Examples

Tricyclic antidepressants

Serotonin and norepinephrine reuptake inhibitors (SNRIs)

Selective serotonin reuptake inhibitors (SSRIs)

How It Works

Antidepressant drugs increase levels of the chemicals produced in the brain to improve your mood. Lower doses relieve pain and may help you sleep.

Why It Is Used

In low doses, antidepressants relieve chronic pain and pain related to the peripheral nervous system (neuropathic pain), such as cancer pain. They may also cause drowsiness, which may improve sleep and relieve fatigue.

In higher doses, antidepressants can help to relieve symptoms of depression.

How Well It Works

Some people find that low doses of antidepressants help relieve cancer pain. Researchers are still exploring whether and how well antidepressants affect cancer pain. These drugs can improve sleep. This, in turn, may improve your ability to manage your pain. ¹

Side Effects

Different antidepressants have different side effects. If you have severe side effects from one drug, your doctor may give you a different one.

Most side effects decrease over time. They may include:

• Constipation. Make sure you drink enough fluids while you are taking any of these drugs. Most adults should drink between 8 and 10 glasses of water or noncaffeinated beverages each day. Include fruits, vegetables, and fiber in your diet each day.
• Diarrhea.
• Dry mouth.
• Nausea.
• Changes in appetite or weight.
• Nervousness or anxiety.
• Blurred vision or glaucoma that gets worse.
• Drowsiness or insomnia.
• Low blood pressure.
• Tremors and sweating.
• Urinary retention.
• Headache.
• Decreased sex drive, impotence, or difficulty having an orgasm.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

FDA Advisories. The U.S. Food and Drug Administration (FDA) has issued:

• An advisory on antidepressant medicines and the risk of suicide. The FDA does not recommend that people stop using these medicines. Instead, a person taking antidepressants should be watched for warning signs of suicide. This is especially important at the beginning of treatment or when doses are changed.
• A warning about the antidepressants Paxil and Paxil CR and birth defects. Taking these medicines in the first 12 weeks of pregnancy may increase your chance of having a baby with a birth defect.

What To Think About

Studies have found that daily use of SSRIs may increase the risk of bone fracture in adults over age 50. Before taking an SSRI, talk to your doctor about this risk.

Amitriptyline is the most common antidepressant that is used to treat cancer pain. It may cause side effects, such as dry mouth, drowsiness, constipation, or difficulty urinating.

You may start to feel better within 1 to 3 weeks of taking antidepressant medicine. But it can take as many as 6 to 8 weeks to see more improvement. If you have questions or concerns about your medicines, or if you do not notice any improvement by 3 weeks, talk to your doctor.

People with cancer pain and depression are often treated with one of the following:

• Selective serotonin reuptake inhibitor (SSRI), such as sertraline ( Zoloft), fluoxetine ( Prozac), or paroxetine (Paxil)
• Serotonin and norepinephrine reuptake inhibitor (SNRI), such as venlafaxine ( Effexor) or duloxetine ( Cymbalta)
• Higher dosage of tricyclic antidepressant than is used for cancer pain alone

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.

Citations

1. Abramowicz M (2007). Drugs for pain. Treatment Guidelines From the Medical Letter, 5(56): 23-32.