PENTHROX 99.9 % Liquid

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This page is for general information. Consult a doctor for personal advice. Call emergency services if symptoms are severe.
About the medicine

How to use Penthrox

Contents of the leaflet

  1. Package Leaflet: Information for the User
  2. Penthrox, 99.9%, Solution for Inhalation
    1. Read the leaflet carefully before using the medicine, as it contains important information for the patient.
    2. Contents of the Package Leaflet
  3. What is Penthrox and what is it used for
  4. Important information before using Penthrox
    1. When not to use Penthrox:
    2. Warnings and precautions
    3. Use in children and adolescents
    4. Penthrox with other medicines
    5. Penthrox with food, drink, and alcohol
    6. Pregnancy, breastfeeding, and fertility
    7. Driving and using machines
    8. Penthrox contains butylhydroxytoluene (E 321)
  5. How to use Penthrox
    1. Instructions for using Penthrox
    2. Overdose of Penthrox
  6. Side effects
    1. Severe side effects
    2. The above side effects can be life-threatening, so inform your doctor or pharmacist immediately if they occur.
    3. Other side effects
    4. Reporting side effects
  7. How to store Penthrox
  8. Contents of the pack and other information
    1. What Penthrox contains
    2. What Penthrox looks like and contents of the pack
    3. Marketing authorization holder
    4. Manufacturer
    5. This medicine is authorized in the Member States of the European Economic Area and in the United Kingdom (Northern Ireland) under the following names:
    6. Information for medical staff
    7. The doctor, nurse, paramedic, or person trained in the use of Penthrox must provide the patient with the patient information leaflet and familiarize them with its contents.

Package Leaflet: Information for the User

Penthrox, 99.9%, Solution for Inhalation

Methoxyflurane

Read the leaflet carefully before using the medicine, as it contains important information for the patient.

  • Keep this leaflet, you may need to read it again.
  • If you have any further questions, ask your doctor or pharmacist.
  • This medicine has been prescribed for you, do not pass it on to others. It may harm them, even if their symptoms are the same as yours.
  • If you experience any side effects, including those not listed in this leaflet, tell your doctor or pharmacist (see section 4).

Contents of the Package Leaflet

  • 1. What is Penthrox and what is it used for
  • 2. Important information before using Penthrox
  • 3. How to use Penthrox
  • 4. Possible side effects
  • 5. How to store Penthrox
  • 6. Contents of the pack and other information
Doctor consultation

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1. What is Penthrox and what is it used for

Penthrox contains the active substance methoxyflurane. The medicine is indicated for the emergency relief of pain and is inhaled into the lungs through a single-use Penthrox inhaler. Penthrox is intended to reduce the severity of pain, not to completely eliminate it.

2. Important information before using Penthrox

When not to use Penthrox:

  • or if your relatives have experienced severe side effects after using inhaled anesthetic agents;

Penthrox must not be used as an anesthetic agent. If you have any doubts about whether this medicine is suitable for you, consult your doctor or pharmacist.

Warnings and precautions

In the case of patients who are affected by the following points, the use of Penthrox should be discussed with a doctor before starting treatment:

  • patients with kidney or liver disease;
  • patients with conditions that may cause kidney problems;
  • elderly patients.

Depression of breathing has been reported in patients treated with Penthrox, with symptoms such as slow and shallow breathing or other breathing difficulties (section 4). If breathing problems occur, you should immediately inform a medical professional.

Use in children and adolescents

Penthrox should not be used in children and adolescents under 18 years of age.

Penthrox with other medicines

Tell your doctor or pharmacist about all medicines you are taking, or have recently taken, and about any medicines you plan to take, especially those listed below:

  • Isoniazid used to treat tuberculosis.
  • Phenobarbital or carbamazepine used to treat epilepsy.
  • Rifampicin or other antibiotics used to treat infections.
  • Medicines or substances that have a sedative effect on the nervous system, such as narcotics, painkillers, sedatives, sleeping pills, general anesthetics, phenothiazine, anxiolytics, muscle relaxants, and antihistamines with a sedative effect.
  • Antibiotics and other medicines that may have a harmful effect on the kidneys, such as tetracycline, gentamicin, colistin, polymyxin B, and amphotericin, as well as contrast agents.
  • Efavirenz or nevirapine used to treat HIV.

In case of doubts, consult your doctor. If you require hospital treatment with general anesthesia, you should inform the medical staff about the previous use of Penthrox.

Penthrox with food, drink, and alcohol

Do not drink alcohol while using the medicine, as it may enhance the effect of the medicine. You can take food and drinks while using the medicine, unless your doctor or pharmacist decides otherwise.

Pregnancy, breastfeeding, and fertility

If you are pregnant or breastfeeding, think you may be pregnant, or plan to have a child, consult your doctor before using this medicine. Your doctor or pharmacist will discuss with you the possible risks and benefits of using Penthrox.

Driving and using machines

The medicine may affect your ability to drive and use machines. Before driving or using machines, make sure you are able to perform these activities. Penthrox may cause drowsiness and dizziness.

Penthrox contains butylhydroxytoluene (E 321)

Penthrox contains the excipient butylhydroxytoluene (E 321) (0.01% w/w). Butylhydroxytoluene may cause local skin reactions (e.g., contact dermatitis) or eye and mucous membrane irritation.

Medicine questions

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3. How to use Penthrox

This medicine should always be used as directed by your doctor. In case of doubts, consult your doctor or pharmacist. Adults: A single dose may consist of one or two bottles containing 3 ml of Penthrox. The maximum dose is two bottles containing 3 ml of Penthrox. Do not exceed the maximum dose of 6 ml.

Instructions for using Penthrox

Person with a band on their wrist and an inhaler in their mouth with smoke coming out of the mouthpiece
  • 1. The doctor or other medical staff will prepare the inhaler for use and place a security strap on the patient's wrist.
  • 2. The medicine should be inhaled through the inhaler mouthpiece to reduce the severity of pain. In case of doubts, ask the medical staff for help. To get used to the fruity smell of the medicine, the first few breaths should be taken cautiously. Exhale also through the inhaler. After cautious initial breaths, start breathing normally through the inhaler.
Hand holding a pink inhaler to the patient's mouth with the head and shoulder visibleHand holding a pink inhaler with a black mouthpiece, with the hand and fingers visible
  • 3. If stronger pain relief is needed, cover the hole located in the upper part of the transparent carbon chamber with your finger. The medical staff will indicate the location of this hole.
  • 4. It is not necessary to breathe through the inhaler all the time. Medical staff will encourage you to take breaks in inhalation, as this will allow for a longer duration of pain relief.
Inhaler with smoke coming out of the mouthpiece and curled smoke

Medical staff will encourage you to take breaks in inhalation, as this will allow for a longer duration of pain relief.

  • 5. Use the inhalations for as long as the medical staff recommends or until the maximum recommended dose of the medicine is reached.

Do not give the medicine to another person, even if their symptoms are the same.

Overdose of Penthrox

The patient uses the medicine under the supervision of medical staff trained in its administration, so the likelihood of overdose is extremely low. A maximum of two bottles of the medicine can be used at one time. Exceeding the maximum dose of Penthrox may result in kidney damage. If you suspect that you have taken a higher dose than recommended, inform the medical staff immediately. In case of questions or doubts, consult your doctor or pharmacist.

4. Side effects

Like all medicines, Penthrox can cause side effects, although not everybody gets them.

Severe side effects

If you experience any of the following symptoms, tell your doctor or pharmacist immediately:

  • Severe allergic reactions, including symptoms such as breathing difficulties and/or face swelling.
  • Liver symptoms, such as loss of appetite, nausea, vomiting, jaundice (yellowing of the skin and/or eyes), dark urine, pale stools, pain or tenderness in the right side (below the ribcage).
  • Kidney symptoms, such as decreased or increased urination, swelling of the feet or lower legs.
  • Slow and shallow breathing or other breathing difficulties (symptoms of respiratory depression) (frequency cannot be estimated from the available data).

The above side effects can be life-threatening, so inform your doctor or pharmacist immediately if they occur.

Other side effects

Very common(may affect more than 1 in 10 people)

  • Dizziness

Common side effects(may affect up to 1 in 10 people):

  • Drowsiness
  • Headache or nausea
  • Euphoria
  • Feeling of intoxication
  • Taste disturbances
  • Cough

Uncommon side effects(may affect up to 1 in 100 people):

  • Anxiety or depression
  • Attention disturbances
  • Inappropriate emotions or behaviors
  • Repetition of words or difficulties in speaking
  • Memory loss
  • Numbness or tingling in hands and feet
  • Numbness
  • Visual disturbances
  • Redness of the skin
  • Low or high blood pressure
  • Dry mouth
  • Discomfort or itching in the mouth
  • Increased saliva production
  • Increased appetite
  • Vomiting
  • Sweating
  • Fatigue
  • Malaise
  • Chills
  • Feeling of relaxation

Frequency not known(frequency cannot be estimated from the available data):

  • Hypersensitivity
  • Mood disturbances
  • Nervousness or agitation
  • Feeling of detachment from reality
  • Disorientation
  • Altered states of consciousness
  • Choking
  • Shallow breathing
  • Uncontrolled eye movements

Reporting side effects

If you experience any side effects, including those not listed in this leaflet, tell your doctor or pharmacist. Side effects can be reported directly to: Department of Drug Safety Monitoring, Office for Registration of Medicinal Products, Medical Devices, and Biocidal Products, Al. Jerozolimskie 181C, 02-222 Warsaw, tel.: +48 22 49 21 301, fax: +48 22 49 21 309, website: https://smz.ezdrowie.gov.pl. Side effects can also be reported directly to the marketing authorization holder. By reporting side effects, you can help provide more information on the safety of this medicine.

5. How to store Penthrox

Keep the medicine out of the sight and reach of children. Do not use this medicine after the expiry date stated on the packaging after EXP. The expiry date refers to the last day of the month. There are no special precautions for the storage of this medicinal product. The doctor or medical staff will dispose of any remaining Penthrox and the Penthrox inhaler in accordance with local regulations.

6. Contents of the pack and other information

What Penthrox contains

  • The active substance of Penthrox is methoxyflurane. One sealed bottle contains 3 ml of methoxyflurane 99.9%.
  • The other ingredient is: butylhydroxytoluene (E 321).

What Penthrox looks like and contents of the pack

Penthrox is a clear, almost colorless, volatile liquid with a characteristic fruity smell. The medicinal product Penthrox is available in the following packs: 10 bottles of 3 ml, in a cardboard box. 1 or 10 sets. The set includes: one bottle of 3 ml methoxyflurane 99.9%, one Penthrox inhaler, and one carbon chamber with a security lock. The bottle has a capacity of 5 ml, made of orange glass type I, with a PET insert, a POM (polyoxymethylene) screw cap, and a tamper-evident seal. Not all pack sizes may be marketed.

Marketing authorization holder

Medical Developments NED B.V. Strawinskylaan 411, WTC Tower A, 1077 XX Amsterdam, Netherlands

Manufacturer

MIAS Pharma Limited, Suite 1, First Floor, Stafford House, Strand Road, Portmarnock, Co. Dublin, Ireland

This medicine is authorized in the Member States of the European Economic Area and in the United Kingdom (Northern Ireland) under the following names:

Austria: Penthrop, Belgium: Methoxyflurane Medical Developments NED, Croatia: Penthrox, Czech Republic: Penthrox, Denmark: Penthrox, Finland: Penthrox, France: Methoxyflurane Medical Developments NED, Spain: Penthrox, Iceland: Penthrox, Ireland: Methoxyflurane Medical Developments MD&P, Luxembourg: Methoxyflurane Medical Developments NED, Germany: Penthrox, Norway: Penthrox, Poland: Penthrox, Portugal: Penthrox, Slovakia: Penthrox, Slovenia: Penthrox, Sweden: Penthrox, Italy: Penthrox. Date of last revision of the leaflet:05/2023

Information for medical staff

The following information is intended for medical staff only: The instructions below describe the proper preparation of the Penthrox inhaler for use and the correct way to use it.

Penthrox inhaler green with a black carbon chamber and a white element on top
  • 1. Make sure the carbon chamber is placed in the slot at the top of the Penthrox inhaler.
  • 2. Remove the bottle cap manually. Alternatively: use the base of the Penthrox inhaler to loosen the bottle cap – insert it into the base and turn it 180° (half a turn). Separate the inhaler from the bottle and remove the cap manually.
  • 3. Hold the Penthrox inhaler at a 45° angle and pour the entire contents of one bottle of Penthrox into its base, while rotating the inhaler several times around its axis.
Pink coneHand holding the green Penthrox inhaler with a carbon chamber and arrows indicating rotational movement
  • 4. Put the security strap on the patient's wrist. The patient breathes through the Penthrox inhaler mouthpiece to relieve pain. Instruct the patient to take the first breaths through the inhaler cautiously and then start breathing normally.
Hand clasping the pink inhaler with a black filter
  • 5. The patient also exhales into the Penthrox inhaler. The exhaled vapors pass through the carbon chamber to capture any remaining methoxyflurane.
Hand covering the hole in the upper part of the pink carbon chamber of the inhaler
  • 6. If stronger pain relief is needed, the patient (during inhalation) can cover the hole located in the upper part of the carbon chamber with their finger.
Hand holding the pink inhaler with a black carbon chamber
  • 7. If further pain relief is needed after using the first bottle, a second bottle of the medicine can be used, if available. Alternatively, a bottle from a new pack can be used. Prepare for use in the same way as for the previous dose (steps 2 and 3).

There is no need to replace the carbon chamber. Place the used bottle in the included plastic bag.

  • 8. Inform the patient that in order to achieve the desired pain relief effect, they should take breaks in inhalation. Continuous inhalation shortens the duration of pain relief. The patient should use the minimum dose that allows for effective pain control.
Hand holding the Penthrox inhaler over an empty bottle
  • 9. Close the empty medicine bottle. Place the used Penthrox inhaler and the empty bottle in a sealable plastic bag and dispose of them properly.

The doctor, nurse, paramedic, or person trained in the use of Penthrox must provide the patient with the patient information leaflet and familiarize them with its contents.

Online doctors for Penthrox

Discuss questions about Penthrox, including use, safety considerations and prescription review, subject to medical assessment and local regulations.

Doctor
5.0(36)

Andrei Popov

General medicinePain medicine7 years of experience

Dr. Andrei Popov is a family physician with specialized training in the management of chronic pain. He provides video consultations for adults in Spain and across Europe: whether you have been living with pain for months that no one has been able to properly explain, or you need to resolve a health issue without waiting weeks for an appointment.

His approach is clear: to listen, organize your case, and provide you with a practical roadmap based on evidence-based medicine and adapted to your medical history and personal needs.

Pain: how he can help

  • Chronic pain (more than 3 months
  • Migraine and recurrent or high-intensity headaches
  •  Neck, lower back, back and joint pain
  •  Post-traumatic pain after injuries or surgeries
  •  Pain of neurological origin: neuralgia, neuropathic pain, fibromyalgia

General medicine

  • Frequent respiratory infections (cold, flu, persistent cough)
  • Hypertension, diabetes and metabolic disorders
  • Review of laboratory tests and MRI/CT reports (explained in clear language)
  • Preventive medicine and health monitoring
  • Second opinions and treatment adjustments (when clinically appropriate)

What the consultation is like
 Each session lasts up to 30 minutes. We review symptoms, medical history, medications and any tests you provide, and you finish the consultation with a clear treatment plan, defined next steps, and criteria to understand when follow-up may be needed. If warning signs are detected, he will clearly advise whether you need in-person care or urgent medical attention.

Book a video appointment
€86
Doctor
5.0(19)

Nuno Tavares Lopes

Family medicineGeneral medicine18 years of experience

Dr. Nuno Tavares Lopes is a licensed physician in Portugal with 17 years of experience in emergency medicine, family and general practice, and public health. He is the Director of Medical and Public Health Services at an international healthcare network and serves as an external consultant for the WHO and ECDC.

  • Emergency care: infections, fever, chest/abdominal pain, minor injuries, paediatric emergencies
  • Family medicine: hypertension, diabetes, cholesterol, chronic disease management
  • Travel medicine: pre-travel advice, vaccinations, fit-to-fly certificates, travel-related illnesses
  • Sexual and reproductive health: PrEP, STD prevention, counselling, treatment
  • Weight management and wellness: personalised weight loss programmes, lifestyle guidance
  • Skin and ENT issues: acne, eczema, allergies, rashes, sore throat, sinusitis
  • Pain management: acute and chronic pain, post-surgical care
  • Public health: prevention, health screenings, long-term monitoring
  • Sick leave (Baixa médica) connected to Segurança Social in Portugal
  • IMT medical certificates for driving licence exchange
Dr. Nuno Tavares Lopes provides medical support for patients using GLP-1 medications (Mounjaro, Wegovy, Ozempic, Rybelsus) as part of a weight loss strategy. He offers individualised treatment planning, regular follow-up, dose adjustment, and advice on combining medication with sustainable lifestyle changes. Consultations follow the medical standards accepted in Europe.

Dr. Lopes also provides interpretation of medical tests, follow-up care for complex patients, and multilingual support. Whether for urgent concerns or long-term care, he helps patients act with clarity and confidence.

Book a video appointment
€70
Doctor
0.0(0)

Hocine Lokchiri

General medicine21 years of experience

Dr. Hocine Lokchiri is a French consultant with over 20 years of experience in General and Emergency Medicine. He works with adults and children, helping patients with urgent symptoms, infections, sudden health changes and everyday medical concerns that require timely evaluation. His background includes clinical practice in France, Switzerland and the United Arab Emirates, which allows him to navigate different healthcare systems and manage a wide range of conditions with confidence. Patients value his calm, structured approach, clear explanations and evidence-based decision-making.

Online consultations with Dr. Lokchiri are suitable for many situations when someone needs quick medical guidance, reassurance or a clear next step. Common reasons for booking include:

  • fever, chills, fatigue and viral symptoms
  • cough, sore throat, nasal congestion, breathing discomfort
  • bronchitis and mild asthma flare-ups
  • nausea, diarrhoea, abdominal pain, digestive infections
  • rashes, allergic reactions, redness, insect bites
  • muscle or joint pain, mild injuries, sprains
  • headache, dizziness, migraine symptoms
  • stress-related symptoms, sleep disturbances
  • questions about test results and treatment plans
  • management of chronic conditions in stable phases
Many patients reach out when symptoms appear suddenly and cause concern, when a child becomes unwell unexpectedly, when a rash changes or spreads, or when it’s unclear whether an in-person examination is necessary. His emergency medicine background is particularly valuable online, helping patients understand risk levels, identify warning signs and choose safe next steps.

Some situations are not suitable for online care. If a patient has loss of consciousness, severe chest pain, uncontrolled bleeding, seizures, major trauma or symptoms suggesting a stroke or heart attack, he will advise seeking immediate local emergency services. This improves safety and ensures patients receive the right level of care.

Dr. Lokchiri’s professional training includes:

  • Advanced Trauma Life Support (ATLS)
  • Basic and Advanced Cardiac Life Support (BLS/ACLS)
  • Pediatric Advanced Life Support (PALS)
  • Prehospital Trauma Life Support (PHTLS)
  • eFAST and critical care transthoracic echocardiography
  • aviation medicine
He is an active member of several professional organisations, including the French Society of Emergency Medicine (SFMU), the French Association for Emergency Physicians (AMUF) and the Swiss Society of Emergency and Rescue Medicine (SGNOR). In consultations, he works with clarity and precision, helping patients understand their symptoms, possible risks and the safest treatment options.
Book a video appointment
€64

Get Penthrox Prescription Online

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4

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Electronic prescription sent to your email — valid across Spain.

Frequently Asked Questions

Is a prescription required for Penthrox?

Penthrox requires a prescription in Poland. You can check with a doctor online whether this medicine may be appropriate for your situation.

What is the active substance in Penthrox?

The active ingredient in Penthrox is methoxyflurane. This information helps identify medicines with the same composition but different brand names.

Who manufactures Penthrox?

Penthrox is manufactured by MIAS Pharma Limited. Pharmacy brands and packaging may differ depending on the distributor.

Which doctors can assess the use of Penthrox online?

Doctors such as Family doctors, Psychiatrists, Dermatologists, Cardiologists, Endocrinologists, Gastroenterologists, Pulmonologists, Nephrologists, Rheumatologists, Hematologists, Infectious disease physicians, Allergists, Geriatricians, Paediatricians, Oncologists may assess whether Penthrox is appropriate, depending on your situation and local regulations. You can book an online consultation to discuss your symptoms and possible next steps.

How to buy Penthrox in Spain?

Spain has a well-developed healthcare infrastructure across major cities such as Madrid, Barcelona, Valencia, and Seville. Pharmacies are widely available and operate under strict regulations, ensuring access to prescribed medications.

You can buy Penthrox in Madrid, Barcelona, Seville, or Valencia at any local pharmacy with a valid prescription.

To obtain a prescription, you can use Oladoctor:

What are the alternatives to Penthrox?

Other medicines with the same active substance (methoxyflurane) include Nefopam Holsten, Nefopam Ielfa, Sativex. These may have different brand names or formulations but contain the same therapeutic ingredient. Always consult a doctor before switching or starting a new medicine.

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