Morphine Side Effects, Interactions, & Warnings

Morphine may help with pain relief but it also comes with several adverse effects. These side effects range from mild to severe and some last for a short period of time while others can be long-term.

Morphine is an opioid medication used to treat moderate to severe pain, acute and chronic pain, and neonatal abstinence syndrome. It can be found under the brand names Arymo ER, Avinza, Kadian, Morphabond, MS Contin, Oramorph SR, and Roxanol-T.

It works by binding to opioid receptors in the brain and changing how the central nervous system responds to pain. It’s primarily taken orally or intravenously (as morphine sulfate).

This pain medication is classified as a schedule II controlled substance by the DEA, which means it has a high potential for abuse and can lead to tolerance, physical and psychological dependence, opioid use disorder/addiction, and other serious side effects.

Morphine Side Effects

Morphine may help with pain relief but it also comes with several adverse effects. These side effects range from mild to severe and some last for a short period of time while others can be long-term.

Short-Term Side Effects

Some short-term effects of morphine use or abuse may include:

  • nausea/vomiting
  • constipation
  • itching
  • loss of appetite
  • small pupils
  • difficulty urinating
  • respiratory depression
  • mood changes
  • tiredness
  • gastrointestinal dysfunction
  • changes in heart rate
  • erectile dysfunction
  • sleep apnea
  • dry mouth
  • chest pain

Long-Term Side Effects

Long-term symptoms of morphine use can include:

  • chronic constipation
  • poor appetite
  • heartburn
  • bloating
  • stomach pain
  • weight loss
  • increased blood sugar
  • menstruation issues
  • immune-related problems
  • physical dependence

Morphine Drug Interactions

Several drugs interact with morphine in dangerous ways. If you use any of the following medications or substances, please tell your healthcare provider:

  • alcohol
  • other opioids for pain management or prescription cough medicine
  • sedatives/benzodiazepines like Valium (diazepam), Ativan (lorazepam), Klonopin (clonazepam), Restoril (temazepam), and Xanax (alprazolam)
  • sleeping pills
  • muscle relaxers
  • tranquilizers
  • antipsychotic medicine
  • drugs that affect serotonin levels including stimulants, medicine for depression, Parkinson’s disease, migraine headaches, or serious infections
  • certain supplements
  • MAO inhibitors including isocarboxazid, linezolid, and methylene blue

Morphine Warnings

There are also certain warnings that come with morphine that you should be aware of. They include allergies, how the drug affects pregnancy, how it affects some pre-existing conditions, and the risk for overdose and withdrawal symptoms.


If you have an allergic reaction to morphine, you may experience symptoms like:

  • rash
  • hives
  • itching
  • red, swollen, blistered, or peeling skin
  • wheezing
  • tightness in chest or throat
  • trouble breathing
  • difficulty swallowing
  • unusual hoarseness
  • swelling of the mouth, face, lips, tongue, or throat

Pre-Existing Conditions

Morphine can also make some pre-existing conditions worse, including:

  • breathing problems
  • sleep apnea
  • head injury
  • brain tumor
  • seizures
  • low blood pressure
  • drug or alcohol addiction
  • mental illness
  • urination problems
  • liver or kidney disease
  • gallbladder, pancreas, or thyroid problems


If you use morphine while pregnant, it could lead to your baby becoming dependent on the drug. Once they’re born, they could experience life-threatening withdrawal symptoms.

Withdrawal symptoms in newborns can look like high-pitched crying, sleep problems, seizures, irritability, trembling, and poor feeding behavior.

Taking morphine while breastfeeding can also negatively affect your baby. Small amounts of the drug can transfer into your breast milk and then the baby. If they receive too much, they could experience trouble breathing or severe drowsiness.

Morphine Overdose Symptoms

If you’re taking a high dose of morphine or mixing the prescription drug with other substances, you have an increased risk of a morphine overdose.

If you or a loved one are worried about an overdose, the symptoms to look out for include:

  • pinpoint or small pupils
  • decreased responsiveness
  • extreme drowsiness
  • increased blood pressure
  • increased thirst
  • lower back or side pain
  • muscle cramps
  • swelling of the face, fingers, or lower legs
  • shallow breathing

If a healthcare professional prescribes you morphine, make sure to talk to them about having naloxone (Narcan) on hand. It can reverse the effects of an overdose almost instantly.

Withdrawal Symptoms

If you’ve taken morphine for a long period of time or abused it in high doses, you’re likely to build up a physical dependence. If you’ve built up a physical dependence and try to stop use, you’ll likely experience withdrawal symptoms that may include:

  • drug cravings
  • trouble sleeping
  • depression
  • body aches
  • nausea/vomiting
  • vomiting
  • moodiness
  • restlessness
  • teary eyes
  • loss of appetite
  • stomach cramps
  • fast heartbeat
  • fast breathing

Because the morphine withdrawal process can lead to some serious symptoms, it’s not recommended to quit the pain control drug by yourself. Your doctor can guide you through a tapering process or you can enter a detox program.

Morphine Addiction Treatment

If you or a loved one lives with a morphine addiction, you don’t have to deal with it alone. Northeast Addiction Treatment Center offers medication-assisted treatment, outpatient services like intensive outpatient and partial hospitalization programs, and specialized forms of therapy.

To start your recovery journey, please call our helpline today.

Written by
Northeast Addition Editorial Team

©2023 Northeast Addition Center | All Rights Reserved

This page does not provide medical advice.

Ready to make a change? Talk to a specialist now.