Morphine Side Effects: Brand names: Avinza, Kadian, MS Contin, Roxinol, Oramorph and Morphine IR. Dosage forms: morphine sulfate is available in immediate release tablets of 15 and 30 mg, in extended release dosages of 15, 30, 60, 100 and 200 mg; as 2, 4 and 20 mg/ml. solution, as 5, 10, 20 and 30 mg rectal suppositories, and for subcutaneous, intramuscular and intravenous injection. Indications: Morphine sulfate is one of the oldest medications known to man, and has many indications with FDA approval including for unstable angina pectoris, acute MI, as an adjuvant therapy for acute pulmonary edema, for moderate to severe pain management, and for neonatal opioid withdrawal.

Black Box Warning: The black box warnings for Morphine sulfate are related to it’s abuse potential and overdose issues. Morphine sulfate is a Schedule II controlled substance that is an opioid agonist. (an agonist is a substance that leads to the positive stimulation of a receptor as opposed to an antagonist which blocks the receptor from stimulation by an agonist) Morphine has the risks of misuse, abuse or diversion. The extended release products are only for treatment of chronic pain and should be dosed regularly, not as needed. The extended release formulations should not be chewed, cut, broken or dissolved because severe and potentially fatal overdose can occur. The solution, especially the 20 mg/ ml should be used only in opioid tolerant patients, as death can occur from overdose if used in opioid naïve patients. Similar overdose concern is noted with the higher 100 mg ER and 200 mg ER dose forms. These also are only for use in opioid tolerant patients.

Common Morphine Side Effects: Morphine side effects occur in almost everyone who uses the medication at least to a minor degree. Sedation is an anticipated and expected morphine side effect. This can be severe and known as somnolence. Constipation is also very common and is due to the opioid mu receptors in the bowel wall where stimulation leads to increased churning of the bowel contents without effective propulsion of the stool. The opioid mu receptors in the GI tract can also lead to nausea, vomiting, abdominal pain, and biliary spasm. Dry mouth, itching, urinary retention, very small pupils called miosis, a sense of doom called dysphoria is fairly common and low blood pressure and dizziness can occur.

Life Threatening Morphine Side Effects: The biggest risk of any opioid medication use is respiratory depression that can lead to severe hypoventilation, apnea and death. Death can be the result of myocardial infarction, seizures, shock, or severely slow heart rate (bradycardia). Severe morphine side effects can include bowel problems including toxic megacolon and paralytic ileus. Acute withdrawal symptoms can be severe if morphine is stopped suddenly after regular use. Neonatal withdrawal is expected after birth to a mother who has used morphine regularly in the period prior to birth.

Unusual Morphine Side Effects: The abdominal cramps and pain that are seen as morphine side effects can be especially disturbing when morphine is used to treat abdominal pain. The severity of the constipation, and the lack of response to fiber products can be very frustrating. Usually opioid induced constipation needs to be treated with a combination of a gentle stimulant laxative like senna and a stool softener like docusate.

Drug Interactions: Morphine should be used with caution in combination with any other drugs that depress the central nervous system. Morphine is contraindicated for use with ethanol, tipranavir (an HIV drug). It should be used very cautiously with any other opioid agonists or antagonists. The list of potential drug interactions is extensive and you should refer to the manufacturer’s prescriber information for details.

Pregnancy and Lactation Class: Pregnancy category C, and considered probably safe in lactation.

Special Considerations: Like all opioid medications the potential for abuse, misuse, and diversion is considerable. Use if there is a history of drug or alcohol abuse is best avoided when possible. Keeping the medication out of the reach of children, and safe from theft or diversion is important. Always keep in mind the respiratory depression and overdose morphine side effects and use only as prescribed.

Morphine potency is the standard against which all other opoiod pain medications are measured against.  A term known as the “morphine equivalent dosage” or MED is typically used to calculate the total opioid dosage a patient is using.  For example if a patient is taking long acting morphine like MS Contin 100 mg twice daily for chronic pain and oxycodone 10 mg for breakthrough pain the total morphine equivalent daily dosage would be 100 + 100 for the two MS Contin 100 mg tablets plus the number of mg. daily of oxycodone takens multiplied by 1.5, since the MED of oxycodone is 1.5x.  So if this patient were taking 3 of the oxycodone 10 mg daily in addition to the 200 mg of morphine the MED would be 245.  This equivalency is very helpful when switching a patient from one opioid to another, and when considering tapering off opioids.

Other MED calculations include

Hydrocodone 1 mg = Morphine 1 mg

Hydromorphone (dilaudid) 1 mg = morphine 4 mg

Fentanyl Patch 1 mcg/ hr = 2.4 mg morphine daily

Codeine 10 mg = Morphine 1.5 mg



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