What Are the Side Effects of Pain Medicines and How Are They Managed?

The side effects of opioids are easily managed. When first starting to take these medicines, some patients may become drowsy and others may develop some nausea. Vomiting is not common. For most patients, these side effects can be easily managed and usually disappear within 1-3 days. Many different anti-nausea medicines are available today to lessen and control any nausea or vomiting that might occur. To lessen drowsiness, opioids are started at low doses and adjusted or titrated (a gradual change in dose to reach the point of maximum pain relief with the minimum side effects). In older patients, the starting dose is usually lowered.

Opioids cause constipation to some degree in most people. Constipation usually occurs after several days of taking opioids and can continue the entire time the medicine is taken. Constipation can be quite painful and may require hospitalization; therefore, it is important to prevent it, if possible. Constipation can usually be prevented and/or controlled by the following measures:

• Increase intake of liquids,
• Increase dietary fiber, adding such foods as fruits, vegetables, and bran,
• Exercise after planning your activities with your doctor or physical therapist.
• Use medicines, such as laxatives and stool softeners, as discussed with the doctor or nurse.

If constipation develops, call your doctor or nurse to discuss additional measures.

Some people mistakenly think they are allergic to opioids if they become nauseated. Nausea alone usually is not an allergic response. But nausea with a rash or itching may be an allergic reaction. If this occurs, patients should stop taking the medicine and tell their doctor at once. Itching, although rare, may occur at first and can be treated with diphenhydramine (Benadryl®). If sleepiness is a problem after the first few days, talk with your doctor about ways to reduce it.

Families are often concerned about a slowing of breathing that they associate with a hastening of death. Opioids can slow down breathing, but it does not mean that death is near.

Rarely, patients may experience confusion or “fuzzy thinking,” which can be persistent. This can continue to a change in mental function and disorientation, which means that patients do not know where they are or what day of the week it is. The mind wanders and speech is not understandable. These symptoms are called delirium, and the cause is not clearly understood. It may be necessary to switch to another medicine or reduce the dose of the current drug and add an adjuvant analgesic. Always report any change in mental status to the cancer care team.

Medicine Tolerance

People who take opioids for pain sometimes find that over time they need to take larger doses. This may be because the pain has increased or because they have developed medicine tolerance, also called drug tolerance. Medicine tolerance occurs when the body gets used to the medicine being taken; the medicine does not relieve the pain as well as it once did. Many people do not develop a tolerance to opioids. If tolerance does develop, usually small increases in the dose or a change in the kind of medicine will help relieve the pain.

People sometimes confuse tolerance with addiction. The two are very different. Tolerance can occur over time, indicating that the body requires more medicine to achieve the same level of comfort. A need to increase the dose of medicine is not a sign of addiction.

Stopping an Opioid Medicine

Stopping opioids suddenly sometimes causes symptoms, including a flu-like illness, excessive perspiration, or diarrhea. Opioids are stopped gradually to reduce the chances of any noticeable symptoms occurring. If symptoms do occur, they can be treated and tend to disappear in a few days to a few weeks. The doctor will discuss with the patient the best way to stop taking these medicines.

How Are Pain Medicines Given?

Dosing

Among patients there are enormous differences in the amount (dose) of medicine needed to relieve pain, even among patients with similar types of pain. The goal of pain medicine therapy is to provide the maximum benefit to the patient with the least amount of medicine and with the fewest side effects possible. In general, the starting dose will be low, and the amount will be increased until the pain is adequately relieved. This dose adjustment is called titration, that is, adjusting the dose to achieve acceptable pain control. Titration refers to increasing or decreasing the medicine dose. Doctors carefully adjust the doses of pain medicines so there is little possibility of taking too much.

Administering Medicines

Some people think that if their pain becomes severe, they will need to receive intramuscular (IM) injections or “shots.” Actually, injections are not commonly used to relieve cancer pain. Giving medicines by mouth (oral administration) is recommended for most patients because it is convenient, well tolerated, and usually is the least expensive. In addition to pills or capsules, there are other ways the medicine can be given:

• Skin patch. A bandage-like patch is placed on the skin that slowly but continuously releases the medicine through the skin for 2-3 days. One opioid medicine, fentanyl, is available as a skin patch. Giving medicine in this way is less likely to cause nausea and vomiting.
• Rectal suppositories. This type of medicine dissolves in the rectum and is absorbed by the body.
• Injections. Medicines can be given under the skin using a small needle as a subcutaneous (SQ) injection; or into the muscle through a needle as an intramuscular (IM) injection, although these are not recommended when repeated injections are needed; as an intravenous (IV) injection, or directly into the vein through a needle or thin plastic catheter; as an intrathecal (IT) injection, giving medicine directly into the fluid around the spinal cord; or as an epidural injection, giving the medicine into the space between the spinal canal and bones of the back. When the intrathecal or epidural routes are used, opioids may be delivered continuously from a small pump. In situations in which this method will be used over a long period of time, the pump can be placed under the skin.
• Patient-controlled analgesia (PCA). When pain relief is needed, the patient can receive a preset dose of pain medicine by pressing a button on a computerized pump that is connected to a small tube in the body. The medicine is injected into the vein (intravenously), just under the skin (subcutaneously), or into the spinal area.

The way the medicine is given is influenced by several factors, such as patients having difficulty taking pills, the presence of irritating side effects, or pain that is not controlled with an opioid given by mouth. Patients who are having difficulty taking their medicines should ask their doctor about a different method of administration.

Scheduling

When the pain occurs day after day, medicines are given on an around-the-clock (ATC) schedule to ensure that the body always has a supply. In the past, medicines were given only on an as needed basis, or PRN, with the patient waiting until they were in pain. This type of schedule allowed periods of severe pain. Around-the-clock dosing works better. This means giving the medicine on a regular basis, whether the patient is in pain or not. In some situations patients are instructed to take a pain medicine as needed. This is usually along with an ATC medicine that they are already taking.

Psychosocial Support for the Person With Cancer Pain

Support for Adequate Pain Management

• Psychosocial support is an important part of effective pain control.
• Effective pain control improves the patient’s quality of life.
• Pain can be managed by the primary health care team.
• Pharmacy and pharmaceutical companies should be contacted for financial support if payment is a problem for the patient.
• Families may have to speak up and ask for pain management and symptom control if the patient is not able to.

Emotional Support

• Emotional responses to pain are normal.
• Emotional support from the cancer team shows the patient that pain is a problem to be addressed.
• The cancer care team will work with the patient and family to address the pain problem.
• A plan of action will be developed, including when results can be expected.
• The cancer care team is committed to relieving the patient’s pain.
• There is always something else that can be done to try to manage the patient’s pain or other bothersome symptoms.

Skills Needed

• Coping skills to help manage emotional responses, provide pain relief, and enhance a sense of personal control.
• Coping skills such as breathing exercises and distraction techniques for pain emergency.
• Coping skills for chronic pain, which includes the above plus relaxation techniques, guided imagery, and hypnosis.

Are There Clinical Trials Studying New Pain Treatments?

All drugs used to treat pain, cancer, or other diseases must undergo clinical trials in order to determine their safety and effectiveness before the Food and Drug Administration (FDA) can approve them for use.

When studying promising new or experimental treatments, researchers want to know:

• Does this new type of treatment work better than other treatments already available?
• What side effects does the treatment cause?
• Do the benefits outweigh the risks, including side effects?
• Which patients will the treatment most likely help?

During cancer treatment, the doctor may suggest taking part in a clinical trial of a new treatment for pain. Scientists conduct clinical trials only when they believe that the treatment being studied may be better than other treatments.

The purpose of the study is to find out if the new treatment will work better than the standard treatment and if the side effects are worse or less. The new therapy may have some side effects, which the doctor will discuss with the patient before the clinical trial is started.

Taking part in any clinical trial is completely voluntary. Doctors and nurses explain the study in detail and provide a consent form to read and sign. This form states that the patient understands the risks and wants to participate. Even after signing the form and the trial begins, the patient may leave the study at any time, for any reason.

Taking part in the study will not keep anyone from getting other medical care they may need. Patients should always check with their health insurance company to find out whether it will cover the costs of taking part in a clinical trial.

Participating in a clinical trial evaluating new, improved methods for managing cancer pain may help the patient directly, and it may help other people with cancer pain in the future. For these reasons, members of the National Comprehensive Cancer Network and the American Cancer Society encourage participation in clinical trials.

PAIN TREATMENT

For more information on these treatment guidelines, or on cancer in general, call the NCCN at 1-888-909-NCCN or the American Cancer Society at 1-800-ACS-2345. Or you can visit these organizations’ web sites at www.cancer.org (ACS) and www.nccn.org (NCCN).

© 2005 by the National Comprehensive Cancer Network (NCCN) and the American Cancer Society (ACS). All rights reserved. The information herein may not be reproduced in any form for commercial purposes or downloaded and stored in any information-retrieval system without the express written permission of the NCCN and the ACS. Single copies of each page may be printed out for personal, noncommercial use only.