What to Know About Cymbalta (Duloxetine)

A SNRI to Treat Depression and Anxiety

Older man taking pills on bed. David Burton/ GettyImages

Cymbalta (duloxetine hydrochloride) is a serotonin-norepinephrine reuptake inhibitor (SNRI) antidepressant. It is taken by mouth as a pill or capsule. Cymbalta may help improve a number of symptoms of depression including mood, appetite, sleep, and energy levels. 

As an SNRI, duloxetine inhibits the reuptake of the neurotransmitters serotonin and norepinephrine in the central nervous system. Cymbalta works by increasing the amounts of the neurotransmitters serotonin and norepinephrine. These brain chemicals work to help regulate mood, so increasing the amount of them in the brain can help relieve symptoms of depression.

Uses

Cymbalta is used for the treatment of major depressive disorder. The effectiveness of Cymbalta for longer-term use, or more than nine weeks, has not been systematically evaluated in clinical trials. It is also used for the management of diabetic peripheral neuropathic pain, fibromyalgia, chronic muscle and bone pain, and generalized anxiety disorder.

Off-Label Uses

Cymbalta may sometimes be prescribed off-label in the treatment of stress urinary incontinence, chronic fatigue syndrome, and lower back pain. 

Before Taking

Cymbalta can be effective in the treatment of moderate-to-severe depression. Before you decide if duloxetine is right for you, your doctor will evaluate your symptoms and health history. Your doctor will want to determine if you have any other health conditions that may preclude the use of this medication or if you are taking any other medications or supplements that may influence the drug's actions.

Before you begin taking Cymbalta, you should be aware that it may cause sudden decreases in blood pressure, which can result in dizziness and falling. You should use caution when standing.

Cymbalta may also cause you to feel drowsy, so you should avoid operating a vehicle or other heavy equipment until you are aware of how the drug may affect you.

Because duloxetine may increase suicidal thinking or behaviors in some individuals, you should talk to your doctor about monitoring your symptoms, particularly after you first begin taking the drug or any time your dosage is adjusted.

Precautions and Contraindications

There have been some reports of liver failure in patients using Cymbalta. It has also been associated with an increase in blood pressure, so blood pressure should be monitored throughout treatment. Cymbalta should be used with caution in patients with a history of mania or seizures. It should not be used in those with uncontrolled narrow-angle glaucoma. It should be discontinued gradually to avoid discontinuation symptoms. Experience with Cymbalta in patients with other illnesses is limited.

Caution should be used when taking Cymbalta with other serotonergic medications such as other antidepressants. When taken with other drugs that affect serotonin, there is a risk of a serious complication known as serotonin syndrome. Symptoms of serotonin syndrome include increased blood pressure, elevated heart rate, sweating, loss of coordination, agitation, and confusion. If you experience any of these symptoms while taking Cymbalta, you should contact your doctor immediately. 

Cymbalta should not be used by anyone who has shown a sensitivity to duloxetine or any of Cymbalta's inactive ingredients. It should also not be used at the same time as a monoamine oxidase inhibitor (MAOI) antidepressant. In clinical trials, Cymbalta was associated with increased mydriasis, which is dilation of the pupil of the eye, in patients with uncontrolled narrow-angle glaucoma and should not be used by patients with this condition.

Other SNRIs

Other SNRIs that are currently approved in the treatment of depression include:

  • Strattera (atomoxetine)
  • Pristiq; Khedezla (desvenlafaxine)
  • Irenka (duloxetine)
  • Fetzima (milnacipran)
  • Ultram (tramadol)
  • Effexor XR (venlafaxine)

Dosage

Cymbalta should be administered at a total daily dose of 40-60 mg/day. Generally, it will be split into two doses taken at different times of the day. It is not necessary to take it with food. There is no evidence that doses greater than 60 mg/day confer any additional benefits.

How to Take

The delayed-release capsules should be swallowed whole and never crushed or chewed. If you miss a dose of duloxetine, you should take it as soon as you remember, unless it is close to the time for your next dose. In that case, simply skip the missed dose and take your regular dose on schedule. 

Never take two doses at once to make up for a missed dose, as it may result in an accidental overdose. Symptoms of a Cymbalta overdose include sleepiness, seizures, vomiting, rapid heart rate, confusion, and coma. You should contact emergency services immediately if you believe that you or someone else has overdosed on Cymbalta.

Side Effects

Common

Some of the most common side effect associated with duloxetine are:

  • Nausea
  • Dry mouth
  • Headache
  • Dizziness
  • Sleepiness

The most common adverse events, reported by greater than 5%, were nausea, dry mouth, constipation, decreased appetite, fatigue, sleepiness, and increased sweating.

Adverse events occurring in at least 2% of patients included diarrhea, vomiting, weight loss, dizziness, tremor, hot flushes, blurred vision, insomnia, anxiety, and sexual side-effects.

Severe

More serious side effects can include:

  • Bruising or bleeding
  • Swelling
  • Abdominal pain
  • Jaundice
  • Chest pain
  • Trouble breathing
  • Dark urine
  • Panic attack
  • Worsening depression

If you experience any serious side effects, you should contact your doctor immediately as they may be a sign of a potentially dangerous complication.

Warnings and Interactions

All antidepressants, including Cymbalta, are required to carry a black box warning that antidepressants may increase the risk of suicide in people under the age of 25.

Patients should be observed closely for worsening depression and suicidality, especially at the beginning of treatment or when dose changes are made. Patients should also be monitored for symptoms such as anxiety, agitation, restlessness, panic attacks, insomnia, irritability, hostility, impulsivity, hypomania, and mania.

If such symptoms are severe, occur suddenly or were not symptoms that were present before treatment began, consideration should be given to changing the patient to a different medication.

Drug Interactions

Duloxetine can interact with a number of other medications and supplements. These substances may impact the way that your antidepressant works or your antidepressant may influence the effects of those substances.

In order to minimize the risk of potentially dangerous interactions, you should always tell your doctor about any other prescription medications, over-the-counter drugs, vitamins, herbs, or other supplements that you might be taking. 

Drugs that are known to interact with duloxetine include:

  • MAOIs
  • Warfarin and other blood thinners
  • Other antidepressants
  • Pain relievers such as aspirin and ibuprofen
  • Blood pressure medications
  • Diuretics
  • Heartburn medications
  • St. John's wort
  • Some antibiotics

Visit the FDA's website or speak with your doctor or pharmacist for more information on potential drug interactions.

Carcinogenesis, Mutagenesis, Impairment of Fertility

In female mice receiving an equivalent of 11 times the maximum recommended human dose (MRHD), there was an increase in hepatocellular adenomas and carcinomas. The no-effect dose was 4 times the MRHD. Tumor incidence was not increased in male mice at doses up to 8 times the MRHD. It was not mutagenic in studies performed nor did it affect fertility.

Pregnancy and Lactation

Cymbalta is a Class C drug. There are no adequate and well-controlled studies in pregnant women, so duloxetine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Drug Abuse and Dependence

Duloxetine is not a controlled substance. In animal studies, it did not demonstrate barbiturate-like abuse potential. In drug dependence studies, it did not demonstrate dependence-producing potential in rats. While Cymbalta has not been systematically studied in humans for its potential for abuse, there were no indications of drug-seeking behavior in the clinical trials.

Never stop taking your antidepressant without first consulting your doctor. Your doctor can advise you about how to reduce or stop your medication, which may involve gradually reducing your dosage.

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