Morphine

Generic Name: Morphine Sulfate

Brand Names: MS Contin, Kadian, Roxanol

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.

Pain ManagementOpioidsControlled SubstancesPalliative Care

Drug Class

Full Mu-Opioid Receptor Agonist (Phenanthrene Opioid)

DEA Schedule

Schedule Schedule II

Pregnancy

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)

What It's 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. 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)

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.

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.

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

All full opioid agonists carry a meaningful risk of physical dependence and addiction with prolonged use. Morphine's addiction risk is comparable to other potent opioids such as oxycodone and hydromorphone. Risk is highest with daily long-term use, higher doses, personal or family history of substance use disorder, and concurrent untreated mental health conditions.

Immediate-release morphine takes effect within 30 to 60 minutes and lasts 3 to 4 hours, making it suitable for acute pain or breakthrough pain. Extended-release formulations release medication gradually over 8 to 12 hours and are intended only for opioid-tolerant patients with chronic, around-the-clock pain. Crushing, chewing, or breaking extended-release tablets can release the entire dose at once, causing fatal overdose.

Constipation is nearly universal with morphine because opioids slow gut motility. Begin a stimulant laxative such as senna at the same time you start morphine, drink plenty of fluids, and stay as physically active as your condition allows. If constipation persists despite these measures, your provider may prescribe a peripherally acting mu-opioid receptor antagonist (such as methylnaltrexone or naloxegol).

If you remember within a few hours, take the missed dose as soon as possible and resume your normal schedule. If it is close to the time of your next dose, skip the missed one — never double up. For breakthrough pain in the meantime, use only the immediate-release morphine prescribed for that purpose.

Anyone prescribed morphine — particularly at higher doses, alongside benzodiazepines, or with a history of substance use disorder, sleep apnea, or respiratory disease — should have naloxone available at home. Family members should be trained to recognize overdose (extreme drowsiness, slow or absent breathing, blue lips) and to administer naloxone while waiting for emergency services.

Yes. Tolerance to the analgesic and respiratory depressant effects develops over weeks to months of regular use, often requiring dose increases to maintain pain relief. Tolerance to constipation, however, is minimal — this side effect persists indefinitely. Your prescriber will balance dose escalation against side effects and overall function.

Related Health Conditions

This medication is commonly used to treat or manage the following conditions:

Attention Deficit Hyperactivity Disorder (ADHD)

ADHD is a neurodevelopmental disorder marked by inattention, hyperactivity, and/or impulsivity, stemming from complex interactions between genetics, brain differences, and environmental factors, not poor parenting.

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Medical 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.