meperidine vs morphine
Side-by-side comparison of meperidine and morphine Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Demerol
MS Contin, Kadian
Meperidine is a strong pain medicine. It is used to treat severe, acute pain when other pain medicines are not strong enough.
Morphine is a strong pain medicine. It is used to treat severe pain that needs an opioid medicine when other treatments don't work well enough.
Meperidine is used to manage acute pain that is severe enough to need an opioid pain medicine. It is for use when other treatments do not work well enough. Meperidine should not be used for chronic, long-lasting pain. Taking meperidine for a long time may increase the risk of seizures.
Morphine is used to manage severe pain in adults and children who weigh at least 110 pounds. It is for pain that requires an opioid medicine. It is used when other pain treatments are not strong enough or cannot be tolerated.
Meperidine is an opioid agonist. It works by binding to receptors in the brain and spinal cord. This reduces the feeling of pain.
Morphine works by attaching to receptors in the brain and spinal cord. These receptors are involved in sending pain signals. By binding to these receptors, morphine blocks pain signals and reduces pain.
- • Lightheadedness
- • Dizziness
- • Sleepiness
- • Nausea
- • Vomiting
- • Constipation
- • Nausea
- • Feeling sleepy
- • Lightheadedness
- • Dizziness
- Allergic reaction to the drug 3,248
- Drug not working 1,271
- Pain 1,250
- Feeling sick to your stomach 1,133
- Using the drug for a condition it is not approved for 861
- Pain 5,857
- Feeling sick to your stomach 5,534
- Medicine not working 5,006
- Throwing up 4,333
- Death 4,305
Meperidine has a boxed warning. This means it has serious risks. These risks include: Medication errors that can cause overdose, addiction, abuse, and misuse, life-threatening respiratory depression, accidental ingestion (especially by children) can cause a fatal overdose, dangerous effects when taken with benzodiazepines or other CNS depressants, and neonatal opioid withdrawal syndrome. Make sure you read the Medication Guide.
Morphine can cause addiction, abuse, and misuse, which can lead to overdose and death. It can also cause life-threatening breathing problems, especially when you start taking it or after a dose increase. Accidental ingestion, especially by children, can cause a fatal overdose. Taking morphine with benzodiazepines or other CNS depressants (including alcohol) can cause severe sedation, breathing problems, coma, and death. If you use morphine for a long time during pregnancy, your baby could have withdrawal symptoms after birth.
Taking meperidine for a long time during pregnancy can cause withdrawal symptoms in the newborn. Meperidine is not recommended during or right before labor because it can cause breathing problems in the baby.
Morphine may harm your unborn baby. Using morphine for a long time during pregnancy can cause withdrawal symptoms in the newborn. Tell your doctor if you are pregnant or plan to become pregnant.
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How to Read This meperidine vs morphine Comparison
meperidine is classified in the Opioid Analgesic drug class, while morphine sits within the Opioid Analgesic class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, meperidine has 7,763 submissions while morphine has 25,035. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between meperidine and morphine — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.