Morphine / naltrexone Side Effects

Not all side effects for morphine / naltrexone may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to morphine / naltrexone: oral capsule extended release

In addition to its needed effects, some unwanted effects may be caused by morphine / naltrexone. In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking morphine / naltrexone:

More common
  • Bloating or swelling of the face, arms, hands, lower legs, or feet
  • chills
  • confusion
  • constipation
  • drowsiness
  • feeling of warmth
  • irritability
  • mental depression
  • rapid weight gain
  • redness of the face, neck, arms, and occasionally, upper chest
  • relaxed and calm
  • restlessness
  • sleepiness
  • sudden sweating
  • tingling of the hands or feet
  • trembling or shaking of the hands or feet
  • unusual weight gain or loss
  • Abnormal dreams
  • being forgetful
  • blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • clumsiness or unsteadiness
  • confusion about identity, place, and time
  • darkened urine
  • decrease in frequency or volume of urination
  • decreased awareness or responsiveness
  • delusions
  • dementia
  • difficult or labored breathing
  • difficult or painful urination
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
  • fast heartbeat
  • feeling of warmth
  • fever
  • indigestion
  • loss of appetite
  • nausea
  • nervousness
  • pains in the stomach, side, or abdomen, possibly radiating to the back
  • redness of the face, neck, arms, and occasionally, upper chest
  • seeing, hearing, or feeling things that are not there
  • severe nausea or vomiting
  • severe sleepiness
  • sweating
  • tightness in the chest
  • unusual tiredness or weakness
  • vomiting
  • yellow eyes or skin

Some of the side effects that can occur with morphine / naltrexone may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Acid or sour stomach
  • anxiety
  • belching
  • decreased appetite
  • diarrhea
  • difficulty with moving
  • excess air or gas in the stomach or intestines
  • full feeling
  • heartburn
  • itching skin
  • muscle pain or stiffness
  • muscle spasm
  • pain in the joints
  • passing gas
  • sleepiness or unusual drowsiness
  • stomach discomfort or upset
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • weight loss
  • Cold sweats
  • dizziness
  • dry mouth
  • general feeling of discomfort or illness
  • headache
  • inability to have or keep an erection
  • increased sweating
  • lack or loss of strength
  • loss in sexual ability, desire, drive, or performance
  • night sweats
  • pressure in the stomach
  • rash
  • stomach tenderness
  • swelling of the abdominal or stomach area
  • trouble sleeping
  • upper abdominal or stomach pain

For Healthcare Professionals

Applies to morphine / naltrexone: oral capsule extended release


Gastrointestinal side effects including constipation (up to 31.2%), nausea (up to 22.2%), vomiting (up to 8.4%), diarrhea (up to 7%), dry mouth (up to 5.7%), upper abdominal pain (up to 2.3%), dyspepsia, flatulence, stomach discomfort, abdominal distension, pancreatitis, abdominal discomfort, fecaloma, lower abdominal pain, and abdominal tenderness have been reported.

Nervous system

Nervous system side effects including somnolence (up to 13.9%), dizziness (up to 7.7%), headache (up to 6.9%), lethargy, sedation, tremor, depressed level of consciousness, mental impairment, memory impairment, disturbance in attention, stupor, paraesthesia, and abnormal coordination have been reported.


Dermatologic side effects including pruritus (up to 6.2%), hyperhidrosis (up to 3.4%), rash, piloerection, cold sweat, and night sweats have been reported.


General side effects including fatigue (up to 4.1%), chills, peripheral edema, irritability, malaise, asthenia, jittery feeling, and drug withdrawal syndrome have been reported.


Psychiatric side effects including insomnia (2.9%), anxiety (up to 2.2%), depression, restlessness, disorientation, abnormal thinking, mental status changes, confusional state, euphoric mood, hallucination, abnormal dreams, mood swings, and nervousness have been reported.


Cardiovascular side effects including flushing (up to 2.3%), hot flush, and hypotension have been reported.[Ref]


Metabolic side effects including anorexia and decreased appetite have been reported.


Musculoskeletal side effects including arthralgia, muscle spasms, myalgia, and muscular weakness have been reported.


Ocular side effects including blurred vision have been reported.


Hepatic side effects including increased ALT and increased AST have been reported.


Renal side effects including urinary retention and dysuria have been reported.


Genitourinary side effects including erectile dysfunction have been reported.


Respiratory side effects including dyspnea and rhinorrhea have been reported.


1. "Product Information. Embeda (morphine-naltrexone)." King Pharmaceuticals Inc, Bristol, TN.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.