Promethazine and Dextromethorphan

This information from Lexicomp^® explains what you need to know about this medication, including what it’s used for, how to take it, its side effects, and when to call your healthcare provider.

What is this drug used for?

• It is used to relieve coughing.
• It is used to ease allergy signs.
• It is used to ease cold signs.

What do I need to tell my doctor BEFORE I take this drug?

• If you are allergic to this drug; any part of this drug; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
• If you have any of these health problems: Asthma or other breathing problems like COPD (chronic obstructive pulmonary disease) or sleep apnea (breathing problems during sleep).
• If you have a cough with a lot of mucus, a long-term cough caused by smoking or being around smoke, or lung problems like asthma or emphysema.
• If you have taken certain drugs for depression or Parkinson’s disease in the last 14 days. This includes isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline. Very high blood pressure may happen.
• If you are taking any of these drugs: Linezolid or methylene blue.

This is not a list of all drugs or health problems that interact with this drug.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take this drug?

• Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
• Do not take more than what your doctor told you to take. Taking more than you are told may raise your chance of severe side effects.
• Do not take this drug for longer than you were told by your doctor.
• Avoid driving and doing other tasks or actions that call for you to be alert until you see how this drug affects you.
• This drug may affect certain lab tests. Tell all of your health care providers and lab workers that you take this drug.
• If you have high blood sugar (diabetes), you will need to watch your blood sugar closely.
• This drug may cause the results of some pregnancy tests to be wrong. Talk with the doctor.
• Talk with your doctor before you use alcohol, marijuana or other forms of cannabis, or prescription or OTC drugs that may slow your actions.
• You may get sunburned more easily. Avoid sun, sunlamps, and tanning beds. Use sunscreen and wear clothing and eyewear that protects you from the sun.
• This drug may raise the chance of seizures in some people, including people who have had seizures in the past. Talk to your doctor to see if you have a greater chance of seizures while taking this drug.
• If you are 65 or older, use this drug with care. You could have more side effects.
• Tell your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding. You will need to talk about the benefits and risks to you and the baby.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of high or low blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
• Fast or slow heartbeat.
• Trouble passing urine.
• Trouble controlling body movements, twitching, change in balance, trouble swallowing or speaking.
• Shakiness.
• Hallucinations (seeing or hearing things that are not there).
• Mood changes.
• Ringing in ears.
• Seizures.
• Any unexplained bruising or bleeding.
• Change in eyesight.
• Feeling nervous and excitable.
• Trouble sleeping.
• Yellow skin or eyes.
• A very bad and sometimes deadly health problem called neuroleptic malignant syndrome (NMS) may happen. Call your doctor right away if you have any fever, muscle cramps or stiffness, dizziness, very bad headache, confusion, change in thinking, fast heartbeat, heartbeat that does not feel normal, or are sweating a lot.
• This drug may cause very bad and sometimes deadly breathing problems. Call your doctor right away if you have slow, shallow, or trouble breathing.
• Low white blood cell counts have rarely happened with this drug. This may lead to a higher chance of getting an infection. Tell your doctor if you have ever had a low white blood cell count. Call your doctor right away if you have signs of infection like fever, chills, or sore throat.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Feeling dizzy, sleepy, tired, or weak.
• Dry mouth.
• Upset stomach or throwing up.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to your national health agency.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

How is this drug best taken?

Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.

• Take with or without food. Take with food if it causes an upset stomach.
• Measure liquid doses carefully. Use the measuring device that comes with this drug. If there is none, ask the pharmacist for a device to measure this drug.
• Do not use a household teaspoon or tablespoon to measure this drug. Doing so could lead to the dose being too high.

What do I do if I miss a dose?

• If you take this drug on a regular basis, take a missed dose as soon as you think about it.
• If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
• Do not take 2 doses at the same time or extra doses.
• Many times this drug is taken on an as needed basis. Do not take more often than told by the doctor.

How do I store and/or throw out this drug?

• Store at room temperature protected from light. Store in a dry place. Do not store in a bathroom.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

General drug facts

• If your symptoms or health problems do not get better or if they become worse, call your doctor.
• Do not share your drugs with others and do not take anyone else’s drugs.
• Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
• Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
• If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This generalized information is a limited summary of diagnosis, treatment, and/or medication information. It is not meant to be comprehensive and should be used as a tool to help the user understand and/or assess potential diagnostic and treatment options. It does NOT include all information about conditions, treatments, medications, side effects, or risks that may apply to a specific patient. It is not intended to be medical advice or a substitute for the medical advice, diagnosis, or treatment of a health care provider based on the health care provider’s examination and assessment of a patient’s specific and unique circumstances. Patients must speak with a health care provider for complete information about their health, medical questions, and treatment options, including any risks or benefits regarding use of medications. This information does not endorse any treatments or medications as safe, effective, or approved for treating a specific patient. UpToDate, Inc. and its affiliates disclaim any warranty or liability relating to this information or the use thereof. The use of this information is governed by the Terms of Use, available at https://www.wolterskluwer.com/en/know/clinical-effectiveness-terms.

Last Reviewed Date

2024-10-21

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