Morphine
Potent opioid analgesic for severe pain management
Quick Facts About Morphine
Key Takeaways About Morphine
- Powerful pain relief: Morphine is one of the most effective analgesics available, primarily used for severe and cancer-related pain
- Risk of dependence: Repeated use can lead to tolerance, physical dependence, and addiction – always follow your prescriber’s instructions exactly
- Never combine with alcohol: Mixing morphine with alcohol or other CNS depressants can cause fatal respiratory depression
- Do not stop abruptly: Stopping morphine suddenly can cause serious withdrawal symptoms – always taper under medical supervision
- Keep out of reach of children: Accidental ingestion by a child can be fatal – store securely and dispose of unused medication properly
What Is Morphine and What Is It Used For?
Morphine is a potent opioid analgesic derived from the opium poppy. It is used to treat severe pain that does not respond to other painkillers, particularly cancer pain, acute post-operative pain, and pain in palliative and end-of-life care. It works by binding to opioid receptors in the brain and spinal cord.
Morphine belongs to the class of medicines known as opioid analgesics (sometimes called narcotic painkillers). It has been used in medicine for over two centuries and remains one of the most important drugs on the WHO Model List of Essential Medicines. Morphine is the gold standard against which the potency of all other opioid medications is measured.
The active substance in morphine preparations is morphine hydrochloride, which has a powerful pain-relieving (analgesic) effect. Morphine works by binding primarily to mu-opioid receptors in the central nervous system. This action blocks the transmission of pain signals from the body to the brain and alters the emotional perception of pain, providing significant relief even from the most severe pain.
Morphine is prescribed for a range of severe pain conditions, including:
- Cancer pain: One of the most common indications, particularly for moderate-to-severe cancer-related pain following the WHO analgesic ladder
- Acute severe pain: Post-surgical pain, trauma-related pain, and pain from myocardial infarction
- Palliative care: End-of-life pain management and relief of breathlessness in terminal illness
- Chronic non-cancer pain: In select cases when other treatments have failed, under strict medical supervision
Morphine is available in various formulations to suit different clinical needs. Immediate-release oral solutions provide rapid onset of action (within 20–30 minutes), while modified-release tablets offer sustained pain relief over 12–24 hours. Injectable forms are used in hospitals for acute pain or when oral administration is not possible.
The World Health Organization recommends a stepwise approach to pain management. Morphine sits at Step 3 (strong opioids) for severe pain, used when Step 1 (non-opioids like paracetamol) and Step 2 (weak opioids like codeine or tramadol) provide insufficient relief. This approach ensures that the least potent effective treatment is used first.
What Should You Know Before Taking Morphine?
Before taking morphine, inform your doctor about all medical conditions, especially respiratory problems, liver or kidney disease, history of substance abuse, and current medications. Morphine must not be used if you have severe respiratory depression, acute airway obstruction, or acute alcohol intoxication. It carries significant risks of dependence and addiction.
Contraindications
You must not use morphine if you have any of the following conditions:
- Severe respiratory depression – significantly impaired breathing capacity
- Excessive airway secretions – large amounts of mucus in the airways
- Acute liver disease – severe hepatic impairment
- Acute states of agitation during alcohol or sedative intoxication
- Allergy to morphine hydrochloride or any other ingredient in the medication
- Paralytic ileus – bowel obstruction or severely reduced gut motility
Never stop taking morphine suddenly without consulting your doctor. Abrupt discontinuation after prolonged use can cause severe withdrawal symptoms including body aches, tremors, diarrhea, nausea, anxiety, irritability, rapid heartbeat, and dilated pupils. Your doctor will gradually reduce your dose over time.
Warnings and Precautions
Talk to your doctor or pharmacist before using morphine if you have any of the following conditions, as special care and dose adjustments may be needed:
- Asthma or chronic obstructive pulmonary disease (COPD) – morphine can worsen breathing difficulties
- Head injury or raised intracranial pressure – morphine can obscure neurological signs
- Reduced kidney or liver function – affects how your body processes the drug
- Low blood pressure (hypotension) due to reduced blood volume
- Underactive thyroid (hypothyroidism) – increased sensitivity to opioids
- Pancreatitis or inflammatory bowel disease
- Constipation or biliary/urinary tract spasms
- Prostatic hypertrophy – may worsen urinary retention
- Adrenal insufficiency – morphine can suppress adrenal function
- Sleep apnea – morphine increases the risk of sleep-related breathing disorders
Tolerance, Dependence, and Addiction
Morphine carries a significant risk of tolerance, physical dependence, and addiction (substance use disorder), which can lead to life-threatening overdose. Understanding these risks is essential for safe use:
Tolerance means that over time, higher doses may be needed to achieve the same level of pain relief. Physical dependence means the body adapts to the drug, and withdrawal symptoms occur when it is stopped suddenly. Addiction (substance use disorder) involves compulsive drug-seeking behavior despite harmful consequences.
You may be at higher risk of developing dependence or addiction if:
- You or a family member has a history of alcohol, prescription drug, or illegal drug misuse
- You are a current smoker
- You have a history of depression, anxiety, or other mental health conditions
- You have previously been treated for substance use disorder
Warning signs that may indicate developing dependence include needing the medicine for longer than prescribed, needing higher doses than recommended, using it for reasons other than pain (e.g., to feel calm or sleep), and feeling unwell when you stop taking it.
Morphine can cause sleep apnea (pauses in breathing during sleep) and sleep-related hypoxemia (low blood oxygen). Symptoms include breathing pauses during sleep, waking at night due to shortness of breath, difficulty staying asleep, and excessive daytime drowsiness. Contact your doctor if you or anyone around you notices these symptoms.
Pregnancy and Breastfeeding
If you are pregnant, breastfeeding, think you may be pregnant, or are planning to have a baby, ask your doctor or pharmacist for advice before using morphine.
Pregnancy: Morphine should only be used during pregnancy when clearly necessary and under strict medical supervision, as there is a risk of harm to the fetus. Prolonged use of morphine during pregnancy can cause neonatal opioid withdrawal syndrome (neonatal abstinence syndrome) in the newborn, which requires specialized medical treatment. Symptoms in the newborn may include excessive crying, tremors, feeding difficulties, and seizures.
Breastfeeding: Morphine passes into breast milk. Breastfeeding is generally not recommended during morphine therapy due to the risk of sedation and respiratory depression in the nursing infant. Always consult your doctor before using morphine while breastfeeding.
Driving and Operating Machinery
Morphine can impair your ability to react quickly and make decisions. This effect should be considered when activities requiring alertness are necessary, such as driving a car or operating machinery. You are personally responsible for assessing whether you are in a condition to perform these activities safely. Do not drive or use machines if you feel drowsy, dizzy, or have blurred vision.
How Does Morphine Interact with Other Drugs?
Morphine has numerous clinically significant drug interactions. The most dangerous are combinations with other CNS depressants (benzodiazepines, other opioids, alcohol) which can cause fatal respiratory depression. Always tell your doctor about all medications you are taking, including over-the-counter medicines and herbal supplements.
The simultaneous use of morphine with certain other medications significantly increases the risk of drowsiness, breathing difficulties (respiratory depression), coma, and can be life-threatening. It is critical that your healthcare provider knows about every medication you take.
Major Interactions (Potentially Life-Threatening)
| Drug / Drug Class | Risk | Clinical Advice |
|---|---|---|
| Benzodiazepines (diazepam, alprazolam, etc.) | Severe respiratory depression, coma, death | Avoid combination; if necessary, use lowest effective doses and shortest duration |
| Other opioid analgesics | Additive respiratory depression and sedation | Avoid concurrent use; consult pain specialist |
| Alcohol | Fatal respiratory depression | Absolutely contraindicated during morphine therapy |
| MAO inhibitors | Severe, unpredictable reactions including serotonin syndrome | Do not use within 14 days of MAO inhibitor therapy |
| Barbiturates & sedative-hypnotics | Profound sedation, respiratory depression | Avoid combination; monitor closely if essential |
| Gabapentin / Pregabalin | Increased sedation and respiratory depression | Reduce doses and monitor respiratory function |
Other Significant Interactions
| Drug / Drug Class | Effect | Clinical Advice |
|---|---|---|
| Tricyclic antidepressants (amitriptyline, nortriptyline) | Increased sedation and anticholinergic effects | Monitor for excessive drowsiness; dose adjustment may be needed |
| Rifampicin (anti-tuberculosis) | Reduced morphine effectiveness (enzyme induction) | May require increased morphine dose; monitor pain control |
| Ritonavir (HIV protease inhibitor) | May alter morphine metabolism | Monitor for changes in efficacy or side effects |
| Buprenorphine | Partial agonist may reduce morphine effectiveness | Avoid concurrent use; consult specialist |
| Muscle relaxants (baclofen) | Increased sedation and muscle relaxation | Use lower doses and monitor closely |
| Methylphenidate (ADHD medication) | May alter morphine analgesic effects | Monitor pain control and CNS effects |
| Antacids | May affect morphine absorption | Separate administration times where possible |
What Is the Correct Dosage of Morphine?
Morphine dosage is individually determined by your doctor based on pain severity, prior opioid exposure, age, and organ function. There is no standard “one-size-fits-all” dose. Treatment always starts with the lowest effective dose and is titrated upward as needed. Never change your dose without medical advice.
Morphine dosing requires careful individualization. The correct dose is always the lowest dose that adequately controls pain. Your doctor will discuss the expected treatment goals, duration, and monitoring plan before starting therapy. Dosing depends on whether you are opioid-naive (never taken strong opioids before) or opioid-tolerant (currently receiving opioid therapy).
Adults
Oral Solution (Immediate-Release)
Opioid-naive patients: Typically starting at 5–10 mg every 4 hours as needed. The dose is then individually titrated based on pain response and tolerability.
Cancer pain / palliative care: The starting dose and titration schedule are determined by the treating physician, often starting at 10–20 mg every 4 hours with dose adjustments every 24–48 hours. There is no ceiling dose for cancer pain – the dose is increased until adequate pain relief is achieved or side effects become limiting.
Injectable (Subcutaneous / Intramuscular / Intravenous)
Acute pain: Typically 5–10 mg by subcutaneous or intramuscular injection every 4 hours as needed. Intravenous dosing is administered in hospital settings with appropriate monitoring, usually 2.5–5 mg titrated slowly.
Patient-controlled analgesia (PCA): Typically 1–2 mg bolus with a lockout interval of 5–10 minutes, as directed by the anaesthesia or pain management team.
Elderly Patients
Dose Adjustments for Older Adults
Elderly patients are more sensitive to the effects of morphine due to changes in body composition, liver and kidney function, and increased susceptibility to side effects. Starting doses should be reduced by 25–50% compared to younger adults. Dose titration should be slower, with careful monitoring for respiratory depression and excessive sedation. Renal impairment is common in the elderly and can lead to accumulation of active metabolites.
Children
Pediatric Dosing
Morphine may be used in children under close medical supervision, typically in hospital settings. Doses are calculated based on body weight, usually 0.1–0.2 mg/kg every 4 hours for oral administration. Pediatric dosing must always be supervised by a physician experienced in pediatric pain management. Accidental ingestion of even a small amount by a child can be fatal.
Missed Dose
If you are taking morphine on a regular schedule and miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your normal schedule. Never take a double dose to make up for a forgotten one. If you are unsure, contact your doctor or pharmacist.
Overdose
If you or someone else has taken too much morphine, contact emergency services immediately. A morphine overdose can be fatal.
Signs of overdose include:
- Extremely slow, shallow, or stopped breathing
- Severe drowsiness or inability to stay awake
- Very small (pinpoint) pupils
- Cold, clammy skin
- Blue discoloration of lips or fingernails (cyanosis)
- Loss of consciousness
The antidote naloxone (Narcan) can reverse the effects of a morphine overdose. Individuals at risk of overdose and their family members may be prescribed naloxone to keep at hand. People who have taken an overdose may also develop aspiration pneumonia from inhaling vomit or foreign material into the lungs.
What Are the Side Effects of Morphine?
Like all medicines, morphine can cause side effects. The most common include constipation (affects most patients), drowsiness, nausea, and vomiting. Serious side effects include respiratory depression, severe allergic reactions, and skin reactions. Report any unusual symptoms to your doctor.
Not everyone experiences side effects, and many common side effects (such as nausea and drowsiness) often improve after the first few days of treatment as the body adjusts. However, constipation typically persists throughout treatment and usually requires preventive measures such as laxatives, adequate fluid intake, and dietary fiber. Below is a comprehensive breakdown of morphine side effects by frequency.
Common
- Constipation
- Drowsiness and sedation
- Nausea
- Vomiting
- Urinary urgency or difficulty urinating
- Pupil constriction (miosis)
- Increased ADH secretion
Uncommon
- Biliary and urinary tract spasms
- Mental clouding and confusion
- Mood changes
- Bronchospasm (airway constriction)
- Itching (pruritus)
- Impaired breathing (respiratory depression)
- Dizziness
Rare
- Orthostatic hypotension (dizziness on standing)
- Palpitations or rapid heartbeat
- High or low blood pressure
- Peripheral edema (swelling in extremities)
- Fainting
Frequency Not Known
- Euphoria
- Sleep, memory, and concentration disturbances
- Seizures
- Dry mouth
- Urticaria (hives)
- Muscle twitching (myoclonus)
- Hallucinations and delirium
- Sleep apnea (breathing pauses during sleep)
- Pancreatitis and biliary inflammation (severe upper abdominal pain, nausea, vomiting, fever)
- Hyperalgesia (increased pain sensitivity despite higher doses)
- Sweating
- Withdrawal symptoms or dependence
- Acute generalized exanthematous pustulosis (AGEP) – severe skin reaction with blistering, pustules, and fever
- Severe skin reactions with blistering, widespread peeling, or pustules with fever (signs of AGEP)
- Serious allergic reaction causing difficulty breathing or severe dizziness
- Very slow or shallow breathing
- Severe upper abdominal pain radiating to the back with nausea and fever (possible pancreatitis)
Long-Term Side Effects
Prolonged use of morphine may lead to additional effects that should be monitored:
- Hormonal changes: Reduced production of sex hormones can cause loss of libido, impotence, and missed menstrual periods
- Adrenal insufficiency: Symptoms include weakness, fatigue, loss of appetite, nausea, vomiting, and low blood pressure – hormone supplementation may be needed
- Immune suppression: Long-term opioid therapy may impair immune function
- Opioid-induced hyperalgesia: Paradoxically, chronic opioid use can increase pain sensitivity, requiring dose adjustments or rotation to a different opioid
- Dental health: Oral solutions containing sucrose may contribute to tooth decay with long-term use – brush with fluoride toothpaste twice daily
How Should You Store Morphine?
Store morphine out of sight and reach of children. Keep it below 25°C in a secure location. Do not use after the expiry date. Return unused morphine to a pharmacy for safe disposal – never throw it in household waste or flush it down the drain.
Proper storage of morphine is critically important because of the severe consequences of accidental ingestion, particularly by children. Morphine is a controlled substance and must be stored securely at all times.
- Keep out of sight and reach of children – accidental ingestion of even a small amount can be fatal in children
- Store securely – ideally in a locked cabinet or container to prevent unauthorized access
- Do not use after the expiry date shown on the package (the expiry date refers to the last day of that month)
- Store below 25°C – protect from light and moisture
- Disposal: Do not throw unused morphine in the bin or flush it down the toilet. Return any unused medicine to a pharmacy for safe destruction. This protects both the environment and prevents misuse.
What Does Morphine Contain?
The active substance is morphine hydrochloride. Oral solutions contain 2 mg/ml or 10 mg/ml of morphine hydrochloride. Other ingredients typically include sucrose, citric acid, natural orange flavoring, purified water, and ethanol (15% by volume in oral solutions).
Active Ingredient
Each milliliter of oral solution contains morphine hydrochloride 2 mg/ml (equivalent to morphine 1.5 mg/ml) or morphine hydrochloride 5 mg/ml (equivalent to morphine 3.8 mg/ml), depending on the strength prescribed.
Other Ingredients (Excipients)
The oral solution typically contains sucrose (210 mg/ml), citric acid, natural orange flavoring, purified water, and ethanol (alcohol content 15% by volume). The solution is clear, colorless to slightly yellow, with an orange scent.
Sucrose content: Patients with diabetes should be aware that the oral solution contains sucrose (up to 3.15 g per dose for the 2 mg/ml strength). Long-term use may contribute to tooth decay – brush with fluoride toothpaste twice daily.
Ethanol content: The oral solution contains small amounts of alcohol. The 2 mg/ml solution contains up to 1.7 g of ethanol per dose (at 15 ml). This is unlikely to cause noticeable effects in adults but should be considered in children, pregnant or breastfeeding women, and people with alcohol dependence. The alcohol may also interact with other medications.
Packaging
Morphine oral solution is typically supplied in 500 ml glass bottles with child-resistant closures. Always ensure the cap is properly secured after each use.
Frequently Asked Questions About Morphine
Medical References and Sources
This article is based on current medical research, international guidelines, and approved prescribing information. All claims are supported by scientific evidence from peer-reviewed sources.
- World Health Organization (2018). "WHO Guidelines for the Pharmacological and Radiotherapeutic Management of Cancer Pain in Adults and Adolescents." WHO Guidelines International guideline for cancer pain management including morphine use. Evidence level: 1A
- European Medicines Agency (EMA). "Summary of Product Characteristics: Morphine hydrochloride." EMA European regulatory prescribing information for morphine.
- U.S. Food and Drug Administration (FDA). "Morphine Sulfate Prescribing Information." FDA U.S. regulatory prescribing information including black box warnings.
- British National Formulary (BNF). "Morphine." National Institute for Health and Care Excellence (NICE). BNF - Morphine UK clinical prescribing guidance for morphine.
- Wiffen PJ, et al. (2017). "Oral morphine for cancer pain." Cochrane Database of Systematic Reviews. Cochrane Review Systematic review of oral morphine effectiveness for cancer pain. Evidence level: 1A
- World Health Organization (2023). "WHO Model List of Essential Medicines – 23rd List." WHO Essential Medicines Morphine listed as an essential medicine for pain management.
Evidence grading: This article uses the GRADE framework (Grading of Recommendations Assessment, Development and Evaluation) for evidence-based medicine. Evidence level 1A represents the highest quality of evidence, based on systematic reviews of randomized controlled trials.
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