Morphine
Morphine is a potent opioid analgesic used for severe pain, especially cancer pain and end-of-life care. Gold standard for comparison of other opioids.
About Morphine
Morphine is a full mu-opioid receptor agonist (phenanthrene opioid) (generic name: Morphine Sulfate) also sold under brand names including MS Contin, Kadian, and Roxanol. It is primarily used for Moderate to severe pain management, Cancer pain, Postoperative pain, and Chronic pain in opioid-tolerant patients (extended-release), among other conditions. Morphine is available in immediate-release oral tablet (15 mg, 30 mg), immediate-release oral solution (10 mg/5 ml, 20 mg/5 ml, 100 mg/5 ml concentrate), extended-release oral tablet (15 mg, 30 mg, 60 mg, 100 mg, 200 mg — ms contin), extended-release oral capsule (10–200 mg — kadian), iv/im/sc injection (1, 2, 4, 5, 8, 10, 15, 25, 50 mg/ml), and rectal suppository (5 mg, 10 mg, 20 mg, 30 mg) form. Healthcare providers commonly prescribe Morphine for conditions including Chronic Low Back Pain and Post-Herpetic Neuralgia (PHN).
Morphine at a Glance
- Generic name
- Morphine Sulfate
- Brand names
- MS Contin, Kadian, Roxanol
- Drug class
- Full Mu-Opioid Receptor Agonist (Phenanthrene Opioid)
- DEA schedule
- Schedule Schedule II (controlled substance)
- Pregnancy category
- FDA Category C — Animal studies have shown fetal harm at high doses. Prolonged use during pregnancy can cause neonatal opioid withdrawal syndrome (NOWS), which may be life-threatening if not recognized and treated. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus, and coordinate care with obstetric and neonatal teams.
- Available forms
- Immediate-release oral tablet (15 mg, 30 mg), Immediate-release oral solution (10 mg/5 mL, 20 mg/5 mL, 100 mg/5 mL concentrate), Extended-release oral tablet (15 mg, 30 mg, 60 mg, 100 mg, 200 mg — MS Contin), Extended-release oral capsule (10–200 mg — Kadian), IV/IM/SC injection (1, 2, 4, 5, 8, 10, 15, 25, 50 mg/mL), Rectal suppository (5 mg, 10 mg, 20 mg, 30 mg)
- Therapeutic categories
- Pain Management, Opioids, Controlled Substances, Palliative Care
- Conditions treated
- 2 related conditions on this site
What Morphine Is Used For
- Moderate to severe pain management
- Cancer pain
- Postoperative pain
- Chronic pain in opioid-tolerant patients (extended-release)
- End-of-life care and palliative medicine
- Dyspnea in terminal illness
Dosage Quick Reference
These are general dosage guidelines for Morphine. Your doctor will determine the appropriate dose for your specific situation.
| Condition | Starting Dose | Maintenance Dose |
|---|---|---|
| Acute moderate-to-severe pain (opioid-naive adult, oral IR) | 15–30 mg orally every 4 hours as needed | Titrate to effect; reassess within 24–72 hours |
| Acute pain (parenteral, opioid-naive adult) | 2–10 mg IV/IM/SC every 3–4 hours | Titrate; convert to oral when tolerated |
| Chronic pain (opioid-tolerant, extended-release) | 15 mg orally every 8–12 hours | Titrate by 25–50% no more often than every 1–2 days |
| Cancer pain (around-the-clock) | Calculate based on prior 24-hour opioid use | Add immediate-release morphine for breakthrough at 10–15% of total daily dose |
| Hepatic or severe renal impairment | Reduce starting dose by 50% | Extend dosing interval; monitor for accumulation |
Side Effects
Common Side Effects:
- Constipation (very common, often requires preventive treatment)
- Nausea and vomiting
- Drowsiness
- Dizziness
- Itching
- Dry mouth
- Sweating
Serious Side Effects (seek immediate medical attention):
- Respiratory depression (slow, shallow, or stopped breathing)
- Severe hypotension
- Signs of overdose (extreme drowsiness, pinpoint pupils, blue lips)
- Severe allergic reactions
- Serotonin syndrome (with serotonergic drugs)
- Adrenal insufficiency symptoms (long-term use)
See also: Drug Interactions ↓
Drug Interactions
Morphine has multiple high-risk interactions. Many are subject to FDA boxed warnings and require careful prescribing.
- Benzodiazepines and other CNS depressants (e.g., alprazolam, zolpidem, gabapentin, alcohol): Concurrent use causes additive respiratory depression, profound sedation, coma, and death. Reserve combination only when alternatives are inadequate; use the lowest effective doses for the shortest duration with close monitoring.
- Serotonergic agents (e.g., SSRIs, SNRIs, MAOIs, tramadol, ondansetron): Risk of serotonin syndrome (agitation, hyperthermia, clonus, autonomic instability). Monitor closely on initiation and dose changes.
- Mixed opioid agonist-antagonists or partial agonists (e.g., buprenorphine, nalbuphine, butorphanol): May reduce morphine analgesia and precipitate withdrawal in physically dependent patients. Avoid concurrent use.
- MAO inhibitors (e.g., phenelzine, selegiline): Risk of severe hypotension, hypertensive crisis, or serotonin syndrome. Avoid morphine within 14 days of MAOI use.
- Diuretics: Morphine may reduce the efficacy of diuretics through release of antidiuretic hormone, particularly in patients with congestive heart failure.
- Anticholinergic medications (e.g., diphenhydramine, oxybutynin, tricyclic antidepressants): Additive risk of severe constipation, urinary retention, and paralytic ileus.
Key Considerations
Controlled substance
Morphine is a Schedule Schedule II controlled substance under federal law. Prescriptions are regulated, refills may be restricted, and the medication has recognized potential for misuse or dependence. Use exactly as prescribed.
Known drug interactions
Morphine has documented interactions with other medications, supplements, and certain foods. Review the Drug Interactions section below and tell your healthcare provider about every medication you take, including over-the-counter products. Jump to section →
Multiple forms available
Morphine comes in more than one form (Immediate-release oral tablet (15 mg, 30 mg), Immediate-release oral solution (10 mg/5 mL, 20 mg/5 mL, 100 mg/5 mL concentrate), Extended-release oral tablet (15 mg, 30 mg, 60 mg, 100 mg, 200 mg — MS Contin), Extended-release oral capsule (10–200 mg — Kadian), IV/IM/SC injection (1, 2, 4, 5, 8, 10, 15, 25, 50 mg/mL), Rectal suppository (5 mg, 10 mg, 20 mg, 30 mg)). The right form for you depends on your condition, ease of use, and your provider's recommendation.
Additional Information
Morphine is the prototypical opioid analgesic and remains the standard against which all other opioids are compared. As a naturally occurring alkaloid derived from the opium poppy, it has been used for pain relief for centuries. Today, morphine is essential for treating moderate to severe pain, particularly in cancer, postoperative settings, and end-of-life care, though its use requires careful consideration of risks including addiction, abuse, and overdose.
Mechanism of Action
Morphine is a full agonist at mu-opioid receptors, with additional activity at kappa and delta receptors. Binding to mu receptors in the central nervous system produces analgesia, euphoria, respiratory depression, and physical dependence. Morphine also activates the descending inhibitory pain pathway and alters the perception of and emotional response to pain in higher brain centers.
Peripheral effects include decreased gastrointestinal motility (causing constipation), histamine release (causing itching and hypotension), and suppression of the cough reflex. The combination of central and peripheral effects accounts for both the therapeutic benefits and side effect profile of morphine.
Available Formulations
Morphine is available in numerous formulations to address different clinical needs. Immediate-release formulations include oral tablets and solution, suppositories, and injectable solutions for IV, IM, subcutaneous, epidural, and intrathecal administration. Extended-release formulations (MS Contin, Kadian, MorphaBond) are available for chronic pain requiring around-the-clock therapy. Concentrated oral solutions are available for patients with difficulty swallowing.
FDA-Approved Indications
Morphine is FDA-approved for the management of pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. Extended-release formulations are indicated only for patients who are opioid-tolerant and require around-the-clock pain control for an extended period. Morphine is also used for dyspnea management in end-of-life care and has been used historically as a treatment for pulmonary edema.
Dosing Guidelines
Morphine dosing must be individualized based on pain severity, prior opioid exposure, patient-specific factors, and response. For opioid-naive patients with severe acute pain, initial IV doses of 2-4 mg every 3-4 hours or oral doses of 10-15 mg every 4 hours may be appropriate. Doses should be titrated to effect. For extended-release formulations, patients must be opioid-tolerant (typically defined as receiving at least 60 mg oral morphine equivalents daily for at least one week).
Opioid Conversion Considerations
When converting between opioids or formulations, use established equianalgesic tables but apply conservative dose reductions (25-50%) due to incomplete cross-tolerance. Morphine oral bioavailability is approximately 30%, so parenteral doses are significantly lower than equivalent oral doses. Always monitor closely after any conversion.
Important Safety Considerations
Morphine carries boxed warnings for addiction, abuse, and misuse; life-threatening respiratory depression; neonatal opioid withdrawal syndrome; and interaction with benzodiazepines or other CNS depressants causing profound sedation, respiratory depression, coma, and death. Extended-release formulations carry additional warnings about risks from crushing or chewing tablets. Naloxone should be available when using morphine, and patients/caregivers should be educated about overdose recognition and response.
Drug Interactions
Concurrent use with benzodiazepines, other CNS depressants, or alcohol significantly increases the risk of respiratory depression and death; reserve concomitant use for patients without alternatives. CYP3A4 inhibitors may increase morphine effects; CYP3A4 inducers may decrease effects. MAO inhibitors can cause serotonin syndrome or opioid toxicity. Anticholinergic drugs may increase constipation and urinary retention risk.
Where Morphine Sits in a Pain Plan
Morphine's clearest place is severe pain with an identifiable cause and a defined course: cancer pain, pain after major surgery, and the pain and breathlessness of the last weeks of life, where it is among the most useful drugs in medicine and where withholding it causes real harm. Its place in long-standing pain without such a cause is much narrower. For chronic low back pain, exercise therapy, physical therapy, and non-opioid analgesia come first, and long-term opioid treatment produces small average gains in pain scores against substantial risk. For neuropathic pain, including post-herpetic neuralgia (PHN), agents such as gabapentin, pregabalin, and duloxetine are tried first, often with a topical treatment added, before an opioid is considered at all. Where morphine is used for persistent non-cancer pain, it works best as one part of a plan with stated functional goals, meaning something the patient should be able to do that they cannot do now, and with a review date at which continuing is an explicit decision rather than a default renewal.
Constipation, Naloxone and Recognizing Trouble Early
Two things are arranged at the same time as the first prescription. The first is a bowel plan. Opioid-induced constipation does not fade with time the way nausea and drowsiness usually do, so a stimulant laxative, with polyethylene glycol added as needed, is started alongside the opioid rather than after the problem appears. Bulk fiber alone is not sufficient and can make matters worse when transit is already slowed. The second is naloxone, prescribed to the household rather than only to the patient, with whoever lives there shown how to use it, since an overdose is witnessed far more often than it is self-treated.
Opioid use disorder is a risk of treatment, not something morphine treats. It is more likely at higher doses, with longer duration, with a personal or family history of substance use, and alongside untreated depression or anxiety, and it is worth naming openly at the outset so that a patient who develops it feels able to say so. The signs are behavioral rather than pharmacological: running out early, escalating the dose without discussion, taking it for distress rather than for pain, obtaining it from more than one prescriber, or continuing despite clear harm. Physical dependence and tolerance are expected with continued use and are not the same thing as addiction. If opioid use disorder does develop, the treatment for it is specific and effective, meaning buprenorphine or methadone started without a gap that leaves the patient in withdrawal, and our psychiatric colleagues arrange that alongside a continuing plan for the original pain, which does not disappear because the medication changed. The MedlinePlus morphine monograph covers safe storage and disposal, the NIDA overview of prescription opioids explains how dependence and addiction differ, and our article on managing chronic pain without opioids sets out the alternatives that come first.
Special Populations
Dose reduction is required in hepatic impairment (active metabolites may accumulate) and renal impairment (accumulation of morphine-6-glucuronide can cause toxicity). Elderly patients require lower initial doses and careful titration due to altered pharmacokinetics and increased sensitivity. Use during pregnancy, particularly near delivery, can cause neonatal opioid withdrawal syndrome. Morphine passes into breast milk; benefits and risks should be considered.
Learn more at MedlinePlus
Frequently Asked Questions
Questions About Morphine?
Your primary care doctor in St. Petersburg can review Morphine alongside everything else you take, check for interactions, and adjust your plan as your health changes.
Request an appointmentMedical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.