Methoxyflurane

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.

Brand Names: Canada

Penthrox

What is this drug used for?

• It is used to manage pain.
• This drug is not for use with long-term pain or pain that goes away and keeps coming back. Talk with your doctor.

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: Blood pressure problems, breathing problems, heart disease, or kidney disease.
• If you have a health problem or take a drug that makes you very sleepy.
• If you have had a recent head injury.
• If you have recently drunk a lot of alcohol or taken a drug that may slow your actions like phenobarbital or some pain drugs like oxycodone.
• If you or a family member have had malignant hyperthermia. Signs of this health problem include a very high fever, a fast heartbeat, muscle spasms or stiffness, and trouble breathing.
• If you have had liver problems after getting an anesthetic.
• If you are taking any of these drugs: Isoniazid, phenobarbital, or rifampicin.
• If you are taking any drugs that can raise the chance of kidney problems. There are many drugs that can do this. Ask your doctor or pharmacist if you are not sure.
• If you are pregnant or plan to get pregnant.
• If the patient is a child. Do not give this drug to a child.

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.
• Avoid driving and doing other tasks or actions that call for you to be alert until the effects of this drug wear off and you feel fully awake.
• This drug may be abused. It may be habit-forming.
• Do not take this drug for longer than you were told by your doctor.
• Avoid alcohol, marijuana or other forms of cannabis, or prescription or OTC drugs that may slow your actions.
• If you are 65 or older, use this drug with care. You could have more side effects.
• Tell your doctor if you are breast-feeding. You will need to talk about any risks to your 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 kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.
• Signs of liver problems like dark urine, tiredness, decreased appetite, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
• Severe dizziness or passing out.
• Slow heartbeat.
• Mood changes.
• Memory problems or loss.
• Not able to focus.
• Change in balance.
• This drug may cause a severe and sometimes deadly problem called malignant hyperthermia. Call your doctor right away if you have a fast or abnormal heartbeat, fast breathing, fever, spasm or stiffness of the jaw muscles, blue or gray skin, patchy skin, or unexplained bruising or bleeding. Call your doctor right away if you have signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.

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 or sleepy.
• Headache.
• Upset stomach.

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.

How is this drug best taken?

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

• For breathing in only by an inhaler into the lungs.
• Do not get this drug in your eyes. It may cause irritation. If you get it in your eyes, rinse right away with water.

What do I do if I miss a dose?

• This drug will be given in a health care setting.

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

• This drug will be given in a hospital or doctor’s office. You will not store it at home.

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

2024-06-03

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