Duloxetine

Key facts

• Duloxetine (sold as Cymbalta and as generics) is an SNRI, a serotonin-norepinephrine reuptake inhibitor, used for major depressive disorder, generalized anxiety disorder, diabetic nerve pain, fibromyalgia and chronic musculoskeletal pain.
• You take it once daily, with or without food; pain relief can start within 1 to 2 weeks, while mood benefits usually take 4 to 6 weeks.
• Duloxetine can cause liver injury. Avoid it if you have liver disease or drink alcohol heavily, and report dark urine, yellowing skin or persistent nausea to your prescriber right away.
• In people under 25, duloxetine can increase suicidal thoughts and behaviour, especially early in treatment. Seek urgent care for high fever, agitation or muscle rigidity, which can signal serotonin syndrome.

What duloxetine treats

Duloxetine treats major depressive disorder and generalized anxiety disorder. It is also a first-line treatment for diabetic peripheral neuropathy (nerve pain from diabetes), fibromyalgia, and chronic musculoskeletal pain such as osteoarthritis and chronic low back pain.

How duloxetine works

Nerve cells release serotonin and norepinephrine, chemical messengers involved in mood and in how pain signals are processed, and then reabsorb them. Duloxetine blocks that reabsorption (reuptake), so more of both stay active between nerve cells. This eases mood symptoms and dampens pain signals travelling through the spinal cord.

Before you take it

• Never take duloxetine within 14 days of a monoamine oxidase inhibitor (MAOI); the combination can cause serotonin syndrome, which can be fatal.
• Do not use duloxetine if you have liver disease or uncontrolled glaucoma. Tell your prescriber about heavy alcohol use, kidney disease, a seizure history or blood thinners, which raise bleeding risk.
• Your prescriber may check liver function before and during treatment, especially if you drink alcohol regularly.
• Never stop duloxetine suddenly. Taper the dose down gradually under medical guidance to avoid dizziness, nausea and flu-like withdrawal symptoms.

Side effects

Common effects, often easing after the first few weeks: nausea, dry mouth, drowsiness or insomnia, sweating and reduced sex drive.

Stop and seek urgent medical care for any of these:

• New or worsening suicidal thoughts, especially if you are under 25.
• Dark urine, yellowing skin or eyes, or persistent nausea and stomach pain (possible liver injury).
• Agitation, high fever, fast heartbeat, muscle twitching or confusion (serotonin syndrome).
• Unusual bleeding, severe rash, swelling or difficulty breathing.

Safety essentials

• Duloxetine can injure the liver. Avoid it with liver disease or heavy alcohol use, and stop and seek care for dark urine, yellowing skin or unexplained nausea.
• This class carries a warning for increased suicidal thinking in people under 25, particularly in the first weeks of treatment.
• Never combine duloxetine with an MAOI, and taper off slowly rather than stopping abruptly.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.