Short answer: Meperidine (Demerol), called pethidine outside the US, is a synthetic opioid for short-term acute pain. It is a Schedule II controlled substance. It is now rarely used because a breakdown product can cause seizures and because it can be fatal with MAO inhibitor antidepressants.
Key takeaways
- What it is: Meperidine is a synthetic opioid agonist and a Schedule II controlled substance in the US.
- Main uses: Acute pain (short term).
- Timing: effects start in 15 to 45 minutes and last 2 to 4 hours.
- Most dangerous mix: Benzodiazepines (alprazolam, diazepam, clonazepam), which can cause profound sedation, slowed breathing, coma, death.
- Naloxone: it reverses an overdose (not the seizures).
- Dependence risk: High.
- Legal route: only with a prescription from a DEA-registered clinician, filled by a licensed pharmacy.
What is meperidine?
Meperidine is approved for acute pain severe enough to require an opioid. Its injection is used before and during surgery, and in labor, though safer opioids have largely replaced it.
Guidelines advise against meperidine for chronic pain and in older adults. With repeated doses it builds up a metabolite, normeperidine, that irritates the nervous system and can cause tremor, twitching, agitation, and seizures, especially in people with kidney disease.
Quick facts
| Fact | Meperidine |
|---|---|
| Generic name | Meperidine hydrochloride |
| Brand names | Demerol |
| Other names | Pethidine |
| Drug class | Synthetic opioid agonist (phenylpiperidine) |
| US legal status | Schedule II, prescription only |
| Approved uses | Acute pain severe enough to require an opioid; before and during surgery and labor (injection) |
| Forms | Tablets, oral solution, injection |
| Onset | 15 to 45 minutes |
| Half-life | 3 to 5 hours; its metabolite normeperidine lasts 15 to 30 hours |
How long does meperidine last?
- Starts working: 15 to 45 minutes
- Effects last: 2 to 4 hours
- Half-life: 3 to 5 hours; its metabolite normeperidine lasts 15 to 30 hours
Timing varies with the dose, the form, how it is taken, liver and kidney function, age, and other drugs taken at the same time.
What are the biggest risks of meperidine?
The FDA requires boxed warnings, its strongest, on meperidine products, including:
- Addiction, abuse, and misuse, which can lead to overdose and death.
- Life-threatening slowed breathing, especially when starting treatment or after a dose increase.
- Accidental ingestion, especially by children, can cause a fatal overdose.
- Use with benzodiazepines or other central nervous system depressants, including alcohol, can cause profound sedation, slowed breathing, coma, and death.
Common side effects include lightheadedness, dizziness, sedation, nausea, vomiting, and sweating.
Normeperidine toxicity: shakiness, muscle twitching, agitation, and seizures can occur with high doses, repeated dosing, or kidney impairment. Naloxone does not reverse these effects.
Serotonin syndrome: meperidine has serotonin activity. The 1984 death of Libby Zion, who received meperidine while taking an MAO inhibitor, led to major reforms in US hospital training.
What should you never mix with meperidine?
| Combined with | What happens | Label guidance |
|---|---|---|
| Benzodiazepines (alprazolam, diazepam, clonazepam) | Profound sedation, slowed breathing, coma, death | Boxed warning; avoid unless no alternative |
| Alcohol | Stronger sedation and slowed breathing | Avoid |
| Gabapentin, pregabalin, sleep medicines, muscle relaxants | Additive sedation and breathing problems | Use caution; lower doses |
| MAO inhibitors (phenelzine, tranylcypromine, selegiline, linezolid) | Coma, high fever, blood pressure swings, death | Contraindicated, including within 14 days |
| SSRIs, SNRIs, tricyclics, triptans | Serotonin syndrome | Use caution |
| Ritonavir, phenytoin | More normeperidine and seizure risk | Avoid |
Check any combination with the DoseUses combination checker or ask a pharmacist.
What are the signs of a meperidine overdose, and what should you do?
Meperidine overdose causes slow or stopped breathing, pinpoint pupils, and unconsciousness. It can also cause tremor and seizures from normeperidine, which may continue after naloxone restores breathing.
If someone may have overdosed
- Call 911 if the person is unresponsive, cannot be woken, has blue or gray lips, or is breathing slowly or not at all.
- Give naloxone (Narcan or a generic nasal spray, sold without a prescription) into one nostril. If there is no response after 2 to 3 minutes, give another dose.
- If you are trained, give rescue breaths. Otherwise place the person on their side so they do not choke.
- Stay with them. Naloxone can wear off before meperidine does, so the overdose can return even after the person wakes up.
- Most states have Good Samaritan laws that protect people who call 911 for an overdose from some drug charges.
What is meperidine withdrawal like, and how long does it last?
People who take meperidine regularly for more than a few weeks become physically dependent, even when they take it exactly as prescribed. Dependence is not the same as addiction, but it means stopping suddenly causes withdrawal.
- 3 to 12 hoursEarly symptomsAnxiety, restlessness, yawning, sweating, runny nose, watery eyes, and muscle aches.
- Days 1 to 3Peak withdrawalDiarrhea, stomach cramps, nausea and vomiting, goosebumps, dilated pupils, fast heartbeat, and strong cravings. Rarely dangerous in healthy adults, but dehydration can be serious.
- Days 5 to 10, then weeksLingering symptomsPoor sleep, low mood, low energy, and cravings can continue for weeks. Tolerance falls quickly, which raises the risk of overdose if use restarts.
See the withdrawal timelines and the full meperidine withdrawal guide.
Is meperidine legal?
In the United States, meperidine is a Schedule II controlled substance. The only legal way to get it is with a prescription from a clinician registered with the Drug Enforcement Administration (DEA), filled by a licensed pharmacy. Depending on state law, that can be a physician, nurse practitioner, or physician assistant.
- Refills: Schedule II prescriptions cannot be refilled. A prescriber can issue several prescriptions at once, each dated with the earliest fill date, for up to a 90-day supply.
- Telehealth: federal flexibilities let DEA-registered clinicians prescribe Schedule II to V medicines after a telemedicine visit, without a prior in-person exam, through December 31, 2026. A permanent DEA rule was under final review in late 2026. State rules can be stricter.
- Monitoring: prescribers and pharmacists in most states check a prescription drug monitoring program, a database of controlled-substance prescriptions, before prescribing or dispensing.
Outside the United States
| Country | Status |
|---|---|
| United Kingdom | Class A (as pethidine) |
| Canada | Schedule I of the Controlled Drugs and Substances Act |
| Australia | Schedule 8 controlled drug |
| International | Schedule I of the 1961 Single Convention on Narcotic Drugs |
Frequently asked questions about meperidine
Is Demerol still used?
Rarely. Hospitals have mostly replaced it with safer opioids because of seizure risk and dangerous drug interactions.
Why is meperidine dangerous with antidepressants?
With MAO inhibitors it can cause a fatal reaction, and with SSRIs, SNRIs, and other serotonin drugs it can cause serotonin syndrome.
What is normeperidine?
A breakdown product that lasts much longer than meperidine and can cause tremors and seizures as it builds up.
Is pethidine the same as meperidine?
Yes. Pethidine is the international name; meperidine is the US name for the same drug.
Is meperidine used for shivering after surgery?
Small injected doses are sometimes used to stop shivering after anesthesia, an effect other opioids have less.
Sources
- Demerol (meperidine) prescription information, DailyMed, US National Library of Medicine.
- CDC Clinical Practice Guideline for Prescribing Opioids for Pain, 2022, Centers for Disease Control and Prevention, MMWR.
- FDA warns about serious risks and death when combining opioid pain or cough medicines with benzodiazepines, US Food and Drug Administration, 2016.
- Information about naloxone and nalmefene, US Food and Drug Administration.
- Controlled Substance Schedules, DEA Diversion Control Division.
- 21 CFR 1306.12, Refilling prescriptions; issuance of multiple prescriptions (Schedule II), Electronic Code of Federal Regulations.
- Prescribing controlled substances via telehealth, US Department of Health and Human Services.
- BeSafeRx: Your Source for Online Pharmacy Information, US Food and Drug Administration.
This guide summarizes the sourced DoseUses Meperidine profile, written from FDA labels, DEA rules, and federal health agencies. It is educational and is not medical advice. Last updated October 5, 2026.
