Morphine Side Effects

Medically reviewed by Drugs.com. Last updated on Oct 1, 2024.

Applies to morphine: injection solution.

Other dosage forms:

• oral capsule extended release, oral capsule extended release 24 hr, oral solution, oral tablet, oral tablet extended release

Serious side effects of morphine

Along with its needed effects, morphine 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 or nurse immediately if any of the following side effects occur while taking morphine:

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

Symptoms of overdose

• bluish lips or skin
• dizziness
• fainting
• irregular heartbeat
• lightheadedness
• low blood pressure or pulse
• slow heartbeat
• unconsciousness

Other side effects of morphine

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:

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 adverse events

• 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]

Respiratory

• 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]

Gastrointestinal

• 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]

Cardiovascular

• Common (1% to 10%): Chest pain
• Uncommon (0.1% to 1%): Tachycardia, atrial fibrillation, hypertension, hypotension, palpitations, bradycardia, vasodilation^[Ref]

Psychiatric

• 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]

Genitourinary

• 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]

Hematologic

• Common (1% to 10%): Anemia, leukopenia
• Uncommon (0.1% to 1%): Thrombocytopenia^[Ref]

Endocrine

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

Musculoskeletal

• 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]

Dermatologic

• Common (1% to 10%): Rash
• Uncommon (0.1% to 1%): Decubitus ulcer, pruritus, skin flush^[Ref]

Ocular

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

Hypersensitivity

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

Hepatic

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

Metabolic

• Common (1% to 10%): Peripheral edema
• Uncommon (0.1% to 1%): Hyponatremia

Frequently asked questions

• Which drugs cause opioid-induced constipation?
• Which painkiller should you use?
• How does fentanyl compare to heroin or other opiates?

Further information

Morphine side effects can vary depending on the individual. 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.

Medical Disclaimer