What to Know About Cymbalta (Duloxetine)

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 and as a result, increasing the amounts available in the brain. These brain chemicals work to help regulate mood, so increasing their levels 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 musculoskeletal 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.

Precautions and Contraindications

There have been some reports of liver injury in patients using Cymbalta, particularly in those with pre-existing liver damage. It has also been associated with an increase in blood pressure, more likely at higher doses, so blood pressure should be monitored throughout treatment. Cymbalta should be used with caution in people 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.

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 (dilation of the pupil of the eye) in people with uncontrolled narrow-angle glaucoma and should not be used by people with this condition.

Other SNRIs

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

• Pristiq; Khedezla (desvenlafaxine)
• Fetzima (milnacipran)
• Effexor XR (venlafaxine)

Dosage

Cymbalta is often administered to a target daily dose of 60 milligrams (mg). Sometimes your doctor will recommend higher doses. It may be split into two doses taken at different times of the day to minimize side effects. It is not necessary to take it with food. There is no clear evidence that doses greater than 60 mg per day confer any additional benefits.

The listed dosages are according to the drug manufacturer. Check your prescription and talk to your doctor to make sure you are taking the right dose for you.

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 which 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. Symptoms of a Cymbalta overdose include sleepiness, seizures, vomiting, rapid heart rate, confusion, and coma.

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

Warnings and Interactions

All antidepressants, including Cymbalta, are required to carry a black box warning that antidepressants may increase the risk of suicidal thoughts and behaviors in children and young adults under the age of 25.

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

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

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 Use and Dependence

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