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Duloxetine (Cymbalta®)

Duloxetine (Cymbalta® and generic forms) belongs to a group of medications called “antidepressants.”

What is this medication used for?

Duloxetine is not approved by Health Canada for use in children and adolescents.

However, duloxetine may help treat depression, generalized anxiety disorder, depression associated with body pain and other pain conditions like fibromyalgia and neuropathic pain.

When potential benefits outweigh risks, duloxetine may be prescribed “off-label.” Learn more about off-label medication use:

Tell your doctor or pharmacist if you:

  • Have allergies or bad reactions to a medication
  • Take (or plan to take) other prescription or non-prescription medications, including natural medicines. Some medications interact with duloxetine. Your doctor may adjust medication doses or monitor for side effects
  • Have a history (or family history) of heart, kidney or liver disease, seizures, bipolar disorder, diabetes or glaucoma
  • Have problems urinating, high blood pressure or a bleeding disorder
  • Have a fructose or glucose intolerance
  • Miss a menstrual period, are pregnant, breast-feeding or planning a pregnancy
  • Use alcohol or street drugs. Taking duloxetine together with certain substances may cause a bad reaction. Learn more at

When will the medication start to work?

You (or your family members) may notice improvements within 1 to 4 weeks. However, it may take 3 to 6 weeks before you begin to feel better. Full beneficial effects may take 4 to 8 weeks or longer.

Duloxetine takes time to work. Continue taking duloxetine as prescribed, even if you are feeling better. Talk with your doctor before you increase, decrease or stop taking duloxetine.

This medication is not addictive. Do not stop taking it before talking to your doctor.

Possible common or serious side effects:

Side effects may be more common when starting a medication or after a dose increase. Talk to your doctor, nurse or pharmacist if any side effect concerns you.

  • Nausea, stomach ache or constipation
  • Decreased appetite or dry mouth
  • Fatigue or lack of energy
  • Dizziness, drowsiness, and headache
  • Trouble sleeping or abnormal dreams
  • Increased sweating
  • In adolescents/adults: changes in sexual performance or interest

Contact your doctor immediately if you experience:

  • Thoughts of hurting yourself, hostility, or suicide
  • Changes in mood to an unusual state of excitement, irritability, or happiness
  • Confusion or difficulty remembering things along with muscle aches, stiffness, and lack of coordination
  • Uncomfortable sense of inner restlessness or agitation
  • Unexpected rash, seizure, fever or excessive sweating
  • Unusual bruising or bleeding

How do I take this medication?

Duloxetine is usually taken once daily with or without food, at the same time each day. Usually, you will start with a low dose and slowly increase this dose over several days to weeks, based on how you tolerate it.

Delayed-release duloxetine capsules should be swallowed whole with fluid. Do not sprinkle the contents of the capsule(s) on food or mix with liquids. The capsules should not be opened, divided, crushed, chewed, or placed in water.

What precautions should my doctor and I be aware of when taking this medication?

  • While taking duloxetine, if you feel dizzy, drowsy, or slowed down, do not drive a car or operate heavy machinery. Alcohol could make this worse. Try to avoid alcohol while taking duloxetine.
  • Duloxetine and medications like it are associated with a rare side effect called “serotonin syndrome,” especially when used in combination with other serotonergic drugs such as amphetamines, triptans, and most other antidepressants. Symptoms include diarrhea, sweating, increased heart rate, tremors, severe muscle stiffness, and increased agitation.
  • Do not to stop taking duloxetine suddenly. Stopping abruptly is associated with “antidepressant discontinuation syndrome.” This involves flu-like symptoms, trouble sleeping, nausea, irritability, headache, and abnormal sensations that feel like electric shocks, burning, tingling, or numbness. If stopping or changing medications, your dose should be reduced slowly.

How does this medication work?

Duloxetine is a Serotonin and Norepinephrine Reuptake Inhibitor (SNRI). Like other SNRIs, duloxetine increases levels of the brain chemicals serotonin and norepinephrine. These brain chemicals do not function properly in people who have depression or anxiety. Duloxetine may also increase levels of another brain chemical, dopamine. The exact way that duloxetine improves symptoms of depression, anxiety disorders, and pain conditions is not known.

What special instructions should I follow while using this medication?

  • Keep all appointments with your doctor and the lab.
  • Your doctor may want to talk to you within 1-2 weeks after starting duloxetine, and meet with you over time to make sure it is working well for you and check for side effects.
  • Do not allow anyone else to use your medication.

What should I do if I forget to take a dose of this medication?

If you forget to take a dose of duloxetine, take the missed dose as soon as you remember. However, if it is within 4 hours of your next scheduled dose, skip the missed dose and continue with your regular schedule. DO NOT double your next dose to try to ‘catch up’.

How do I store this medication?

Keep duloxetine in the original container, stored at room temperature away from moisture and heat and protected from light. Keep duloxetine out of reach and sight of children.

How well does the medication work in children and adolescents?

Duloxetine has been studied in children and adolescents with depression and anxiety disorders. It has been shown to be better than placebo (an inactive pill) for the treatment of generalized anxiety disorder in children and adolescents. However, there are mixed results regarding the use of duloxetine in depression. Evidence supports the use of duloxetine in adolescents with juvenile fibromyalgia. Whenever possible, the addition of talk therapy such as Cognitive Behavioural Therapy (CBT) may help increase the potential for benefit.

How long should I take the medication for?

This depends on the symptoms you have, how frequently they occur, and how long you have had them. Most people need to take duloxetine for at least 6 months. This allows time for symptoms to stabilize and function to improve. After this time, you and your doctor can discuss the benefits and risks of continuing treatment.

If you have severe anxiety or juvenile fibromyalgia and you tolerate duloxetine well, you may be asked to take duloxetine on an ongoing basis. Continuing treatment will significantly decrease the chance that your anxiety or pain symptoms will return in the future.

Do not increase, decrease, or stop taking duloxetine without discussing it with your doctor, even if you are feeling better. If you stop taking duloxetine suddenly, it is possible that your symptoms may return or you may have a bad reaction.

TIP: Use the Kelty Mental Health Antidepressant Monitoring Form for Children and Adolescents to help measure your progress on this medication.

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