How Adjuvant Analgesics Are Used to Treat Chronic Pain

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An adjuvant analgesic, or coanalgesic, is a medication that is not primarily designed to control pain but can be used for this purpose. Some examples of adjuvant drugs are antidepressants (which are typically used for mental health conditions) and anticonvulsants (used in the treatment of seizure disorders). You might be prescribed an adjuvant analgesic in addition to other pain medications or on its own.

Adjuvant analgesics tend to be less effective for musculoskeletal pain, such as back pain or joint pain. However, they can work well for neuropathic pain and pain syndromes such as fibromyalgia. They also have a role in treating cancer pain.

Unlike many other non-opioid analgesics, adjuvant analgesics are not available over the counter.

Depending on the kind of pain you have, you may be able to choose from several different types of adjuvant analgesics. The ideal combination of medications varies greatly from one person to the next, even among people with the same condition.

Antidepressants

While antidepressants are not often thought of as pain medication, some can effectively treat chronic pain conditions.

Antidepressants are thought to control the way pain messages are sent and processed between the spinal cord and the brain. In addition, these drugs may decrease anxiety (which is common in some pain conditions) and help regulate sleep. Better sleep can, in turn, help lower pain levels.

ANTIDEPRESSANTS FOR CHRONIC PAIN
Condition Tricyclics SSRIs/SNRIs Atypical
Arthritis X X X  
Neuropathy  X

X

X
Postherpetic neuralgia
(nerve damage from shingles)
X

 

 
Fibromyalgia X X X
Chronic fatigue syndrome (ME/CFS) X X  
Irritable bowel syndrome (IBS) X X  
Migraine X    
Complex regional pain syndrome (CRPS) X    

Tricyclic antidepressants (TCAs) can include:

Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) can include:

Some atypical antidepressants are also commonly used to treat both chronic pain syndromes and nerve pain, such as:

Monoamine oxidase inhibitors (MAOIs) are not often prescribed for chronic pain because newer drugs are considered safer, have fewer dangerous drug interactions, and don't require a restricted diet like MAOIs do.

Anticonvulsants

Anticonvulsants can also be used to treat chronic pain. Anticonvulsants work by not allowing certain types of nerve transmissions. They can also decrease neuropathic pain, such as that caused by trigeminal neuralgia, diabetic neuropathy, CRPS, and fibromyalgia (which may involve small-fiber neuropathy and other types of nerve pain).

Anticonvulsants commonly used to manage chronic pain include:

Corticosteroids

Oral corticosteroids, also called glucocorticoids, lower pain by inhibiting some mechanisms of inflammation and reducing blood flow to alleviate edema (fluid retention). They can also reduce neuropathic pain by lessening signals from injured nerve. These drugs are also commonly used for treating CRPS and cancer pain.

Side effects are more likely with long-term use, so corticosteroids are generally recommended for short-term treatment. When they are used for long-term therapy, doctors should monitor patients closely.

Corticosteroids are also available via injection and for topical use.

Common corticosteroids are:

Antispasmodics

This class of drugs is also known as muscle relaxants. They come in two forms: one to treat smooth muscles (such as those in the gastrointestinal tract) and another to treat skeletal muscle spasms.

Antispasmodics for smooth muscles are most often used for treating the intestinal spasms of IBS but they can also be effective against stomach or bladder spasticity.

Smooth-muscle relaxants include:

A growing body of research suggests that the long-time traditional remedy peppermint oil may have antispasmotic properties that can be beneficial for people with IBS—and that it may possibly be even better than antispasmotic drugs. The American College of Gastroenterology even recommends it as a first-line treatment.

Skeletal muscle antispasmotics are a common choice for musculoskeletal conditions, especially if physical therapy hasn't been successful. Drugs in this class may also be used to treat spasms associated with neurological conditions, such as:

Common musculoskeletal antispasmotics include:

The antispasmotic/antineuralgic drug Lioresal (baclofen) is sometimes used to treat a condition called trigeminal neuralgia that causes facial pain.

Topical Agents

Topical agents are popular adjuvant choices for neuropathic pain, arthritis, fibromyalgia, CRPS, and other conditions that cause muscle or nerve pain. They're also used for injuries such as sprains.

These medications are applied directly to the skin and absorbed into the bloodstream. They may be available as creams, ointments, or patches. Both over-the-counter and prescription forms are available.

Lidoderm (lidocaine) is a local anesthetic that works by preventing nerves from sending pain signals to your brain.

Capsaicin cream, which is made from the "hot" component of chili peppers, is a counter-irritant. Essentially, topicals containing capsaicin stimulate nerve endings when you put them on your skin, and those signals interfere with your body's pain signals.

Mentholated products, which may make your skin feel hot, cold, or a combination of the two, are counterirritants. Simply put, they purposefully irritate the skin as a means of distracting your brain from focussing on your pain.

Common brand names include:

Other Adjuvants

Some drugs have more limited uses as adjuvant painkillers, but may be considered.

Bisphosphonates

Bisphosphonates are used for pain from CRPS and cancer that has spread to the bone. Originally used to counter bone loss, they've also been found to have a direct impact on these types of pain.

Common bisphosphonates include high-dose Fosamax (alendronate) and the intravenous drug Aredia (pamidronate).

NMDA Receptor Antagonists

N-mthyl-D-aspartate (NMDA) receptor antagonists are injectable anesthetics that can help alleviate pain from cancer (especially in cases where morphine is not longer effective), CRPS, and in emergency settings.

Examples of these drugs are ketamine and dextramethorphan (a liquid form of which is used as a cough syrup).

Botox

Botulinum toxin (Botox) injections can be used to treat muscle stiffness, spasticity, some types of neuropathic pain, post-stroke pain, and CRPS.

A Word From Verywell

If your pain isn't well managed by first-line treatments, talk to your doctor about what adjuvant analgesics might help you get your pain under control. With such a wide variety of drugs to consider, you shouldn't have to settle for inadequate pain treatment and the reduced quality of life that comes with it.

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  5. Alammar N, Wang L, Saberi B, et al. The impact of peppermint oil on the irritable bowel syndrome: a meta-analysis of the pooled clinical dataBMC Complement Altern Med. 2019;19(1):21. doi:10.1186/s12906-018-2409-0

  6. Ford AC, Moayyedi P, Chey WD, et al. American College of Gastroenterology monograph on management of irritable bowel syndromeAmerican Journal of Gastroenterology. 2018;113:1-18. doi:10.1038/s41395-018-0084-x.

  7. Park J, Park HJ. Botulinum toxin for the treatment of neuropathic painToxins (Basel). 2017;9(9):260. Published 2017 Aug 24. doi:10.3390/toxins9090260

Additional Reading
  • Lussier D, Portenoy RK: Adjuvant Analgesics. In Doyle D, Hanks G, Cherny NI, Calman K (eds): Oxford Textbook of Palliative Medicine. Oxford: Oxford University Press, 4th Ed, Oxford: Oxford University Press, 2011.

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