Opium use for pain relief has a long history. People started using opium around 3500 B.C. Through the ages, it’s been known as a universal cure-all.

In 1803, morphine was isolated from opium, making it one of the first medications made from the plant. It gained popularity quickly and was widely used for all types of pain relief.

But one of its side effects soon became clear: dependence. During the American Civil War, this side effect became more widely known, as many soldiers developed morphine dependence.

Morphine and other opioids have serious side effects. They have to be understood and managed so patients can get the full benefits with fewer risks.

Let’s take a closer look at morphine and its effects.

According to the Centers for Disease Control and Prevention (CDC), around 11 percent of adults in the United States experience pain every day.

Studies show 10 to 60 percent of Americans who undergo common surgeries have chronic pain after their procedure. This pain affects their daily life and wellness.

Morphine is used to ease both acute (immediate) and chronic (long-lasting) pain.

However, morphine has serious side effects. Doctors consider these every time they prescribe it. These side effects are especially significant for people with other health concerns.

There are four types of opioid receptors in several areas of your body. Among them are receptors in the brain, gastrointestinal (GI) tract, and spinal cord. How strongly opioids bind to these receptors determines the level of benefits versus the number of side effects you may experience.

In the brain, morphine helps release the neurotransmitter dopamine. This blocks pain signals and creates a pleasurable feeling. It’s why morphine works as a pain reliever.

Morphine is available in oral and injectable forms. Your doctor decides which type to prescribe based on the level of your pain and what’s safest for you.

Today, there are CDC guidelines for safe and effective pain management for chronic pain. These guidelines were specifically developed to help lower the risk of overdose and misuse of opioids.

Oral morphine

Oral morphine is available in both immediate-release and long-acting forms. For chronic pain, doctors generally prescribe long-acting products.

Your doctor will decide which formulation and dosage is best using many factors, such as:

  • your history with opioid medications
  • the level and type of pain
  • your age
  • other health conditions (kidney function, heart or lung problems, sleep apnea, low blood pressure, seizures, stomach problems, etc.)
  • other medications you’re using
  • other factors, such as sensitivity to morphine

Injectable morphine

Injectable morphine is available as a solution that can be:

  • injected under the skin (subcutaneous)
  • into a muscle (intramuscular)
  • into a vein (intravenous)

This type of morphine is only administered with medical supervision. Your doctor will choose your specific treatment and dosage based on your level of pain and the potential side effects.

Injectable morphine has more risks than oral versions. Your doctor will discuss these risks with you before starting the medication.

The side effects you experience when using opioids like morphine will depend on factors such as dosage, strength, and how long you use the medication.

When you first start taking morphine, you may experience side effects. If you have unusual or new symptoms, be sure to keep track of them. Discuss them with your pharmacist or doctor.

possible short-term side effects of morphine
  • nausea and vomiting
  • constipation
  • itching
  • loss of appetite
  • lower body temperature
  • difficulty urinating
  • slow breathing
  • sleepiness
  • changes in heart rate
  • weakness
  • dizziness upon standing up
  • confusion
  • nervousness
  • erectile dysfunction

Morphine is usually not the first choice for chronic, noncancer pain. The risks of dependence and overdose are a serious concern. According to the CDC, 1 in 4 patients who are treated with opioids long term develop opioid use disorder.

Long-term morphine use can cause side effects in several ways by disturbing your GI tract, hormones, and immune system.

possible long-term side effects of morphine

Issues related to the GI tract include:

  • chronic constipation
  • poor appetite
  • reflux
  • bloating
  • stomach pain
  • dry mouth
  • weight loss

Issues related to hormonal changes include:

  • increased blood sugar
  • problems with menstruation
  • osteoporosis and risk of fractures
  • immune-related problems, like risk of infection
  • sexual dysfunction


If you use morphine for a longer period of time, you may need higher or more frequent doses to get the same pain-relief effects.


If your body becomes tolerant to morphine, it doesn’t mean you’re tolerant to other opioids. If your doctor switches you to another opioid, they must calculate a new dose to avoid an overdose. Don’t change your dose without talking with your doctor.

Physical dependence

If you use morphine, your body may get used to it. You may be unable to function normally without morphine.

Opioid use disorder

Opioids, like morphine, can create very strong, feel-good feelings. Some people may misuse morphine, like taking more than their prescribed dose, to increase these desired effects.

They may begin to compulsively use the drug, even if it’s harming or interfering with their health, job, or relationships. This is opioid use disorder, or addiction.


Alcohol, marijuana, or other central nervous system depressant drugs can increase the risk of overdose and other side effects. Don’t drink alcohol or take other drugs while using morphine. Discuss all the medications and supplements you take with your doctor, including over-the-counter ones, before you start any prescription medication.

Withdrawal symptoms

You can’t suddenly stop taking morphine if you’ve been using it for a while. Withdrawal effects can be serious.

morphine Withdrawal symptoms
  • anxiety
  • runny nose
  • sweating
  • drug cravings
  • thoughts of suicide
  • trouble sleeping
  • depression
  • agitation
  • body aches
  • nausea and vomiting
  • diarrhea
  • cramping
  • moodiness
  • lack of concentration

If your doctor prescribes you morphine, be sure to tell them if:

  • your side effects are bothering you too much to continue using the medicine
  • your pain isn’t better
seek medical care immediately

Call your doctor or seek medical care right away if you develop:

  • a rash
  • fainting
  • difficulty breathing
  • seizures
  • itching
  • swelling of your throat, face, or tongue

One of the most bothersome side effects of using morphine and other opioids is opioid-induced constipation. Research estimates one-third of patients reduce their medication dose or stop using opioids altogether because of this side effect.

Here are some ways to manage opioid-induced constipation:

  • Take extra fiber as a supplement.
  • Increase the fiber in your diet.
  • Get regular exercise.
  • Drink extra fluids.
  • Take laxatives when needed. However, this isn’t always helpful; consult your doctor for advice.
  • Take a prescription medication that blocks opioid receptors in the gut, such as:
    • methylnaltrexone (Relistor)
    • lubiprostone (Amitiza)
    • naloxegol (Movantik)
    • naldemedine (Symproic)

Until you get used to the side effects of morphine:

  • Don’t stand up suddenly to avoid dizziness or fainting.
  • Avoid driving or doing any tasks that require focus or concentration.

There are risks to using morphine, including overdose. In some cases, overdose can be fatal.


Call 911 immediately if you suspect a morphine overdose. Signs include slowed breathing, extreme fatigue, and unresponsiveness. Wait with the person until help arrives. Try to keep them awake.

People have a higher risk for overdosing if they:

  • are older
  • have poor kidney or liver function
  • have emphysema
  • have sleep apnea
  • use other drugs that increase morphine’s effects, such as benzodiazepines like alprazolam (Xanax)

In some cases, morphine overdose can be reversed with a medication called Narcan or Evzio. These are brand names of the drug naloxone. It blocks the opioid receptors in the brain.

If you’ve been using morphine for a long time, administering naloxone may cause immediate withdrawal symptoms. Your doctor must manage these symptoms.

If an individual overdoses while using a long-acting type of morphine, they may need multiple doses of naloxone. It may take days for the morphine to clear their body.

After an overdose, a person may still have serious complications, even if they’re given naloxone. They may need medical monitoring for a while.

Morphine is an effective opioid medication used to treat moderate to severe short- and long-term pain.

Your doctor will discuss the risks versus benefits of using morphine for your individual case.

Talk to your doctor about the side effects of using morphine, including overdose. Have a family member or friend learn the signs of overdose and what to do in case of one. It’s a good idea to have naloxone on hand in case of emergency.