Morphine Side Effects

by on June 19, 2012


A potent pain reliever, morphine side effects are typically worth the risk in cases when this medication is prescribed. Common side effects of Morphine include loss of appetite, nausea, headache, and memory problems, but in rare cases the drug can cause fainting, seizures, and a dangerously slow heartbeat. Morphine has the potential to become habit forming and should only be used as directed.

Common Morphine Side Effects

Because of the drug’s potency, it is not uncommon for individuals to experience some mild to moderate side effects while taking morphine. Some of the most frequently reported side effects of morphine include:

  • Dizziness
  • Lightheadedness
  • Drowsiness
  • Weakness
  • Headache
  • Nausea
  • Vomiting
  • Diarrhea or constipation
  • Changes in taste
  • Loss of appetite
  • Weight loss
  • Unexplained sweating
  • Dry mouth
  • Stiff muscles
  • Confusion, nervousness, or agitation
  • Vision changes or double vision
  • Uncontrollable shaking or tremors
  • Sleep difficulties or insomnia
  • Unexplained changes in mood
  • Red eyes with small pupils
  • Flu like symptoms
  • Difficult or painful urination
  • Decreased libido or inability to perform

If any of these side effects are severe or become continuous, contact your doctor. Many patients continue their treatment with morphine because the benefits the pain reliever provides outweighs any additional discomforts that may occur.

Serious Morphine Side Effects

Morphine users have a chance of experiencing more serious side effects while taking the medication. The biggest concern is addiction or dependency. Serious allergic reactions can also occur, and in larger doses, there is a potential for possibly fatal complications. Individuals who have a hypersensitivity to morphine can experience sudden death with less than half of a lethal dose. If you experience any of the following side effects, contact your doctor or another medical professional immediately.

  • Sudden vision changes or blurred vision
  • Severe dizziness or fainting
  • Fast, slow, or irregular heartbeat
  • Shallow, slow, or difficult breathing
  • Blue or purplish skin color
  • Seizures
  • Hives or a skin rash
  • Unexplained itching
  • Difficulty swallowing
  • Swelling of the extremities or lower legs
  • Hallucinations
  • A tight feeling in the throat

Until you know how your body will react to morphine, do not drive or perform tasks that require concentration. Report any unusual changes in your physical or mental state while taking morphine to your doctor immediately, even if the side effects are not mentioned here.


Significant evidence does not exist to determine whether or not morphine can harm an unborn child if taken during pregnancy. Morphine is categorized as a pregnancy category C drug by the FDA and is not recommended for use by pregnant women unless it is absolutely necessary. This may result in addiction or withdrawal symptoms in the newborn at birth. Morphine will pass through breast milk and can be dangerous to infants. Talk to your doctor about the risks of morphine if you are pregnant or plan to become pregnant and do not use morphine while breastfeeding.

Existing Conditions

Some people are more likely to experience serious side effects while taking morphine because of certain preexisting conditions. Let your doctor know if you suffer from any of the following:

  • A history of alcohol or drug addiction
  • Breathing disorders, including sleep apnea, COPD, asthma, etc.
  • An underactive thyroid
  • Liver, kidney, or gallbladder disease
  • Conditions that may cause seizures like epilepsy
  • Brain tumors or a history of head injuries
  • Curvature of the spine
  • Low blood pressure
  • A mental disorder
  • Urination difficulties or an enlarged prostate
  • Adrenal gland disorders such as Addison’s disease
  • Digestive tract blockage

Morphine Withdrawal

The potential to become physically and psychologically dependent on morphine is very high. Tolerance to the drug is built quickly and it is not uncommon for long term users to experience mild withdrawal symptoms in between their regular doses. Mild side effects may include:

  • Anxiety
  • Irritability
  • Sweating
  • Craving

The final stages of withdrawal can include more severe side effects, ranging from excessive vomiting and diarrhea to changes in blood cell counts. In rare cases, patients have experienced heart attacks, strokes, seizures, and fatal levels of dehydration during morphine withdrawal. Suicide attempts have also resulted. Individuals who use morphine over an extended period should discuss a cessation plan with their doctor to avoid these side effects.

Morphine is a very potent pain reliever that should only be prescribed when other narcotics fail to provide relief. Morphine side effects are generally not severe, but caution should be taken to be sure an individual can tolerate an opiate like morphine before treatment is started.