Types of pain drugs
Non-opioids, opioids and adjuvant analgesics are the 3 main types of drugs used to manage pain related to cancer. These drugs help control pain in different ways. They may be used by themselves or they may be given in combination. It is important to take pain medicines as directed, even if they do not seem to help with the pain right away. It can take some time, sometimes up to weeks, for these drugs to be effective.
Non-opioid drugs are used alone to treat mild to moderate pain. They may be given in combination with opioid drugs to relieve moderate to severe pain. These drugs can be short-acting (immediate release) or long-acting (sustained or controlled release). Most non-opioid drugs are over-the-counter medicines, so you don’t need a prescription.
Acetaminophen (Tylenol, Atasol) is a non-opioid drug commonly used to control mild pain and reduce fever. Your doctor may not want you to take acetaminophen regularly if you’re getting chemotherapy because it can cover up a fever.
Most of the time, there are no side effects from a normal dose of acetaminophen. Taking large doses every day for a long time can damage the liver.
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Nonsteroidal anti-inflammatory drugs (NSAIDs) help control pain and reduce inflammation or swelling. They can help manage pain related to cancer that affects bones or soft tissues.
Some NSAIDs can be bought as over-the-counter drugs, including ibuprofen (Motrin, Advil, Nuprin) and acetylsalicylic acid (ASA, Aspirin, salicylate). Other NSAIDs are available only with a prescription, including diclofenac cream (Voltaren), indomethacin (Indocin, Indocid) and celecoxib (Celebrex).
Some NSAIDs can upset or cause bleeding in the stomach. Taking NSAIDs with some food or just after a meal can lower the risk of stomach problems. NSAIDs can also stop blood from clotting the way it should. You should not take NSAIDS if you are receiving chemotherapy or about to have surgery. Children and teens should not take aspirin or products that contain it. NSAIDs can also cause kidney problems, especially for someone who is dehydrated or already has kidney problems. Some people can’t take NSAIDs because of these side effects.
NSAIDs can interact with other medicines. Talk to the healthcare team to make sure it is safe to take NSAIDs. The healthcare team can also give information about what type and strength of drug might work best.
Corticosteroid drugs are only available by prescription. These drugs have more powerful anti-inflammatory properties than NSAIDs. Examples of corticosteroids include prednisone (Deltasone) and dexamethasone (Decadron, Dexasone).
Corticosteroid drugs may help reduce swelling and relieve pain, especially pain from a tumour that presses on or has damaged a nerve. Corticosteroids may also increase appetite and reduce nausea to make a person feel better.
Side effects of corticosteroids can include:
- upset stomach
- trouble sleeping
- fluid retention
- weight gain
- increased risk of infection
- bleeding from the stomach or intestine (the long, tube-shaped organ that goes from the stomach to the anus)
- muscle weakness
Do not stop taking corticosteroids suddenly. When it is time for you to stop taking these drugs, the healthcare team will slowly reduce the dose to wean you off them.
Opioids are also called narcotics. They are used to control moderate to severe pain and are the type of drug used most often to control pain related to cancer. These drugs can be short-acting (immediate release) or long-acting (sustained or controlled release). Opioid drugs may be given alone or with other opioids to relieve pain.
Common opioid drugs
Most opioid drugs are only available with a prescription. Common opioids include:
- oxycodone (OxyContin)
- hydromorphone (Dilaudid)
- morphine (MS Contin, Statex, MOS)
- fentanyl (Duragesic)
Opioids and non-opioids are sometimes combined to control pain. Some common combinations include:
- codeine and acetaminophen (Tylenol 1, Tylenol 2, Tylenol 3)
- codeine and acetylsalicylic acid (ASA, Aspirin, salicylate)
- oxycodone and acetaminophen (Percocet)
- oxycodone and acetylsalicylic acid (Percodan)
Side effects of opioids
Everyone will have some side effects from opioid medicines, but they are usually mild and easy to manage. Talk to the doctor if you need help to deal with any of the common side effects of opioids listed below.
Constipation caused by opioids will not go away on its own, even when the body is used to the drug. This is because opioids slow down the passage of stool through the intestinal tract. The stool becomes hard as more liquid is absorbed from it, which can make it hard to have a bowel movement. Some people may not have as much of an urge to go to the bathroom.
The best way to prevent constipation is to be physically active and increase fluid and fibre intake. The healthcare team may suggest a laxative, stool softener or suppository to relieve constipation.
Opioids can lower the amount of saliva the body makes, which can cause dry mouth. Sucking on ice chips or sour lemon candies and drinking lots of fluids can help to relieve a dry mouth. The healthcare team may recommend artificial saliva sprays to help relieve dry mouth.
Nausea and vomiting
Opioids can cause nausea and vomiting or an upset stomach during the first week. In most cases, the nausea goes away over time. Resting quietly for a little while after taking the opioid may help. Relaxation, imagery and deep breathing can also help with nausea. The healthcare team may suggest taking an antinausea medicine.
Opioids can make you feel sleepy when they are first taken or when the dose of an opioid is increased. This feeling often passes within a few days. Drowsiness can also be caused by the body needing to catch up on rest now that the pain is under control. Opioids affect everyone differently. Talk to the healthcare team if pain medicine is still causing drowsiness after taking it for 3 days.
Changes in mental alertness
Opioids can cause changes in mental alertness at first. After taking the same dose of a medicine for a few days, this should improve. Talk to the healthcare team if there are still problems with mental alertness or carrying on normal activities after a few days. Changing the dose or taking a different type of opioid can often help manage this side effect. There may be certain activities, such as driving or using power tools, that should be avoided when taking opioids. Talk to the healthcare team about what activities are safe when taking opioids.
Everyone reacts differently to different opioids. Sometimes opioids can cause twitching or jerking in the muscles, especially when falling asleep. This could just be how the body reacts to the medicine. Muscle jerks can also occur with higher doses of opioids.
Opioids may cause itching. This side effect may occur all over the body, but it usually only affects the face, neck and upper chest. Using antihistamines, taking oatmeal baths and keeping the skin clean and dry can help ease itching.
Opioids may cause urinary retention, which is difficulty emptying the bladder. The dose of the opioid may need to be lowered, if possible. Sometimes a catheter may be needed to help empty the bladder.
Lowered breath rate
Some opioid drugs can cause respiratory depression, which is a decrease in the number of breaths and the ability to take deep breaths. It is one of the most serious possible side effects of opioids. The healthcare team will check vital signs often when opioids are first given. Oxygen may be given if respiratory depression occurs.
Other types of medicine may be given along with non-opioid and opioid drugs to help control pain. These medicines are called adjuvant analgesics. They may not be specifically designed to relieve pain, but they may be given to help manage it.
Bisphosphonates are drugs that help protect and prevent the breakdown of bone. They may be used to relieve pain caused by cancer that has spread to the bone. It may take days or weeks for bisphosphonates to relieve pain.
Some bisphosphonates used to treat pain related to cancer include:
- clodronate (Bonefos)
- pamidronate (Aredia)
- zoledronic acid (Zometa, Aclasta)
Bisphosphonates are only available with a prescription. They are often given in a treatment centre by intravenous infusion, which gives medicines over time through a needle in a vein. Some bisphosphonates may be taken by mouth.
Side effects of bisphosphonates can include:
- pain at the injection site
- increased bone pain (bone pain may become worse when bisphosphonates are first given, but this is usually temporary)
- change in kidney function
- low calcium levels
- death of the jaw bone (osteonecrosis)
If taking bisphosphonates, it is important to let the dentist know before any dental surgery involving the bone.
Antiseizure (anticonvulsant) medicines may be used to treat nerve pain. They work by reducing the pain signals from damaged nerves. Antiseizure medicines are only available with a prescription. They are usually taken by mouth.
Some antiseizure drugs used to relieve pain related to cancer include:
- carbamazepine (Tegretol)
- gabapentin (Neurontin)
- phenytoin (Dilantin)
Side effects of antiseizure drugs can include:
- weight gain
- swelling of the arms and legs
- shaking or uncontrolled muscle movements
Taking an antidepressant doesn’t always mean that the person taking it is depressed. Some antidepressant medicines can help relieve nerve pain. Antidepressants are only available with a prescription. They are usually taken by mouth.
Antidepressants that may be used to treat pain related to cancer include:
- amitriptyline (Elavil)
- nortriptyline (Aventyl)
- desipramine (Norpramin, Pertofrane)
- selective serotonin reuptake inhibitors (SSRIs)
Side effects of antidepressants can include:
- dry mouth
- weight gain
Sometimes severe pain can cause muscles in the body to tighten and spasm. Muscle relaxants may be given if muscle spasms cause pain or make pain worse. These drugs are usually taken by mouth.
Some muscle relaxants, such as baclofen (Lioresal), are available over the counter. Others, like cyclobenzaprine (Flexeril), are only available with a prescription. Some anti-anxiety drugs, including diazepam (Valium) or lorazepam (Ativan), may also be used to relieve muscle spasms in people who have severe pain. The healthcare team can suggest types and strengths of muscle relaxants that may help relieve pain and reduce muscle spasms.
Side effects of muscle relaxants can include: