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RMS Side Effects

Generic name: morphine

Medically reviewed by Last updated on Feb 9, 2024.

Note: This document contains side effect information about morphine. Some dosage forms listed on this page may not apply to the brand name RMS.

Applies to morphine: oral capsule extended release, oral capsule extended release 24 hr, oral solution, oral tablet, oral tablet extended release. Other dosage forms:


Oral route (Capsule, Extended Release; Solution; Tablet; Tablet, Extended Release)

Addiction, Abuse, and MisuseMorphine sulfate exposes users to risks of addiction, abuse, and misuse, which can lead to overdose and death. Assess each patient’s risk before prescribing, and monitor regularly for these behaviors and conditions.Opioid Analgesic Risk Evaluation and Mitigation Strategy (REMS)To ensure that the benefits of opioid analgesics outweigh the risks of addiction, abuse, and misuse, the Food and Drug Administration (FDA) has required a Risk Evaluation and Mitigation Strategy (REMS) for these products.Life-Threatening Respiratory DepressionSerious, life-threatening or fatal respiratory depression may occur. Monitor closely, especially upon initiation or following a dose increase. Instruct patients to swallow morphine sulfate whole to avoid exposure to a potentially fatal dose of morphine.Accidental IngestionAccidental ingestion of morphine sulfate, especially in children, can result in fatal overdose of morphine.Neonatal Opioid Withdrawal SyndromeProlonged use of morphine sulfate during pregnancy can result in neonatal opioid withdrawal syndrome, which may be life-threatening if not recognized and treated. If prolonged opioid use is required in a pregnant woman, advise the patient of the risk of neonatal opioid withdrawal syndrome and ensure that appropriate treatment will be available.Risks From Concomitant Use With Benzodiazepines or Other CNS DepressantsConcomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for use in patients for whom alternative treatment options are inadequate; limit dosages and durations to the minimum required; and follow patients for signs and symptoms of respiratory depression and sedation.

Serious side effects of RMS

Along with its needed effects, morphine (the active ingredient contained in RMS) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking morphine:

Less common

Incidence not known

Get emergency help immediately if any of the following symptoms of overdose occur while taking morphine:

Symptoms of overdose

Other side effects of RMS

Some side effects of morphine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

Incidence not known

For Healthcare Professionals

Applies to morphine: compounding powder, injectable solution, injectable tablet soluble, intramuscular solution, intravenous solution, oral capsule, oral capsule extended release, oral concentrate, oral liquid, oral solution, oral tablet, oral tablet extended release, rectal suppository, spinal solution.

Nervous system

Very common (10% or more): Drowsiness (28%)

Common (1% to 10%): Dizziness, sedation, fever, anxiety, confusion, tremor, diaphoresis, lethargy, feeling of warmth

Uncommon (0.1% to 1%): Withdrawal symptoms after either abrupt cessation or fast tapering of the drug, headache, chills, flu syndrome, malaise, withdrawal syndrome, pallor, facial flushing, syncope, loss of concentration, insomnia, amnesia, paresthesia, agitation, vertigo, foot drop, ataxia, hypesthesia, slurred speech, hallucinations, euphoria, apathy, seizures, myoclonus

Frequency not reported: Inflammatory masses including granulomas (some of which have resulted in serous neurologic impairment including paralysis) in patients receiving continuous infusion of opioids via indwelling intrathecal catheter[Ref]

Central nervous system side effects may be either depressant or excitatory. Excitatory symptoms are sometimes ignored as possible side effects of morphine. Severe adverse effects such as respiratory depression can be treated with the opioid antagonist naloxone.

Patients receiving continuous infusion of morphine sulfate via indwelling intrathecal catheter should be monitored for new neurologic signs or symptoms. Further assessment or intervention should be based on the clinical condition of the individual patient.

Myoclonic spasms may occur in patients receiving high dose morphine, particularly in the setting of renal dysfunction. Hyperalgesia has also been reported with high doses.[Ref]


Common (1% to 10%): Respiratory depression

Uncommon (0.1% to 1%): Hiccup, rhinitis, atelectasis, asthma, hypoxia, voice alteration, depressed cough reflex, noncardiogenic pulmonary edema, bronchospasm[Ref]


Common (1% to 10%): Dry mouth, constipation, nausea, diarrhea, anorexia, abdominal pain, vomiting

Uncommon (0.1% to 1%): Dysphagia, dyspepsia, stomach atony disorder, gastroesophageal reflux, delayed gastric emptying, biliary colic, increased gastroesophageal reflux, intestinal obstruction[Ref]

Morphine may cause constriction of the common bile duct and spasm of the sphincter of Oddi, thereby increasing intrabiliary pressure and worsening, rather than relieving, biliary colic.

In addition, morphine may cause intense but uncoordinated duodenal contraction and decreased gastric emptying.[Ref]


Common (1% to 10%): Chest pain

Uncommon (0.1% to 1%): Tachycardia, atrial fibrillation, hypertension, hypotension, palpitations, bradycardia, vasodilation[Ref]


Uncommon (0.1% to 1%): Abnormal thinking, abnormal dreams, depression, fearfulness, agitation, paranoia, psychosis, hypervigilance, hallucinations, delirium

Frequency not reported: Withdrawal symptoms after abrupt cessation of therapy[Ref]


Uncommon (0.1% to 1%): Urinary abnormality, urinary retention, urinary hesitancy[Ref]

The risk of acute urinary retention is very high when morphine is administered by epidural or intrathecal injection. Clinicians should be attentive to the increased risk of urosepsis in this setting, particularly if instrumentation of the urinary tract is necessary.[Ref]


Common (1% to 10%): Anemia, leukopenia

Uncommon (0.1% to 1%): Thrombocytopenia[Ref]


Uncommon (0.1% to 1%): Hyponatremia due to inappropriate ADH secretion, gynecomastia, amenorrhea, reduced libido, reduced potency, prolonged labor[Ref]


Common (1% to 10%): Asthenia, accidental injury

Uncommon (0.1% to 1%): Back pain, bone pain, arthralgia

Frequency not reported: Opioid-induced involuntary muscle hyperactivity with chronic high doses[Ref]


Common (1% to 10%): Rash

Uncommon (0.1% to 1%): Decubitus ulcer, pruritus, skin flush[Ref]


Uncommon (0.1% to 1%): Amblyopia, conjunctivitis, miosis, blurred vision, nystagmus, diplopia[Ref]


Very rare (less than 0.01%): Hypersensitivity reactions, anaphylaxis[Ref]


Uncommon (0.1% to 1%): Increases in hepatic enzymes[Ref]


Common (1% to 10%): Peripheral edema

Uncommon (0.1% to 1%): Hyponatremia

Frequently asked questions


1. Bellville JW, Forrest WH, Elashoff J, Laska E (1968) "Evaluating side effects of analgesics in a cooperative clinical study." Clin Pharmacol Ther, 9, p. 303-13

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3. Covington EC, Gonsalves-Ebrahim L, Currie KO, et al. (1989) "Severe respiratory depression from patient-controlled analgesia in renal failure." Psychosomatics, 30, p. 226-8

4. Littrell RA, Kennedy LD, Birmingham WE, Leak WD (1992) "Muscle spasms associated with intrathecal morphine therapy: treatment with midazolam." Clin Pharm, 11, p. 57-9

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7. Ogawa K, Iranami H, Yoshiyama T, Maeda H, Hatano Y (1993) "Severe respiratory depression after epidural morphine in a patient with myotonic dystrophy." Can J Anaesth, 40, p. 968-70

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9. Morley JS, Watt JWG, Wells JC, Miles JB, Finnegan MJ, Leng G (1993) "Methadone in pain uncontrolled by morphine." Lancet, 342, p. 1243

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20. Zsigmond EK, Vieira ZEG, Duarte B, Renigers SA, Hirota K (1993) "Double-blind placebo-controlled ultrasonographic confirmation of constriction of the common bile duct by morphine." Int J Clin Pharmacol Ther Toxicol, 31, p. 506-9

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.