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Pain (PDQ®)

  • Last Modified: 04/10/2014

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Using Drugs to Control Pain



The doctor will prescribe drugs based on whether the pain is mild, moderate, or severe.

Your doctor will prescribe drugs to help relieve your pain. These drugs need to be taken at scheduled times to keep a constant level of the drug in the body to help keep the pain from coming back. Drugs may be taken by mouth or in other ways, such as by infusion or injection.

Your doctor may prescribe extra doses of a drug that can be taken as needed for pain that occurs between scheduled doses of drug. The doctor will adjust the drug dose for your needs.

Acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) may be used to relieve mild pain.

NSAIDs help relieve mild pain. They may be given with opioids for moderate to severe pain. Acetaminophen also relieves pain, although it does not have the anti-inflammatory effect that aspirin and other NSAIDs do.

Patients, especially older patients, who are taking acetaminophen or NSAIDs need to be closely watched for side effects. See Treating Pain in Older Patients for more information. Most NSAIDs affect the blood platelets so that it takes longer for blood to clot and stop any bleeding. Aspirin should not be given to children to treat pain.

Opioids may be used to relieve moderate to severe pain.

Opioids work very well for the relief of moderate to severe pain. Some patients with cancer pain stop getting pain relief from opioids during long-term therapy. This is called tolerance. Larger doses or a different opioid may be needed if your body stops responding to the same dose. Tolerance of an opioid is a physical dependence on it. This is not the same as addiction (psychological dependence). Opioid doses can be safely increased by your doctor as needed for your pain, without causing addiction.

There are several types of opioids:

The doctor will prescribe drugs and the times they should be taken in order to best control your pain.

Most patients with cancer pain will need to receive opioids on a regular schedule.

Receiving opioids on a regular schedule helps manage the pain and keeps it from getting worse. The amount of time between doses depends on which opioid is being used. The correct dose is the amount of opioid that controls your pain with the fewest side effects. The dose will be slowly adjusted until there is a good balance between pain relief and side effects. If opioid tolerance does occur, it can be overcome by increasing the dose or changing to another opioid.

Sometimes, the opioid dose needs to be decreased or the opioid is stopped. This may be done when you no longer have pain because of treatments such as nerve blocks or radiation therapy. The doctor may also decrease the dose if it makes you too sleepy or if your kidney function decreases.

Opioids may be given in different ways.

Opioids may be given by the following ways:

  • Mouth: If your stomach and intestines work normally, medicine is usually given by mouth. Opioids given orally are easy to use and usually low-cost. Oral opioids are sometimes placed under the tongue or on the inside of the cheek to be absorbed.

  • Rectum: If you cannot take opioids by mouth, they may be given as rectal suppositories.

  • Skin patches: Opioid patches are placed on the skin.

  • Nose spray: Opioids may be given in the form of a nasal spray.

  • Intravenous (IV) line: Opioids are given into a vein only when simpler and less costly methods cannot be used, don't work, or are not wanted by the patient. Patient-controlled analgesia (PCA) pumps are one way to control pain through your IV line. A PCA pump allows the patient to control the amount of drug that is used. With a PCA pump, you can receive a preset opioid dose by pressing a button on a computerized pump that is connected to a small tube. Once the pain is controlled, the doctor may prescribe regular opioid doses based on the amount you used with the PCA pump.

  • Subcutaneous injection: Opioids are given by injection into the fatty layer of tissue just under the skin. The small needle used for the injection may be left in place for up to one week.

  • Intraspinal injection: Intraspinal opioids are injected into the fluid around the spinal cord. These may be combined with a local anesthetic to help some patients who have pain that is very hard to control.

Common side effects are nausea, sleepiness, and constipation.

Your doctor will discuss the side effects with you before opioid treatment begins and will watch you for side effects. The following are the most common side effects:

Sleepiness and nausea most often occur when opioid treatment is first started and usually get better within a few days.

Opioids slow down the muscle contractions and movement in the stomach and intestines, which can cause hard stools. To keep the stool soft and prevent constipation, it's important to drink plenty of fluids. Unless there are problems such as a blocked bowel or diarrhea, you will be given a treatment plan to follow to prevent constipation and information on how to avoid problems with your intestines while taking opioids.

Other side effects of opioid treatment include the following:

  • Vomiting.
  • Trouble thinking clearly.
  • Problems with breathing.
  • Problems with sexual function.

Talk with your doctor about side effects that bother you or become severe. The doctor may decrease the dose of the opioid, change to a different opioid, or change the way the opioid is given to help decrease the side effects. See the following PDQ summaries for more information about coping with these side effects:

Other drugs may be added to help treat your pain.

Other drugs may be given while you are taking opioids for pain relief. These are drugs that help the opioids work better, treat symptoms, and relieve certain types of pain. The following types of drugs may be used:

There are big differences in how patients respond to these drugs. Side effects are common and should be reported to your doctor.

Bisphosphonates are drugs that are sometimes used when cancer has spread to the bones. They are used to decrease pain and reduce risk of broken bones. However, bisphosphonates sometime cause severe side effects. Talk to your doctor if you have severe muscle or bone pain. Bisphosphonate therapy may need to be stopped.

The use of bisphosphonates is also linked to the risk of bisphosphonate-associated osteonecrosis (BON). See the PDQ summary on Oral Complications of Chemotherapy and Head/Neck Radiation for more information.

The use of cannabinoids given with pain medicine is being studied for cancer-related pain.