can lead to infections or bleeding. This can be serious or even life-threatening. Keep all appointments to have your blood checked. Tell your healthcare provider right away if you have any of the following symptoms of bone marrow suppression.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infection
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Headache
  • Fast or abnormal heartbeat

Neuroleptic Malignant Syndrome (NMS). Promethazine can cause a rare but serious condition called neuroleptic malignant syndrome. NMS is a serious condition that can lead to death. Stop using  promethazine and call your healthcare provider right away if you have any of the following symptoms.

  • High fever
  • Muscle stiffness or rigidity, where it is hard to move
  • Changes in your breathing or heart rate
  • Increased sweating
  • Confusion

Jaundice. Promethazine may cause jaundice, where your skin or the whites of your eyes turn yellowish in color. Call your healthcare provider right away if you develop any of the following symptoms.

  • Yellowish eyes or skin
  • Stool (poop) that is clay-colored
  • Dark urine
  • Itchiness

Movement Problems. Promethazine may rarely cause involuntary movement problems, including shakiness, stiffness, or jerkiness. Call your healthcare provider right away if you develop any unusual or uncontrolled movements. 

Severe Tissue Injury. Promethazine injection can cause severe irritation and damage to tissues, which can lead to gangrene, tissue death, and other problems. You may need surgery to treat it. Tell your healthcare provider right away if you have persistent or worsening pain, or burning, at the injection site.

Warnings & Precautions

Who should not use promethazine?

Allergies to Ingredients. People who are allergic to any of the following should not use promethazine.

  • Promethazine 
  • Phenergan
  • Promethegan
  • Any other medicine known as a phenothiazine
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific promethazine products they stock.

Children. Promethazine should not be used in any child younger than two years of age. Slow or shallow breathing that can lead to death may occur. 

Lung Problems. Promethazine should not be used if you have asthma or other lung problems. Promethazine can make these conditions worse.

Decreased Awareness. Promethazine should not be used by people who are in a coma or who have decreased consciousness. Promethazine can make these conditions worse.

What should I know about promethazine before using it?

Do not use promethazine unless it has been prescribed to you by a healthcare provider. Use it as prescribed.

Do not share promethazine with other people, even if they have the same condition as you. It may harm them.

Keep promethazine out of the reach of children.

Use an accurate measuring device to measure your dose of liquid promethazine. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist to recommend an appropriate measuring device.

Some promethazine injectable products may contain an ingredient called sodium metabisulfite, a type of sulfite. If you have asthma, you may be more likely to have a sulfite allergy.

Promethazine suppositories are for rectal use only. Remove the suppository from the foil wrapper before inserting into the rectum.

Promethazine can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how promethazine affects you.

Promethazine can make your skin more sensitive to light from the sun, sunlamps, and tanning beds. This is called photosensitivity. Exposure to this light can cause severe sunburns, blisters, and swelling. If you need to be in sunlight, wear sunscreen, a hat, and clothing that covers your skin.

People who are 65 and older can be at greater risk for some side effects from promethazine. Talk to your healthcare provider about your risks if you are in this age group.

Promethazine may cause some laboratory tests to give false readings, including pregnancy tests and blood sugar tests. Talk to your healthcare provider if you have any concerns.  

What should I tell my healthcare provider before using promethazine?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if promethazine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following. 

  • Glaucoma 
  • Bladder or prostate problems 
  • Stomach or bowel problems
  • Heart problems 
  • Liver problems
  • Breathing problems, such as asthma, chronic obstructive pulmonary disease (COPD), or sleep apnea
  • Seizures
  • Bone marrow disorder

Other Medicines and Supplements. Promethazine may interact with other medicines and supplements. Before using promethazine, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how promethazine could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should use promethazine while you are pregnant or trying to get pregnant.

Breastfeeding. It is not known if promethazine passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should use promethazine while breastfeeding.

Interactions

Does promethazine interact with foods or drinks?

There are no known interactions between promethazine and foods or non-alcoholic drinks.

It is unknown if drinking alcohol will affect promethazine. The risk of drowsiness and dizziness may be increased if you drink alcohol while using promethazine.

Does promethazine interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using promethazine.

  • A barbiturate, such as phenobarbital, butalbital, or primidone, which is a medicine that may be used to treat insomnia, migraines, or seizures
  • An opioid, such as oxycodone, morphine, codeine, or fentanyl, which is a medicine used for certain types of pain
  • A tricyclic antidepressant, such as amitriptyline, nortriptyline, or protriptyline, even if it is not used for depression
  • Epinephrine, which is a medicine that is commonly used to treat severe allergic reactions or low blood pressure in emergency situations
  • A monoamine oxidase inhibitor (MAOI) within the past 2 weeks, which is a medicine usually used for depression or Parkinson’s disease
  • An anticholinergic medicine, which includes antihistamines and medicines commonly used for overactive bladder, Parkinson’s disease, or stomach problems
  • Any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, and medicines for anxiety 

This may not be a complete list of medicines that can interact with promethazine. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much promethazine?

If you or someone else has used too much promethazine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of promethazine?

If you miss a dose, use it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only use the next dose. Do not take double or extra doses.