Pethidine
Pronunciation: PETH-ih-deen (US generic name: meh-PER-ih-deen).
- Generic name
- pethidine (US: meperidine)
- Drug class
- Opiate (narcotic) analgesic; Schedule II controlled substance in the United States
- Form
- Tablet; Syrup (liquid)
- Route
- Oral
- Legal status
- Prescription-only medicine; Schedule II controlled substance (United States).
Availability and supply rules vary by country
Trade names by country: United States · United Kingdom
Australia: · Full directory
Boxed warning: Addiction, life-threatening respiratory depression, accidental ingestion, and dangerous drug interactions
Pethidine (meperidine) carries the FDA boxed warning applied to opioid analgesics: (1) it exposes patients to the risks of addiction, abuse, and misuse, which can lead to overdose and death — risk should be assessed before starting and reassessed regularly; (2) serious, life-threatening, or fatal respiratory depression may occur, especially when starting treatment or after a dose increase; (3) accidental ingestion, especially by children, can result in a fatal overdose; (4) taking pethidine together with benzodiazepines or other central nervous system depressants (including alcohol) can cause profound sedation, respiratory depression, coma, and death. (1)
What pethidine (US: meperidine) is and how it works
Pethidine is an opiate (narcotic) analgesic used for relief of severe pain. (3)
Pethidine may be habit forming. Take exactly as directed. It can cause serious or life-threatening breathing problems, especially during the first 24 to 72 hours of treatment and any time the dose is increased. Do not drink alcohol or take other medications that cause drowsiness without consulting a clinician. Do not drive or operate machinery until you know how pethidine affects you, since it can cause drowsiness, dizziness, or fainting.
Mechanism of action: how pethidine (US: meperidine) works
Pethidine (meperidine) is an opioid analgesic producing analgesia, sedation, and respiratory depression; it is hepatically metabolised, partly to normeperidine, an active metabolite with proconvulsant activity that can accumulate with prolonged or high-dose use or in renal impairment, increasing seizure risk. (3) (1) (2)
What pethidine (US: meperidine) is used for
Relief of severe pain
Pethidine is used for relief of severe pain, for which alternative treatments are inadequate. It is an opiate (narcotic) analgesic and should be taken exactly as directed to minimise risks of habit formation, respiratory depression, and other serious side effects. It is not approved for long-term chronic pain use in the United States, due to accumulation of an active metabolite (normeperidine) that raises seizure risk. (3) (1)
Obstetric analgesia and anaesthesia premedication (United Kingdom)
In the United Kingdom, pethidine is also indicated for obstetric analgesia (pain relief during labour) and as premedication and analgesia during anaesthesia. This use is specific to UK product information; the US label covers general severe-pain management only and does not describe these specific uses. (2)
Before taking pethidine (US: meperidine)
Do not take / not appropriate for
- Do not take pethidine if you have taken or are taking any of the following medications within the past two weeks: isocarboxazid, linezolid, methylene blue, phenelzine, selegiline, or tranylcypromine (MAOIs). This combination can cause a dangerous interaction. (all products) (3)
- Do not take pethidine if you have slowed breathing, asthma, COPD, or other lung problems, paralytic ileus, pheochromocytoma, or a history of arrhythmias (fast or irregular heartbeat). Also avoid if you have a brain tumour, increased intracranial pressure, or a seizure disorder. (all products) (3)
- Do not take pethidine if you have significant respiratory depression, acute or severe asthma that is not being monitored in a setting with resuscitation equipment, a known or suspected bowel obstruction (paralytic ileus), or a comatose state. (all products) (1) (2)
- Head injury, raised pressure inside the skull, and severe liver or kidney impairment are also reasons pethidine should generally be withheld — tell your prescriber if any of these apply to you. (all products) (2)
Tell your clinician about
- Any allergies to meperidine, pethidine, or other substances.
- All medications you are taking, including prescription, over-the-counter, herbal (especially St. John's wort and tryptophan), and street drugs.
- If you have or have ever had: slowed breathing, asthma, COPD, other lung disease, paralytic ileus, pheochromocytoma, arrhythmias, brain tumour, increased intracranial pressure, seizures, thyroid, pancreas, gallbladder, heart, liver, or kidney disease.
- If you are pregnant, planning to become pregnant, or breastfeeding.
- If you drink alcohol or use any recreational drugs.
- If you are planning to drive or operate machinery – pethidine may cause drowsiness, dizziness, and fainting.
How to take pethidine (US: meperidine)
- Take pethidine exactly as directed by your doctor. It is usually taken with or without food every 3 to 4 hours as needed for pain.
- Swallow tablets whole; do not chew or crush them.
- For the syrup (liquid), use a dose-measuring spoon or cup (not a household spoon) and mix each dose with half a glass of water.
- Your doctor may adjust your dose based on pain control and side effects.
- If you have taken pethidine for longer than a few weeks, do not stop taking it suddenly without talking to your doctor. The dose should be gradually reduced.
- Talk to your doctor or pharmacist about access to rescue medicines (naloxone or nalmefene) while taking pethidine.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (3) (1) (2)
Missed dose
This medication is usually taken as needed. If your doctor has told you to take pethidine regularly, take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and continue your regular schedule. Do not take a double dose to make up for a missed one. If you are unsure, ask your pharmacist or prescriber.
Overdose
If overdose is suspected, call Poison Control (1-800-222-1222) or go to poisonhelp.org. If the person has collapsed, is having a seizure, or is unresponsive, call 911 immediately. Symptoms of overdose include slow or shallow breathing, difficulty breathing, extreme sleepiness (unable to respond or wake), cold clammy skin, slow heartbeat, and narrowed or widened pupils. If naloxone is available, give the first dose, call 911, stay and watch closely; additional doses may be given every 2–3 minutes if symptoms return before medical help arrives. (3)
Side effects
Pethidine can cause several side effects. Common effects include nausea, vomiting, sweating, decreased sexual desire, and erectile dysfunction. Serious side effects may occur, including life-threatening respiratory depression and serotonin syndrome.
Nausea, vomiting, sweating
What to notice: Nausea, vomiting, or increased sweating, especially at the start of treatment or after a dose increase.
What to do: Tell your doctor if these are persistent or severe. (3)
Decreased sexual desire or erectile dysfunction
What to notice: Loss of interest in sex or difficulty achieving or maintaining an erection.
What to do: Discuss with your doctor if this becomes bothersome. (3)
Respiratory depression
What to notice: Unusual snoring or long pauses between breaths during sleep, slowed breathing, shortness of breath, or extreme drowsiness.
What to do: Contact your doctor immediately or seek emergency care. This can be life-threatening. (3)
Serotonin syndrome
What to notice: Agitation, hallucinations, fever, sweating, confusion, fast heartbeat, shivering, severe muscle stiffness or twitching, loss of coordination, nausea, vomiting, or diarrhoea.
What to do: Seek immediate medical attention. This can be life-threatening. (3)
Opioid-induced hyperalgesia
What to notice: New or increased pain, or pain from ordinary touch or tasks (such as combing hair).
What to do: Contact your doctor promptly; do not increase the dose on your own. (3)
Seizures or arrhythmias
What to notice: Seizures, chest pain, palpitations, or irregular heartbeat.
What to do: Seek emergency medical attention. (3)
Allergic reaction
What to notice: Rash, hives, facial swelling, difficulty breathing or swallowing.
What to do: Seek emergency medical attention immediately; a clinician or emergency service will decide whether Pethidine needs to be stopped. (3)
Serious warnings
Habit formation and misuse — warning
Symptoms: Craving, inability to control use, taking more than prescribed, or using for non-medical purposes.
Action: Take pethidine exactly as directed. Do not share with others. Report any concerns to your doctor. (3)
Respiratory depression — emergency
Symptoms: Unusual snoring or long pauses between breaths during sleep, slowed or shallow breathing, difficulty breathing, extreme drowsiness.
Action: Seek emergency medical help immediately. Give naloxone if available and call 911. (3)
Serotonin syndrome — emergency
Symptoms: Agitation, hallucinations, fever, sweating, confusion, fast heartbeat, shivering, severe muscle stiffness or twitching, loss of coordination, nausea, vomiting, diarrhoea.
Action: Seek emergency medical attention immediately. (3)
Accidental ingestion risk — emergency
Symptoms: Especially in children: overdose symptoms including slowed breathing, extreme sleepiness, cold clammy skin, slow heartbeat.
Action: Keep pethidine out of reach of others, especially children. If accidental ingestion occurs, call 911 or Poison Control immediately. (3)
Neonatal withdrawal syndrome — warning
Symptoms: In babies born to mothers who used pethidine regularly during pregnancy: life-threatening withdrawal symptoms after birth.
Action: Discuss pregnancy plans with your doctor before taking pethidine. If pregnant and taking pethidine, inform your obstetrician. (3)
Opioid-induced hyperalgesia — warning
Symptoms: New or increased pain, or pain from ordinarily non-painful stimuli (allodynia).
Action: Contact your doctor; do not increase the dose on your own. (3)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| MAOIs (isocarboxazid, linezolid, methylene blue, phenelzine, selegiline, tranylcypromine) | Concurrent use or use within the past 2 weeks is contraindicated due to risk of serotonin syndrome or other severe reactions. | Do not take pethidine if you have taken these medications within the last 2 weeks. (3) |
| St. John's wort and tryptophan | May increase the risk of serotonin syndrome when taken with pethidine. | Inform your doctor if you use these supplements; avoid combining without medical advice. (3) |
| Alcohol and other CNS depressants (e.g., sedatives, tranquilizers, street drugs) | Combined use can lead to severe respiratory depression, sedation, coma, or death. | Do not drink alcohol while taking pethidine. Tell your doctor about all other medications and substances you use. (3) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy and breastfeeding
Regular use of pethidine during pregnancy may cause life-threatening withdrawal symptoms in the newborn. Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. The benefits and risks should be carefully discussed. (3)
Fertility
Pethidine may decrease fertility in men and women. Discuss fertility concerns with your doctor. (3)
Elderly
Older adults should generally start at a lower dose — the initial oral dose should not exceed 50 mg — and be monitored closely, since sensitivity to sedation and respiratory depression can be greater in this age group. (2)
Renal or hepatic impairment
Severe kidney or liver impairment is a reason pethidine is generally withheld, since reduced clearance can raise levels of pethidine and its normeperidine metabolite, increasing the risk of seizures and other serious effects. Tell your prescriber about any kidney or liver disease. (2)
Children
This page does not cover paediatric dosing. Any use in children must be directed and dosed by a specialist prescriber; do not estimate a child's dose from an adult dose. (1)
Monitoring
Before starting
- Assess for allergies to meperidine or other substances.
- Check for concurrent or recent (within 2 weeks) use of MAOIs.
- Evaluate respiratory status, including any history of slowed breathing, asthma, COPD, or other lung conditions.
- Assess for presence of paralytic ileus, pheochromocytoma, arrhythmias, brain tumour, increased intracranial pressure, seizures, and thyroid/pancreas/gallbladder/heart/liver/kidney disease.
- Discuss pregnancy and breastfeeding status.
- Review all medications, including over-the-counter, herbal (St. John's wort, tryptophan), alcohol, and recreational drug use.
- Educate about the risks of habit formation, respiratory depression, and driving/operating machinery.
During treatment
- Monitor for signs of respiratory depression, especially during the first 24–72 hours and after dose increases.
- Watch for serotonin syndrome symptoms, especially if other serotonergic agents are used.
- Assess for opioid-induced hyperalgesia if pain pattern changes.
- Monitor for constipation and manage with appropriate measures.
- Evaluate the need for rescue naloxone/nalmefene and ensure patient/caregiver knows how to use it.
- If discontinuing after long-term use, gradually taper the dose to avoid withdrawal symptoms.
- Reassess pain control and side effects regularly.
Storage
Store pethidine in its original container, tightly closed, out of reach of children and other people. Keep at room temperature, away from heat and moisture (do not store in the bathroom). Dispose of unused medication through a medicine take-back program. If no take-back program is available, the FDA flush list permits flushing tablets and solution down the toilet.
Professional information
Clinician-facing context only. Use current local prescribing information and clinical guidelines for dosing and monitoring.
United States (FDA label)
Indication: Management of pain severe enough to require an opioid analgesic, for which alternative treatments are inadequate; not approved for chronic pain due to normeperidine metabolite accumulation risk.
Dose summary: Initiate 50-150 mg orally every 3-4 hours as needed, at the lowest effective dose.
Renal context: Not specifically quantified in the US label; UK SmPC withholds pethidine in severe hepatic or renal impairment due to normeperidine/pethidine accumulation risk. (1)
United Kingdom (SmPC)
Indication: Obstetric analgesia; moderate to severe pain; premedication and analgesia during anaesthesia.
Dose summary: Normal single oral dose 50-150 mg, usually not repeated more often than four-hourly. Elderly: initial dose should not exceed 50 mg orally.
Renal context: Withhold in severe hepatic or renal impairment. (2)
Hepatic guidance
Severe hepatic impairment is a reason pethidine is generally withheld, since reduced hepatic clearance can raise pethidine and normeperidine levels; use current local prescribing information and clinical judgement.
Overdose note
Overdose requires immediate attention: support airway and breathing, give naloxone if available, call 911. Symptoms include slow/shallow breathing, extreme sleepiness, cold clammy skin, slow heartbeat. Naloxone may need to be repeated every 2–3 minutes if symptoms return. (3) (1) (2)
Frequently asked questions
Can I drink alcohol while taking pethidine?
No. Drinking alcohol while taking pethidine increases the risk of life-threatening breathing problems, sedation, or coma. Avoid alcohol completely. (3)
Can I drive or operate machinery while taking pethidine?
No. Pethidine may make you drowsy, dizzy, or lightheaded. Do not drive or operate machinery until you know how the medication affects you. (3)
What should I do if I miss a dose?
If you take pethidine regularly and miss a dose, take it as soon as you remember. If it is almost time for the next dose, skip the missed dose and continue your regular schedule. Do not double the dose. (3)
How should I dispose of unused pethidine?
Use a medicine take-back program. If no program is available, the FDA flush list allows flushing tablets and solution down the toilet. Always keep out of reach of children and others. (3)
What are the signs of an overdose?
Slow or shallow breathing, difficulty breathing, extreme sleepiness (unable to wake), cold clammy skin, slow heartbeat, narrowed or widened pupils. If overdose is suspected, give naloxone if available and call 911 immediately. (3)
What is the mechanism of action of pethidine (US: meperidine)?
Pethidine (meperidine) is an opioid analgesic producing analgesia, sedation, and respiratory depression; it is hepatically metabolised, partly to normeperidine, an active metabolite with proconvulsant activity that can accumulate with prolonged or high-dose use or in renal impairment, increasing seizure risk. (3) (1) (2)
References
- Meperidine Hydrochloride tablet — prescribing informationDailyMed, U.S. National Library of Medicine (FDA-approved generic label) · United States · accessed 2026-07-26 · source 1
- Pethidine 50 mg Tablets — Summary of Product Characteristics (SmPC)electronic Medicines Compendium (UK) — Summary of Product Characteristics (Martindale Pharma, an Ethypharm Group Company) · United Kingdom · accessed 2026-07-26 · source 2
- Meperidine (Pethidine)MedlinePlus, U.S. National Library of Medicine (patient-facing monograph) · United States · accessed 2026-07-23 · source 3
Brand names by country
Single-ingredient pethidine (US: meperidine) names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Generic only (meperidine hydrochloride). The former brand Demerol is confirmed discontinued/no longer on the market per MedlinePlus; do not present it as a current brand. (3)verified live fetched 2026-07-27
United Kingdom
- Generic only (marketed as "Pethidine" tablets/injection by Martindale Pharma and ADVANZ Pharma); no proprietary brand name found. (2)verified live fetched 2026-07-27