Generic name: promethazine (oral) [ pro-METH-a-zeen ]
Brand name: Phenergan
Drug classes: Antihistamines, Phenothiazine antiemetics

Medically reviewed by Melisa Puckey, BPharm. Last updated on Feb 29, 2024.

What is promethazine?

Promethazine is in a group of drugs called phenothiazines (FEEN-oh-THYE-a-zeens). It works by changing the actions of chemicals in your brain. Promethazine also acts as an antihistamine. It blocks the effects of the naturally occurring chemical histamine in your body.

Promethazine is used to treat allergy symptoms such as itching, runny nose, sneezing, itchy or watery eyes, hives, and itchy skin rashes. It also prevents motion sickness, and treats nausea and vomiting or pain after surgery. It is also used as a sedative or sleep aid.

Promethazine is not for use in treating symptoms of asthma, pneumonia, or other lower respiratory tract infections.

Warnings

Stop using promethazine and call your doctor at once if you have twitching or uncontrollable movements of your eyes, lips, tongue, face, arms, or legs. These could be early signs of dangerous side effects. Promethazine should not be given to a child younger than 2 years old. Promethazine can cause severe breathing problems or death in a child in very young children. Carefully follow your doctor's instructions when giving this medicine to a child of any age.

Promethazine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert. Avoid drinking alcohol, which can increase some of the side effects of promethazine. There are many other medicines that can interact with promethazine. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor. Keep a list with you of all the medicines you use and show this list to any doctor or other healthcare provider who treats you.

Before taking this medicine

Promethazine should not be given to a child younger than 2 years old. Promethazine can cause severe breathing problems or death in very young children. Carefully follow your doctor's instructions when giving this medicine to a child of any age.

You should not take this medicine if you are allergic to promethazine or to similar medicines such as chlorpromazine, fluphenazine, mesoridazine, perphenazine, prochlorperazine, thioridazine, or trifluperazine.

To make sure promethazine is safe for you, tell your doctor if you have:

• asthma, chronic obstructive pulmonary disease (COPD), sleep apnea, or other breathing disorder;

• a sulfite allergy;

• a history of seizures;

• a weak immune system (bone marrow depression);

• glaucoma;

• enlarged prostate or problems with urination;

• stomach ulcer or obstruction;

• heart disease or high blood pressure;

• liver disease;

• adrenal gland tumor (pheochromocytoma);

• low levels of calcium in your blood (hypocalcemia); or

• if you have ever had a serious side effect while using promethazine or any other phenothiazine.

It is not known whether promethazine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

It is not known whether promethazine passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

How should I take promethazine?

Take promethazine exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Promethazine is often taken at bedtime or before meals. For motion sickness, promethazine is usually started within 1 hour before traveling. When used for surgery, promethazine is usually taken the night before the surgery.

How often you take this medicine and the timing of your dose will depend on the condition being treated.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

If a child is using this medicine, tell your doctor if the child has any changes in weight. Promethazine doses are based on weight in children, and any changes may affect your child's dose.

Call your doctor if your symptoms do not improve, or if they get worse while using promethazine.

This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using promethazine.

Store at room temperature away from moisture, heat, and light.

Related/similar drugs

prednisone, trazodone, hydroxyzine, ondansetron, clonazepam, fluticasone nasal, lorazepam, cetirizine, loratadine, diazepam

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include overactive reflexes, loss of coordination, severe drowsiness or weakness, fainting, dilated pupils, weak or shallow breathing, or seizure (convulsions).

What to avoid

This medicine may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

Drinking alcohol can increase certain side effects of promethazine.

Avoid exposure to sunlight or tanning beds. Promethazine can make you sunburn more easily. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

Promethazine side effects

Get emergency medical help if you have any signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using promethazine and call your doctor at once if you have:

• severe drowsiness, weak or shallow breathing;

• a light-headed feeling, like you might pass out;

• confusion, agitation, hallucinations, nightmares;

• seizure (convulsions);

• fast or slow heartbeats;

• jaundice (yellowing of the skin or eyes);

• uncontrolled muscle movements in your face (chewing, lip smacking, frowning, tongue movement, blinking or eye movement);

• easy bruising or bleeding (nosebleeds, bleeding gums);

• sudden weakness or ill feeling, fever, chills, sore throat, mouth sores, red or swollen gums, trouble swallowing; or

• severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Side effects such as confusion and severe drowsiness may be more likely in older adults.

Common promethazine side effects may include:

• drowsiness, dizziness;

• ringing in your ears;

• double vision;

• feeling nervous;

• dry mouth; or

• tired feeling, sleep problems (insomnia).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect promethazine?

Cold or allergy medicine, sedatives, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression or anxiety can interact with promethazine and cause medical problems or increase side effects. Tell your doctor if you regularly use any of these medicines.

Also tell your doctor if you are using any of the following medicines:

• lithium (Eskalith, Lithobid);

• atropine (Atreza, Sal-Tropine), belladonna (Donnatal, and others), benztropine (Cogentin), dimenhydrinate (Dramamine), methscopolamine (Pamine), or scopolamine (Transderm-Scop);

• blood pressure medication such as guanadrel (Hylorel), guanethidine (Ismelin), propranolol (Inderal), and others;

• a blood thinner such as warfarin (Coumadin);

• bronchodilators such as ipratropium (Atrovent) or tiotropium (Spiriva);

• bladder or urinary medications such as oxybutynin (Ditropan, Oxytrol), solifenacin (Vesicare), and others;

• an MAO inhibitor such as isocarboxazid (Marplan), tranylcypromine (Parnate), phenelzine (Nardil), or selegiline (Eldepryl, Emsam); or

• medicines to treat Parkinson's disease, restless leg syndrome, or pituitary gland tumor (prolactinoma); or

• medicine to treat stomach ulcer or irritable bowel syndrome, such as dicyclomine (Bentyl), glycopyrrolate (Robinul), hyoscyamine (Anaspaz, Cystospaz, Levsin, and others), mepenzolate (Cantil), or propantheline (Pro-Banthine).

This list is not complete and there are many other medicines that can interact with promethazine. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor. Keep a list with you of all the medicines you use and show this list to any doctor or other healthcare provider who treats you.

Frequently asked questions

• Par promethazine with codeine vs Hi-Tech promethazine with codeine?
• How long does promethazine stay in your system?

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use promethazine only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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