Morphine Side Effects

Morphine Side Effects

Morphine is an opioid drug. It gives a strong analgesic effect by increasing the pain threshold. Morphine reduces the excitability of the cough center, thereby making cough to become scarcer or to stop completely. It inhibits the breathing and vomiting center. Morphine affects the gastrointestinal tract, bronchi, cardiovascular system, and the urinary tract.


  • In medical practice, the drug is used as an analgesic for strong pain syndrome (including for myocardial infarction, before surgery, and in the postoperative period, and in malignant growth).
  • As an antitussive drug, for example, in major surgery, and trauma of the chest.
  • Severe shortness of breath caused by acute cardiovascular failure, and pulmonary edema.

Side effects

  • nausea and vomiting;
  • itchy skin;
  • constipation;
  • spasm of the ureters and urethral sphincter, and as a result pain and difficulty with urination, frequent urination, impaired urine flow;
  • dyskinesia (abnormality in motor function) of the gall bladder and bile ducts.

Rare side effects

Cardiovascular system disorders: slow heartbeat and low blood pressure. There may also be palpitations and high blood pressure, cardiac arrhythmias, syncope.

Digestive system disorders: reduced salivation and as a result, dry mouth, increased risk of dental caries, periodontal diseases, lesions of the oral mucosa by fungi of the genus Candida, poor appetite, abdominal pain, weakening of the function of the bowel (atony), bowel obstruction, expansion and impairment of the large intestine (toxic megacolon), which manifests in the form of constipation, bloating, nausea, stomach cramps, and vomiting.

Disorders of the central and peripheral nervous system: calming effect and drowsiness, false sense of well-being, impaired ability to concentrate, decreased mental abilities, apathy, and decreased motor activity. The drug may cause an exciting effect in elderly patients and children. There may be anxiety, irritability, mental disorder with impaired consciousness and hallucinations. There may also be an elevated risk of intracranial pressure with the risk of cerebral blood flow disorder, dizziness, headache, nervous exhaustion, insomnia and nightmares, sensation of pins and needles, numbness, and tingling, involuntary muscle twitching, seizures, loss of coordination, blurred vision, involuntary rhythmic movements of the eyeball, double vision, pupillary constriction, ringing in the ears, and change in taste.

Respiratory system disorders: reduced rate and depth of breathing and breathing rate, to the extent of complete cessation, bronchospasm, and drop in the lung. Morphine is known for its antitussive effect that in some cases may be undesirable.

Reproductive system disorders: loss of sexual desire and/or potency. Prolonged use of morphine in men decreases the secretion of testosterone (sex hormone) and secondary sexual characteristics are subjected to regression. In women, ovulation is disturbed and menstruation can disappear. Morphine reduces the amount of breast milk.

Allergic reactions: wheezing, flushing, swelling of the face and the trachea, spasm of the muscles of the larynx (angioedema), chills. Itching often around the nose, rash, and urticaria.

Other reactions: increased sweating, change in voice, weight loss, dehydration, pain in the arms and legs. Deterioration of thyroid function. Local reactions: redness, swelling, and burning at the site where the drug was administered.

The most dangerous side effect of morphine is its depressing effect on the vital centers of the medulla oblongata. As a result, breath is slowed down to the extent of complete cessation, slow heartbeat, low blood pressure, and possible death. The extent of these life-threatening effects is proportional to the dose of the drug.

Drug dependence

Dependence (mental and physical) may develop after 2 to 3 weeks of regular use.

Withdrawal syndrome

Withdrawal syndrome develops after a relatively short period of regular use (about one week). Occurs 8 to 16 hours after the last dose of morphine and manifests as irritability, aggression, and insomnia. There may be yawning, trembling, body aches, nausea and vomiting, watery eyes, runny nose, sweating, and dilated pupils. There may also be diarrhea and abdominal pain. Blood pressure increases, heartbeat becomes frequent, and body temperature increases. The duration of acute withdrawal syndrome is 5 to 14 days.


Decreased sensitivity to the drug and reduced analgesic effect develop very quickly, while a steady increase in dose can lead to overdose and death from respiratory standstill.

Side effects during pregnancy and breast-feeding

Morphine has been assigned to pregnancy category C by the FDA (meaning that the drug affects the fetus adversely). During pregnancy and lactation, morphine should be used only for emergency cases because the drug crosses the placenta, gets into the breast milk, and may cause respiratory depression and lead to drug dependence in the fetus and newborn. It has a damaging effect on the fetus. The drug is not used for pain relief in labor for it can increase the duration of labor. Newborns whose mothers misused morphine suffer from withdrawal syndromes.

Side effects in children

Children under 2 years of age are more susceptible to the effects of opioid analgesics such as morphine. They may develop paradoxical reactions – excitement, anxiety. Elongation of the speed of conversion of the drug in newborns may strengthen such side effects of morphine as respiratory depression, and, rarely, seizures. Also, such side effects of opioids as nausea, paralytic ileus, pruritus and urinary retention are observed quite often.

To reduce the degree of side effects, doses should be strictly selected on an individual basis.

Changes in laboratory parameters

By causing biliary tract spasm, morphine disrupts outflow from the pancreas, which leads to higher content of amylase and lipase in the blood. Morphine may alter blood levels of such enzymes as lactate dehydrogenase (LDH), leucine aminopeptidase (LAP), and transaminase. There may be intensified excretion of adrenal epinephrine and decreased excretion of 17-ketosteroids. There may be increase in the blood sugar levels. Affecting the pituitary gland, morphine induces an increase in the secretion of pituitary hormones, especially antidiuretic hormone. However, adrenocorticotropic hormone secretion may reduce. With prolonged use of morphine in men, testosterone blood levels (sex hormone) decreases. Morphine inhibits secretion of thyroid hormones – blood tests show decreased concentration of T3 and T4.

  • Severe abdominal pain whose cause is not clear.
  • Children under 2 years of age and pregnant women.
  • Brain injury.
  • Increased intracranial pressure
  • Status epilepticus.
  • Mental disorder with impaired consciousness.
  • Acute alcohol intoxication.
  • Severe nervous system depression.
  • Respiratory impairment due to suppression of the respiratory center.
  • Severe hepatic impairment.
  • Simultaneous use of some antidepressants and other MAO inhibitors.
  • Individual intolerance.
  • Pulmonary heart disease in patients with chronic lung diseases.
  • Paralytic ileus

Restrictions to use

  • general extreme exhaustion
  • bronchial asthma
  • chronic obstructive bronchitis
  • cardiac arrhythmias
  • convulsions
  • drug dependence, alcoholism
  • suicidal tendencies
  • emotional instability
  • surgery on the gastrointestinal tract and on the urinary system
  • lowering of thyroid function
  • severe inflammatory bowel diseases
  • enlargement of the prostate
  • narrowing of the urethra
  • kidney and/or liver failure, adrenal cortex insufficiency
  • old age (metabolism and excretion of morphine slow down, the level of morphine in the blood increases).


When using morphine, you should not drive or engage in activities that require quick reaction.

In order to eliminate side effects such as nausea and vomiting, abnormalities in urine and biliary excretion when taking morphine, additional corrective drugs (laxatives, antiemetics, antispasmodic) are prescribed.

You need to be especially careful when using morphine in the home.

A careful narcotic dose balance is not possible, the risk of overdose increases.

Morphine and alcohol

Alcohol consumption is not allowed when using morphine. Simultaneous use of other drugs acting on the central nervous system (antihistamines, sedatives, psychotropics and other pain medications) is possible only with the permission and under the supervision of a doctor.