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Brand names

  • Astramorph
  • Astramorph PF
  • Doloral
  • Duramorph
  • Epimorph
  • Infumorph
  • Kadian
  • M-Elson
  • Morphine H.P
  • Morphine Sulfate
  • Morphitec
  • M.O.S.
  • M.O.S.-S.R.
  • MS Contin
  • MS-IR
  • OMS Concentrate
  • Opium Tincture
  • Oramorph SR
  • Paregoric
  • RMS Uniserts
  • Roxanol
  • Roxanol 100
  • Roxanol SR
  • Statex


To relieve severe pain.

How it works

Opioids such as morphine relieve pain by acting on specific areas of the brain and spinal cord that process pain signals from nerves throughout the body.

Side effects

Serious side effects are indistinguishable from those of overdose: Confusion; severe drowsiness, weakness, or dizziness; slurred speech; small, pinpoint pupils; cold, clammy skin; slow breathing; seizures; loss of consciousness.
Dizziness or lightheadedness, nausea or vomiting, constipation, drowsiness, itching.
Less common
Mood swings, false sense of well-being (euphoria), urinary retention, jerking body movements (myoclonus), hallucinations, sweating.

Possible interactions

Other medicaments:

    Morphine may increase the effects of:

  • antihypertensives and cause excessive lowering of blood pressure.
  • atropinelike medicaments and increase the risk of constipation and urinary retention.
  • metformin (Glucophage).
  • other medicaments with sedative effects.
  • Morphine may decrease the effects of:

  • metoclopramide (Reglan).
  • Morphine taken concurrently with:

  • benzodiazepines may result in increased risk of respiratory depression.
  • cimetidine (Tagamet) may result in morphine toxicity.
  • fluoxetine (Prozac) may antagonize morphine's pain-relieving effect.
  • hydroxyzine (Vistaril) can increase pain relief but carries the risk of increased respiratory depression.
  • medicines that increase CYP 3A4 will blunt morphine benefits and those that inhibit or use 3A4 for removal from the body may increase morphine blood levels. Caution and dosing adjustments are prudent.
  • metoclopramide (Reglan) may lead to increased morphine effects.
  • monoamine oxidase (MAO) type A inhibitors may cause the equivalent of an acute narcotic overdose: unconsciousness and severe depression of breathing, heart rate and circulation. A variation, can be excitability, convulsions, high fever and rapid heart action.
  • naltrexone (ReVia or Narcan) may lead to sudden withdrawal symptoms.
  • phenothiazines may cause excessive and prolonged depression of brain functions, breathing and circulation.
  • rifampin (Rifater, others) may lower morphine benefits.
  • ritonavir (Norvir) may lead to lower morphine benefits.
  • tramadol-{Ultram) may increase CNS side effects.
  • trovafloxacin (Trovan) may blunt trovafloxacin benefits.
  • zidovudine (AZT) may increase the toxicity of both medicaments; avoid concurrent use.
Herbal medicines or minerals:
Valerian and kava kava may interact additively (drowsiness). Avoid these combinations. St. John's wort can change (inducing or increasing) P450 3A4 enzymes, blunting the effects of morphine. Talk to your doctor before you combine any herbal medicines with morphine.
Opioid analgesics can intensify the intoxicating effects of alcohol and alcohol can intensify the depressant effects of opioids on brain function, breathing and circulation.
Tobacco smoking:
Increase in drowsiness and pain relief; impairment of mental and physical performance.
It is advisable to limit this medicament to short-term use. Longer-term use requires gradual tapering (decreasing) of doses to minimize possible effects of withdrawal: body aches, fever, sweating, nervousness, trembling, weakness, runny nose, sneezing, rapid heart rate, nausea, vomiting, stomach cramps, diarrhea.

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