Pain and depression are often comorbidities; that is, they exist together with one feeding the other in a vicious cycle. Chronic pain patients are more likely to develop depression as a result of their condition than others. New research on antidepressants may hold the key to treating both chronic pain and the pain that arises as a result of depression.
When a person is injured or has a condition that results in chronic pain, the brain actually changes. Neurotransmitters begin to make the body more sensitive to pain signals, and the person may feel aches and pains that are unrelated to the previous injury or pain-causing condition. This increased sensitivity can lead to other things such as trouble sleeping. The cycle of chronic pain leads to stress, which then leads to fatigue, which finally leads to mood or anxiety disorders, and a chronic pain sufferer may begin to feel clinically depressed.
The doctor treating the chronic pain may not be able to distinguish depression from chronic pain. Similarly, a therapist working with a depressed patient may assume that the chronic pain is a result of the aches of depression: tense muscles and slumped posture that can lead to pain. Many depressed patients complain of pain, but the therapist may assume it is episodic (new to the depression) and not chronic (lasting longer than three months). This missed diagnosis makes it very difficult to effectively treat either condition.
Even when depression is not diagnosed or present, many pain specialists are turning to antidepressants to treat chronic pain.
The way that antidepressants treat pain is still not fully understood, but it may have something to do with the way they stimulate serotonin production in the brain. Antidepressants are most commonly prescribed for the following types of pain:
- Diabetic neuropathy
- Migraine headaches
- Facial pain
- Low back pain
- Post herpetic neuralgia
- Nerve pain, including peripheral neuropathy and pain from stroke or spinal cord injury
- Pelvic pain
There are different types of antidepressants, and just as with prescribing for depression, it may take a few tries to find the one that works best.
Tricyclic antidepressants are used most often for chronic pain. These include amitriptyline (Elavil), imipramine (Tofranil), clomipramine (Anafranil), doxepin (Adapin), nortriptyline (Pamelor), and desipramine (Norpramin). As with any prescription, there is the risk of side effects that can include fatigue, weight gain, drowsiness, lightheadedness, nausea, constipation, and blurred vison. The dosage for chronic pain is typically much lower than the dosage for depression. The doctor will start with an even lower dose and increase it as necessary. Because of this, it could take several weeks for any pain relief to occur.
Serotonin and norepinephrine reuptake inhibitors (SNRIs) have the added benefit of treating both pain and depression. The low doses used to treat chronic pain have also been proven effective at treating depression. Venlafaxine (Effexor), duloxetine (Cymbalta), and milnacipran (Savella) are common SNRIs.
Each has their own potential side effects, so it is important to consider them.
- Venlafaxine: May worsen any heart issues that are already present and cause drowsiness, insomnia, or high blood pressure.
- Duloxetine: Side effects can include nausea, dry mouth, insomnia, dizziness, excessive sweating, or constipation.
- Milnacipran: Commonly prescribed only for fibromyalgia, as it has not proven to be as effective against other types of chronic pain. Side effects can include nausea and drowsiness.
Selective serotonin reuptake inhibitors (SSRIs) such as paroxetine (Paxil) and fluoxetine (Sarafem, Prozac) have only demonstrated effectiveness when paired with tricyclic antidepressants. The benefit of these types of medications is that they don’t tend to come with severe side effects, an important consideration.
It is important to monitor mental health when taking these medications, as they can come with an increased risk of suicidal thoughts or actions. Do not take these unless under the supervision of a doctor who is familiar with all other medications you are taking, and talk to a doctor immediately if you experience any of the side effects mentioned above.
If you are considering an antidepressant as treatment for chronic pain, there are important things to consider.
- The length of pain: If pain is episodic and not chronic, antidepressants are not the best choice. Antidepressants can take as many as six to eight weeks to begin to work. Often episodic pain is resolved in that time.
- The type of pain: Some antidepressants work better for one type of pain than another. It is important to determine which is best for the type of pain you have.
- The risk of side effects versus the benefit of the medication: Some antidepressants, especially the older tricyclic antidepressants, have a high risk of side effects that can be debilitating for a time until the dosage is correctly calibrated. You need to consider if the benefits outweigh the risks. You should also consider whether or not you are willing to potentially try multiple prescriptions to get the correct fit and dose for your chronic pain.
There are some side effects that should not be ignored. In addition to thoughts of suicide or self-harm, call your doctor immediately if you experience the following:
- Difficulty breathing or swallowing
- Agitation or fast heartbeat
- Nausea and vomiting
- Hives anywhere on the body
Antidepressants can help ease chronic pain; have you tried them as part of your treatment plan? If not, would you consider them?
Image by Steve Snodgrass via Flickr