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Morphine Sulfate
Christopher Dolinsky, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: July 21, 2004
Intravenous
How It Is Given:
Intravenous (IV) morphine is given through a patient's vein by a nurse or doctor. In order to get morphine this way, a patient must have an IV. Morphine is in a class of drugs call opioids (O-pee-oids) or narcotics. When morphine is injected, it provides quick and effective pain relief. It is used to treat breakthrough pain in cancer patients who have been receiving opioids on a regular basis to treat their baseline pain.
How It Works:
When morphine is injected, it is immediately absorbed into the body. It will begin working to relieve pain almost instantly, although it reaches its peak effect in 5 to 10 minutes. It will continue to work for 2 to 4 hours. Morphine and all opiate painkillers work by activating certain receptors in the brain that cause pain relief. Opiate painkillers are the strongest class of painkillers known to mankind.
Side Effects and Precautions
Side effects to morphine and all other opiate medications are related to the receptors that these medications activate to cause their pain relief. When someone first begins taking morphine and other opiates, they will probably experience many of the side effects. However, as a person gets used to these medications, a lot of the unpleasant side effects will disappear.
Common Side Effects
Nausea or vomiting
This is a very common side effect for people who begin taking morphine/opioids for the first time. Eating small frequent meals, sucking hard candy, or chewing gum may help. Nausea is usually very mild and subsides after a few days. If your nausea persists, talk to your doctor about ways to relieve it.
Sleepiness (somnolence)
Feeling sleepy, drowsy or lightheaded may accompany the use of opioid painkillers. Some people just don't "feel like themselves" on these medications. Avoid driving or any other potentially dangerous tasks that require your concentration and a clear head until you feel normal again. Avoid alcohol or other sedatives while using these medications unless they are specifically prescribed by your doctor. Most people will begin to feel like themselves after a few days on the medications. If you continue to feel "out of it" after a couple of days, talk to your doctor about adjusting your dosages.
Constipation
Constipation will happen to just about every patient who takes morphine or other opioids for any significant length of time. More liquids, regular exercise, or a fiber-containing diet may help. Talk with a healthcare provider about a stool softener or laxative if you haven't already been taking one.
Uncommon Side Effects
Slowed Breathing or Low Blood Pressure
You may experience low blood pressure or slowed breathing while taking morphine or any other opioid painkillers. This usually only occurs when the dose of medication is too high or it is increased too quickly. This rarely happens to patients who have been taking opioid medications for a long time.
These side effects can also result from an overdose of morphine or other opioids. If you suspect that you or someone you know has taken an overdose of morphine or other opioids, call 911 immediately. If you feel extremely tired, lightheaded, dizzy, sweaty, nauseated, or short of breath, you need to see a doctor immediately. Sometimes patients who have taken too much morphine or other opioid medications will be so sleepy that they can't be awakened or aroused. These side effects are emergency situations. If any of these symptoms occur, you should seek emergency medical attention.
Allergic Reaction
Although it is uncommon, some people are allergic to certain opioid preparations. If after taking morphine or other opioids, you experience chest tightness, swelling, wheezing, fever, itching, blue skin color or cough, you need to call 911. These side effects are emergency situations. If any of these symptoms occur, you should seek emergency medical attention.
Tolerance, Dependence and Addiction
Just as a person on long-term opioids stops experiencing some of their negative side effects after a while, they may also stop getting proper pain relief. This phenomenon is called tolerance. As patients develop tolerance, they will need higher doses of their opioids to get adequate levels of pain relief. Tolerance is a completely normal aspect of using opioid painkillers, and is nothing to be concerned about. The point of using these medications is to keep pain well controlled; therefore the exact doses that any patient requires are not important as long as they can be kept comfortable.
As a person remains on opioids for a long time, their bodies will begin to adapt to the medications. This causes tolerance, but it can also cause dependence. Dependence means that the body "gets used to" the opioids. Dependence DOES NOT equal addiction. Dependence is a natural, physical phenomenon that happens to everyone on long-term opioid therapy. The only important thing to know about dependence is that once a patient becomes dependent on opioids, they will feel very sick if they stop them abruptly. Patients who are dependent on opioids and stop them all of the sudden will feel lousy, like they have the flu. This is called withdrawal. The way to combat withdrawal is to take someone off of opioids very slowly, not all at once. It is important to remember that dependence and withdrawal are normal, and happen to everyone who takes opioids for a long period of time.
Many people who are prescribed morphine or other opioid pain relievers are worried that they may become addicted to these medications. This fear stems from the fact that opioid medications can cause euphoria and pleasure when used by people who are not in any pain. However, when these medications are used to treat physical pain, it is extremely unlikely that patients will become addicted to them. Addiction is a psychological problem that very rarely affects people who take opioids for pain control. "Feeling high" from opiates does not happen to people who take them for pain control. However, pain-free people who abuse opioids for fun can run into problems with addiction.