What is Morphine and How Does it Work?

Morphine is a centrally acting opioid analgesic that binds to opiate receptors in the central nervous system and blocks ascending pain pathways. This results in reducing a patient’s perception of pain without altering the cause of the pain. Morphine also causes respiratory depression, peripheral vessel dilation, inhibition of intestinal peristalsis, sphincter of body spasm, and stimulation of chemoreceptors that cause vomiting.

Uses of Morphine

Morphine is available as both immediate and sustained-release tablets, oral solution, and injection. The immediate-release tablets and morphine injection are used to treat severe pain, while sustained-release tablets are used to treat severe and persistent pain, particularly cancer pain.

Dosage and Administration

The usual dose of morphine for adults is 10 to 30 milligrams every four hours as needed. For sustained-release tablets, the recommended dose for adults is 30 to 100 milligrams every 8 to 12 hours. When using it as a subcutaneous or intramuscular injection, the dosage for adults is 5 to 20 milligrams per 70 kilograms every four hours, and when using it as an intravenous injection, the dosage is 2.5 to 15 milligrams per 70 kilograms in four to five milliliters water for injection over five minutes. For children, the recommended dosage is 0.1 to 0.2 milligrams per kilogram every four hours, and the maximum dose is 15 milligrams.

Side Effects and Precautions

Morphine should not be administered to patients with severe respiratory impairment or decompensated hepatic impairment. It should not be initiated in elderly patients or those with renal or hepatic impairment. Patients with respiratory impairment, head injury, raised intracranial pressure, uncontrolled epilepsy, or urathroprostatic disorders should receive morphine with caution. It should not be combined with opioid analgesics with mixed agonist-antagonist activity, and it should not be combined with alcohol and drugs acting on the central nervous system.

Common adverse effects of morphine include dose-related sedation and respiratory depression, nausea, vomiting, constipation, urinary retention, confusion, raised intracranial pressure, and pruritus. In the event of an overdose, excessive sedation, respiratory depression, and coma may occur, and management of respiratory depression includes assisted ventilation and/or administration of dalekson. Patients should be monitored closely for several hours.


Morphine is a powerful analgesic that is useful for treating severe and persistent pain. However, it comes with significant side effects, and its administration requires careful consideration of the patient’s age, hepatic and renal function, and other underlying medical conditions. Patients receiving morphine must be closely monitored for adverse effects and potential drug interactions. If you are experiencing pain, always consult with a healthcare provider to determine the most appropriate treatment option.