Guide to Controlling Cancer Pain

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Common questions about taking pain medicines

How is pain medicine given?

Some people think that if their pain becomes severe, they will need to get injections or “shots” of pain medicine. In fact, shots are rarely given to relieve cancer pain. There are many other ways you can take pain medicine.

Oral – means the drug is taken by mouth, either by being swallowed or melted in the mouth. Medicine is given as a liquid, pill, capsule, or in transmucosal form (the drug is in a lozenge or “sucker” and absorbs directly through the tissues of the mouth).

Skin patch – a clear, bandage-like patch placed on the skin. It slowly but constantly releases medicine through the skin for 2 to 3 days. This form of medicine is less likely to cause nausea and vomiting.

Rectal suppositories – medicine that dissolves in the rectum and is absorbed by the body


  • Subcutaneous (SC) injection – medicine is put just under the skin using a small needle.
  • Intravenous (IV) injection – medicine goes right into a vein through a needle, port, or catheter.
  • Intrathecal and epidural injections – medicine is put into the fluid around the spinal cord (intrathecal) or into the space around the spinal cord (epidural).

Pump, or patient-controlled analgesia (PCA) – with this method, you have control over the amount of pain medicine you take. When you need pain relief, you press a button to get a pre-set dose of pain medicine through a computerized pump. (The pump carefully controls how much you can get at a time, so you cannot take too much.) The pump is connected to a small tube going into your body. The medicine goes into a vein (intravenously), just under the skin (subcutaneously), or into the area around the spine.

What are the side effects of pain medicine?

Each type of pain medicine has its own side effects, even those that you can buy over the counter. Some, such as aspirin or ibuprofen (and others in that family of drugs), can cause stomach irritation, or even bleeding, and should be taken with food. Side effects are listed in more detail for each group of drugs in Table 1.

Many side effects from opioid pain medicine can be prevented. Constipation, for instance, is easier to prevent than treat. Most doctors will start you on a plan to prevent constipation at the same time they start your opioid pain medicines. Some mild opioid side effects such as nausea, itching, or drowsiness, often go away without further treatment after a few days, as your body adjusts to the medicine. Let your doctor or nurse know if you’re having any side effects and ask for help in managing them.

More serious side effects of pain medicine are rare. As with the more common ones, they often happen in the first few hours of treatment. They include trouble breathing, dizziness, and rashes. If you have any of these side effects, call your doctor right away.

If you take any medicines to calm you down (sedatives or tranquilizers), use alcohol, or take sleeping pills, you raise your risk of serious side effects from opioids. People have died from combining these substances with opioids. Talk to your doctor about them before you start taking opioids for pain.

Keep in mind that you usually cannot take aspirin, ibuprofen, and other NSAIDs when you are getting chemotherapy. If you are getting cancer treatment, talk to your doctor before you take any non-prescription pain relievers.

Will taking 2 different opioid pain medicines cause more side effects?

This is usually not a problem. In fact, long-acting and short-acting drugs are used together so that you have fewer side effects. Most people only have breakthrough pain a few times a day and the breakthrough pain is usually much more severe than their chronic pain. By taking a short-acting medicine for breakthrough pain, you get extra medicine only when you need it. Most of the time you can expect the same types of side effects from breakthrough pain medicines as from long-acting medicines.

Which medicines will I be given?

In many cases, non-opioids are all you’ll need to relieve your pain, especially if you “stay on top of the pain” by taking them regularly. These medicines are stronger pain relievers than most people realize. For example, certain doses of opioids given by mouth are no more effective than 2 or 3 regular tablets of aspirin, acetaminophen, or ibuprofen.

If you do not get pain relief from non-opioids, opioids will usually give you the relief you need. Most side effects from opioids can be prevented or controlled. You should talk to your doctor, nurse, or pharmacist about taking opioids along with non-opioids. The 2 types of medicine relieve pain in different ways and have different side effects. Aspirin, acetaminophen, or ibuprofen taken 4 times a day might help you reduce or even avoid the need for stronger pain relievers. And many people who take opioids can get more relief if they keep taking regular doses of these milder pain medicines.

Some pain medicines combine an opioid and a non-opioid, like aspirin or acetaminophen, in the same pill. Ask your doctor, nurse, or pharmacist how much aspirin or acetaminophen, if any, is in your prescription. They can help you figure out how much of these medicines you can take together safely. Other classes of medicines, such as antidepressants and anti-convulsants, may also be needed to relieve certain types of cancer pain.

Last Medical Review: 06/10/2014
Last Revised: 06/10/2014