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Pronunciation: mor' feen
Brand names: Kadian, MS Contin
Dosage forms: oral capsule, extended release (10 mg/12 to 24 hr; 100 mg/12 to 24 hr; 120 mg/24 hours; 20 mg/12 to 24 hr; 30 mg/12 to 24 hr; 30 mg/24 hours; 45 mg/24 hours; 50 mg/12 to 24 hr; 60 mg/12 to 24 hr; 60 mg/24 hours; 75 mg/24 hours; 80 mg/12 to 24 hr; 90 mg/24 hours), ... show all 5 dosage forms
Drug class: Opioids (narcotic analgesics)

Medically reviewed by Sanjai Sinha, MD. Last updated on Apr 8, 2024.

What is morphine?

Morphine is used to treat moderate to severe pain when alternative pain relief medicines are not effective or not tolerated. Morphine is an opioid pain-relieving medication that usually provides significant pain relief for short-term or chronic pain. 

Morphine belongs to a class of medications called opiate (narcotic) analgesics. Morphine works by changing the way the brain and nervous system respond to pain; it does this by binding to the mu-opioid receptors within the central nervous system (CNS) and the peripheral nervous system (PNS).

Morphine is available as oral liquid, tablets, extended-release tablets and capsules, intravenous (IV), suppositories, and epidural.

Morphine may also be abused and may be considered contraindicated in patients with a history of substance abuse or abusing opioids. 

Morphine is a Schedule 2 controlled substance under the Controlled Substances Act (CSA).  This means that morphine has a high potential for abuse but has a currently accepted medical use as a treatment or a currently accepted medical use with severe restrictions. Abuse may lead to severe psychological or physical dependence.

Morphine side effects

Common morphine side effects

Common morphine side effects include drowsiness, dizziness, tiredness, anxiety, nausea, vomiting, stomach pain, gas, or constipation, sweating, low oxygen levels (shortness of breath), feeling light-headed or feelings of extreme happiness or sadness.

Serious morphine side effects

Get emergency medical help if you have signs of an allergic reaction to morphine: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Opioid medicine can slow or stop your breathing, and death may occur, especially if you drink alcohol or use other drugs that cause drowsiness or slow breathing. A person caring for you should give naloxone and/or seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up.

Morphine may cause other serious side effects. Call your doctor at once if you have:

Serious breathing problems may be more likely in older adults and people who are debilitated or have wasting syndrome or chronic breathing disorders.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.


You should not take morphine if you have severe asthma or breathing problems, a blockage in your stomach or intestines, or a bowel obstruction called paralytic ileus.

Morphine can slow or stop your breathing and may be habit-forming. MISUSE OF OPIOID MEDICINE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH, especially in a child or other person using the medicine without a prescription. Keep the medication in a place where others cannot get to it.

Taking opioid medicine during pregnancy may cause life-threatening withdrawal symptoms in the newborn.

Fatal side effects can occur if you use morphine with alcohol or with other drugs that cause drowsiness or slow your breathing.

Before taking this medicine

You should not take this medicine if you have ever had an allergic reaction to morphine or other opioid medicines or if you have:

To make sure morphine is safe for you, tell your doctor if you have ever had:

Tell your doctor if you also use stimulant medicine, other opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. An interaction with morphine could cause a serious condition called serotonin syndrome.


Morphine may harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant. If you use morphine during pregnancy, your baby could be born with life-threatening withdrawal symptoms and may need medical treatment for several weeks.

Long-term morphine use may affect fertility in men or women. Pregnancy could be harder to achieve while either parent is using this medicine.


Do not breastfeed when using morphine, as morphine in breast milk can cause life-threatening side effects in a nursing baby.

How should I take morphine?

Take morphine exactly as prescribed by your doctor. Follow the directions on your prescription label and read all medication guides or instruction sheets. Never use morphine in larger amounts or for longer than prescribed. Tell your doctor if you feel an increased urge to use more morphine.

Never share opioid medicine with another person, especially someone with a history of drug addiction. MISUSE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH. Keep the medicine where others cannot get to it. Selling or giving away this medicine is against the law.

Never crush a pill to inhale the powder or inject it into your vein. This could result in death.

Swallow the extended-release capsule or tablet whole to avoid exposure to a potentially fatal overdose. Do not crush, chew, break, open, or dissolve.

Measure liquid medicine with the supplied measuring device (not a kitchen spoon).

Call your doctor if your symptoms do not improve or if they get worse.

You should not stop using morphine suddenly. Stopping suddenly may cause withdrawal symptoms. Ask your doctor before stopping the medicine.

Your dose needs may change if you switch to a different brand, strength, or form of this medicine. Avoid medication errors by using only the medicine your doctor prescribes.

Do not keep leftover medicine. Just one dose can cause death for someone using it accidentally or improperly. Ask your pharmacist about a drug take-back program,or flush the unused medicine down the toilet.

Store tightly closed at room temperature, away from moisture, heat, and light. Keep your medicine in a place where no one can use it improperly.

What happens if I miss a dose?

Since morphine is used for pain, you are not likely to miss a dose. Skip any missed dose if it is almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose can be fatal, especially in a child or person using opioid medicine without a prescription. Overdose symptoms may include severe drowsiness, pinpoint pupils, slow breathing, or no breathing.

Your doctor may recommend you get naloxone (a medicine to reverse an opioid overdose) and keep it with you at all times. A person caring for you can give the naloxone if you stop breathing or don't wake up. Your caregiver must still get emergency medical help and may need to perform CPR (cardiopulmonary resuscitation) on you while waiting for help to arrive.

Anyone can buy naloxone from a pharmacy or local health department. Make sure any person caring for you knows where you keep naloxone and how to use it.

What should I avoid while taking morphine?

Do not drink alcohol. Dangerous side effects or death could occur.

Avoid driving or hazardous activity until you know how morphine will affect you. Dizziness or drowsiness can cause falls, accidents, or severe injuries. Also avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

What other drugs will affect morphine?

Many other drugs can be dangerous when used with opioid medicine. Tell your doctor if you also use:

This list is not complete and many other drugs may affect morphine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

General information

Mighty Morphin Power Rangers is unrelated to the medication morphine. In the Power Rangers series, “Morphin” refers to the transformation sequence when the characters change into their superhero forms.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use morphine only for the indication prescribed.

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