Prescription medications

Prescription medications are those prescribed by a doctor in specific doses. They are not available over the counter.

Read through the following pages to learn more about these types of prescription medications for chronic pain:

  • prescription NSAIDs

  • tricyclic antidepressants

  • serotonin and norepinephrine reuptake inhibitors (SNRIs)

  • anticonvulsants

  • corticosteroids

  • muscle relaxants

  • cannabinoids

  • opioids.

Prescription NSAIDs

General points to note

Generally, NSAIDs are best used in short courses to manage flare-ups of pain related to inflammation.

  • NSAIDs available by prescription include diclofenac, meloxicam, and celecoxib.

  • Although there are many types of NSAIDs, only take one type at a time.

  • Because each medication in this group is slightly different, one might work more quickly for you or have different side effects than others.

  • For short flares of pain, a medication that acts quickly and gets out of your system right away might be best. For episodes of pain that last a long time, you may do better with a longer-lasting medication.

  • Before starting any NSAID, tell your doctor if you have a bleeding disorder, asthma or kidney problems or if are undergoing chemotherapy or have ever had a stomach ulcer.

Side effects

  • One of the most common side effects of NSAIDs is stomach upset. Usually, you can avoid this by taking the correct dose and taking the medication with food, even just a glass of milk or some crackers.

  • When used regularly for a long time, or in high doses, NSAIDs can cause kidney problems and stomach ulcers, which can lead to dangerous bleeding and perforations. If you experience blood in bowel movements or severe stomach pain while taking NSAIDs, see your doctor or nurse practitioner right away and stop taking the medication.

  • In very rare cases, NSAIDs can cause bleeding problems. If you are taking NSAIDs, you may need to stop them for a period if you are need to have surgery.

  • If you have migraines, don’t take NSAIDs on more than 15 days of the month, as they can make your headaches worse.

Tricyclic antidepressants (TCAs)

General points to note

  • Tricyclic anti-depressants (TCAs) were first developed to treat depression but they were then found to offer relief for neuropathic (nerve) pain.

  • Much smaller doses of TCAs are given for pain relief than for treating depression.

Side effects

The short-term side effects are usually not troublesome and tend to go away after a few days.

If your doctor thinks that TCAs might be helpful, they may recommend that you have an electrocardiogram or ECG before you start them. This test measures the electrical activity of your heart, or your heart rhythm, to check that it is regular and that it is safe to start the medications.

Serotonin and norepinephrine reuptake inhibitors (SNRIs)

General points to note

  • SNRIs were originally developed to treat depression and anxiety, but scientists have found that they are also helpful for pain.

  • SNRIs work by helping to slow down communication of pain signals between nerves.

  • If you also suffer from depression or anxiety, it can be helpful to take one medication that treats both problems rather than two different medications.

  • These medications are not recommended for people with liver problems.


General points to note

  • Anticonvulsants were first developed to treat seizures but also treat nerve related pain because they have a calming effect on overactive pain nerves.

  • Some commonly prescribed anticonvulsants include gabapentin, pregabalin or topiramate.


General points to note

  • Corticosteroids (steroids) reduce pain by reducing inflammation. They can be given by injection at the site of pain. Often, the steroid is given as a mixture with local anesthetic. The local anesthetic blocks pain messages along the nerves; this works very quickly and lasts for a few hours. The steroid often takes a week or so to have full effect. Corticosteroids can also be given by mouth or be applied as a prescribed topical cream.

  • Corticosteroids can cause side effects if taken by mouth for a long time, but as a single injection or taken orally for a brief period they are unlikely to do so.

  • Corticosteroids work best to treat severe pain associated with nerve irritation and inflammation.

Muscle relaxants

General points to note

  • Muscle relaxants cause tense muscles to relax and prevent muscle spasms, so easing pain.

  • Commonly used muscle relaxants are methocarbamol and baclofen. You can buy some of these medications over the counter, but others require a prescription.

  • Often, these medications work well in the short term but lose their effect after as little as two weeks.

  • Long-term use of muscle relaxants carries certain risks, such as addiction, so check with your healthcare team whether these medications are right for you.


General points to note

  • A cannabinoid is a chemical in the cannabis plant (also called marijuana).

  • Natural cannabinoids (herbal cannabis) are extracted and dried from the plant and are smoked or vapourized.

  • It is legal for doctors in Canada to prescribe herbal cannabis for very ill people. However, it is not recommended for anyone under the age of 25 because of its harmful long-term effects on memory, thinking and judgment.

  • Man-made cannabinoids, also called pharmaceutical cannabinoids, are available in a pill or as a mouth spray only by prescription.

  • Pharmaceutical cannabinoids treat nausea, loss of appetite, pain, and muscle spasm in patients with multiple sclerosis and cancer pain. Medical literature supports their use for these medical conditions.

  • Cannabinoids are very powerful medications and must be used very carefully under medical supervision.


General points to note

  • Opioids are among the oldest, strongest, and best-known pain medications.

  • There are many types and strengths of opioids – morphine is a common example - but they are all chemically related to the same poppy plant that produces opium.

  • Your pain care team will only decide to start you on opioids after discussing their risks and benefits fully. They are not a first resort treatment and it is unclear how effective or safe they are for chronic pain.

  • As with any medication, opioids are given on a trial basis, for example for three months. At the end of the trial, you and your pain management team would assess if your pain and function have improved enough to justify continuing the medication.

Side effects

Common side effects

  • Laxatives can be prescribed to ease constipation (listed above), but it does not tend to clear up over time.

  • Because opioids cause drowsiness, do not drive until you know how they might affect you.

Less common but potentially serious side effects

  • The potentially serious side effects are listed in the table. Other side effects relate to the dose of the medication.

  • Your doctor or nurse practitioner can monitor the levels of your sex hormones through a physical exam.

  • In high doses, opioids can sometimes make your pain worse instead of better.

  • Uncommonly, and if given in too high a dose, opioids can cause low blood pressure or slow and shallow breathing. People need to be carefully monitored for these negative side effects.

  • Tell your healthcare team if you have a breathing-related disease so you can minimize the risks associated with the breathing side effects of opioids.

  • Healthcare professionals can provide guidance that will help you to manage these negative side effects.

Managing the risks of opioids

If opioids are prescribed for your treatment, the amount will depend on your weight and how much is needed for effective pain management. Anyone prescribed an opioid will also need to complete an ‘Agreement for Opioid Therapy’ form to help ensure the safety of using opioid therapy. Your health will be monitored regularly, which may include urine testing to make sure that you are using your opioids as prescribed. If the prescription is interrupted for any reason and then restarted at the original dose, your body might lose its tolerance and result in overdose.

Even if you take opioids exactly as prescribed and without any of the side effects listed above, opioid use can have the following risks:

  • addiction

  • physical dependence

  • tolerance

  • overdose


Drug addiction is a psychological craving as well as physical dependence on the drug. People who are addicted to opioids feel unable to stop the medication even after it starts to cause them harm.

When doctors prescribe opioids for pain, they closely control the amount and pattern of use so that they can identify early on if problems are developing.

You may be more at risk of developing an addiction if

  • your prescription includes daily use

  • you, your parent or your sibling has had an addiction to any substance

  • you experienced early life trauma (neglect, emotional, physical or sexual abuse)

  • you are taking a fast-acting opioid (one that releases medication into your bloodstream quickly).

Please speak to your healthcare team if you or any family members are concerned about your risk of becoming addicted or have identified possible signs of addiction such as excessive craving or misuse of the medications.

Physical dependence

Physical dependence means that your body has become used to the effects of a drug. On its own, it is not the same as addiction.

Physical dependence can occur in as little as five days if you are taking opioids continuously. You will usually know the signs of physical dependence only if you suddenly stop the medication. These include uncomfortable 'withdrawal' symptoms such as feeling irritable, shivery and nauseated and having stomach pain.

You and your healthcare team can prevent withdrawal by planning to reduce your dose little by little if your need for pain relief reduces or if the medication is not working for you.


Tolerance happens when your body needs a higher dose of a drug to get the same effect. It commonly happens when people are treated with opioids for a long time. If tolerance occurs, your healthcare team might decide to switch you to a different opioid medication.


Many people who take strong opioid medications have concerns about overdose. An overdose means taking so much medication that it causes your thinking and breathing to slow down. Overdoses can be very dangerous, even deadly.

The risk of overdose is quite low when opioids are taken over the long term. They have been used for centuries and healthcare professionals know how to prescribe them with a great degree of safety. That said, the following factors can make an overdose more likely to happen:

  • starting or increasing an opioid dose

  • interrupting and restarting an opioid prescription

  • taking an opioid with benzodiazepine (a medication to treat mood and sleep disorders) or other sedating medications (for example Gravol, Benadryl, antidepressants, gabapentin)

  • kidney disease

  • liver disease

  • sleep disorders, including sleep apnea.

To prevent the risk of overdosing:

  • talk to your healthcare team about your risk factors

  • take the medications exactly as prescribed by your healthcare team

  • monitor your medications frequently with your healthcare team

  • talk to your healthcare team about all the other medications, supplements, alcohol or other drugs that you may be taking in case there are any bad drug interactions.

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