How Adjuvant Analgesics Are Used to Treat Chronic Pain

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An adjuvant analgesic is a medication that is not primarily designed to control pain but can be used for this purpose. Some examples of adjuvant drugs are medications like antidepressants and anticonvulsants. They may also be called coanalgesics.

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.

Types of Adjuvant Analgesics

There are several different types of adjuvant analgesics, depending on the type of pain you're trying to treat.

Antidepressants

While antidepressants are not often thought of as pain medication, they can effectively treat chronic pain conditions. Antidepressants are thought to control the way pain is perceived from the spinal cord to the brain. In addition, antidepressants may decrease anxiety and help regulate sleep.

However, not all types of antidepressants are effective in managing chronic pain. Tricyclic antidepressants (TCAs) such as amitriptyline, selective serotonin reuptake inhibitors (SSRIs), like duloxetine, and others, such as nefazodone, are commonly used to treat both chronic pain syndromes and nerve pain. Monoamine oxidase inhibitors (MAOIs) are not as effective in chronic pain control.

Anticonvulsants

Anticonvulsants, which are medications most commonly used to control seizure disorders, can also be used to treat chronic pain. Anticonvulsants work by not allowing certain types of nerve transmissions, and they can decrease neuropathic pain, such as those caused by trigeminal neuralgia or diabetic neuropathy. Anticonvulsants commonly used to manage chronic pain include gabapentin and pregabalin.

Gabapentin is the most widely-used adjuvant analgesic. Some patients who don't respond well to gabapentin respond instead to pregabalin, and vice versa.

Adjuvants Used for Multiple Types of Pain Syndromes

Corticosteroids:

Tricyclic antidepressants:

  • Amitriptyline: Not recommended for the elderly or patients with a heart disorder.
  • Desipramine

Selective serotonin and norepinephrine reuptake inhibitor (SNRI) antidepressants:

  • Duloxetine: Better tolerated than tricyclic antidepressants.
  • Milnacipran

Alpha-2-adrenergic agonists:

  • Tizanidine

Topical agents such as capsaicin can be used for neuropathic pain and arthritis. Local anesthetics such as a lidocaine patch may also be used.

Adjuvants Used for Neuropathic Pain

A variety of different types of drugs may be used for neuropathic pain.

Anticonvulsant agents:

  • Gabapentin: The preferred drug of the anticonvulsants.
  • Pregabalin
  • Carbamazepine: The first-line treatment for trigeminal neuralgia.
  • Phenytoin: Considered to be a second-line drug.

Antidepressant agents:

  • Elavil (amitriptyline)
  • Cymbalta (duloxetine)
  • Venlafaxine

Antispasmodics:

  • Lioresal (baclofen): Used in trigeminal neuralgia.
  • Cyclobenzaprine
  • Zanaflex (tizandine)

Topical agents:

  • Lidocaine 5% patch
  • Capsaicin 0.025% and 0.075%

Adjuvants Used for Complex Regional Pain Syndrome

  • Bisphosphonates (e.g., pamidronate)
  • Clonidine
  • Dextromethorphan
  • Lidocaine creams and patches
  • Ketamine
  • Prednisolone
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)

A Word From Verywell

If you wonder why different medications are being used to treat your chronic pain, ask your doctor or pharmacist to explain. They should be able to help you understand the biochemistry involved in your pain management and help you find relief.

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  1. Khan MI, Walsh D, Brito-dellan N. Opioid and adjuvant analgesics: compared and contrasted. Am J Hosp Palliat Care. 2011;28(5):378-83. doi: 10.1177/1049909111410298

  2. Mckinley EC, Richardson EJ, Mcgwin G, Zhang J. Evaluating the effectiveness of antidepressant therapy adjuvant to gabapentin and pregabalin for treatment of SCI-related neuropathic pain. J Spinal Cord Med. 2018;41(6):637-644. doi:10.1080/10790268.2017.1415246

Additional Reading
  • Markman J, et al. Tratment of Pain. Merck Manual Professional Version.

  • 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.