Antidepressants: Another weapon against chronic pain

Some of the more effective and commonly used medications for chronic pain are drugs that were developed to control other conditions. Although not Food and Drug Administration approved to treat chronic pain, antidepressants are a mainstay in the treatment of many chronic pain conditions — even when depression isn't a factor.

Types of pain relieved

Antidepressants seem to work best for pain caused by:

• Arthritis
• Nerve damage from diabetes (diabetic neuropathy)
• Nerve damage from shingles (postherpetic neuralgia)
• Tension headache
• Migraine
• Fibromyalgia
• Low back pain
• Pelvic pain

The painkilling mechanism of these drugs is still not fully understood. Antidepressants may increase neurotransmitters in the spinal cord that reduce pain signals. But they don't work immediately. You may feel some relief from an antidepressant after a week or so, but maximum relief may take several weeks. Pain relief from antidepressants generally is moderate.

Antidepressants are classified based on their chemical structure and how they work. One of the most effective groups of antidepressants for pain is known as tricyclic because of the chemical structure.

Tricyclic antidepressants

Tricyclic antidepressants are the most effective type of antidepressant used for pain. They include:

• Amitriptyline
• Imipramine (Tofranil)
• Clomipramine (Anafranil)
• Nortriptyline (Pamelor)
• Desipramine (Norpramin)

Side effects of tricyclic antidepressants

Side effects of tricyclic antidepressants may include:

• Blurred vision
• Drowsiness
• Dry mouth
• Constipation
• Weight gain
• Difficulty urinating
• Changes in blood pressure

To reduce or prevent side effects, your doctor will likely start you at a low dose and slowly increase the amount. Most people are able to take tricyclic antidepressants, particularly in low doses, with only mild side effects. The doses that are effective for pain are typically lower than the doses used for depression.

Other antidepressants that may help

Other classes of antidepressants have become more popular because they have fewer side effects. These drugs also may be used to help relieve chronic pain:

• Serotonin and norepinephrine reuptake inhibitors (SNRIs). Drugs such as venlafaxine (Effexor) and duloxetine (Cymbalta) don't work quite as well as tricyclic antidepressants, but they also don't produce as many side effects.
• Selective serotonin reuptake inhibitors (SSRIs). Drugs such as paroxetine (Paxil) and fluoxetine (Prozac) don't appear to help relieve pain on their own. However, fluoxetine may boost the painkilling effects of some tricyclic antidepressants.

Related

• Biofeedback
• Chronic pain can interfere with sexuality