What to Know About Cymbalta (Duloxetine)

Cymbalta (duloxetine hydrochloride) is an antidepressant in the serotonin-norepinephrine reuptake inhibitor (SNRI) category. It is taken by mouth, as a pill or capsule, and can be prescribed for certain depression and anxiety disorders. 

If you've been given a prescription for Cymbalta or want to learn more about whether it is right for you, it's helpful to understand how this antidepressant works. We also discuss how to take Cymbalta safely, which involves knowing its precautions and contraindications, as well as its potential side effects.

How Cymbalta Works

As an SNRI, duloxetine inhibits the reuptake of the neurotransmitters serotonin and norepinephrine in the central nervous system. As a result, this increases the amounts available in the brain.

These brain chemicals help regulate mood. So, increasing their levels can relieve symptoms of depression and anxiety. A 2020 review of 85 studies determined that duloxetine is effective for these purposes, both as a short- and long-term treatment.

Improvements in sleep, energy levels, and appetite may be noticed within the first one or two weeks of starting this drug; while other depression and anxiety symptoms may take up to eight weeks to improve.

Uses for Cymbalta

The U.S. Food and Drug Administration has approved Cymbalta for use in the treatment of two mental health conditions: major depressive disorder (MDD) and generalized anxiety disorder (GAD). It is also approved to help treat fibromyalgia, diabetic peripheral neuropathy, and chronic musculoskeletal pain.

Before Taking Cymbalta

Before prescribing duloxetine, your healthcare provider will evaluate your symptoms and health history. This can help 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.

This is also a good time to become familiar with the warnings, contraindications, and interactions of this drug so you know how to use it safely. Learning its potential side effects is important too, one of which is an increased risk of suicidal thoughts or behaviors in children, teens, and young adults.

Warnings and Precautions for Cymbalta

All antidepressants, including Cymbalta, are required to carry a black box warning. This warning states that antidepressants may increase the risk of suicidality 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 and when changes are made to their prescribed dose. Symptoms to watch for include anxiety, agitation, restlessness, panic attacks, insomnia, irritability, hostility, impulsivity, and hypomania or mania.

Additional warnings for Cymbalta include a potential risk of:

• Abnormal bleeding
• Fasting blood sugar increases in people with diabetes
• Liver failure
• Low blood sodium levels (hyponatremia)
• Sudden drops in blood pressure, or blood pressure increases
• Urinary retention

Serotonin Syndrome

Caution should be used when taking Cymbalta with other medications that increase serotonin, which includes other antidepressants. When taken with drugs that also affect serotonin levels, there is a risk of a serious complication known as serotonin syndrome.

Symptoms of serotonin syndrome can develop in minutes or hours and include increased blood pressure, elevated heart rate, sweating, loss of coordination, agitation, and confusion. You might also experience hallucinations, have overactive reflexes, or have abnormal eye movements.

Contraindications for Cymbalta

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), or within 14 days of taking this type of drug.

In clinical trials, Cymbalta was associated with increased mydriasis (dilation of the pupil of the eye) in people with uncontrolled narrow-angle glaucoma. So, it should not be used by people with this condition.

Additionally, it is unclear as to whether it is safe to use Cymbalta when pregnant, with some studies finding that duloxetine may be associated with an increased risk of cardiac malformation in the fetus and postpartum hemorrhage. Therefore, it is recommended that the benefits be weighed against the risks before taking Cymbalta during pregnancy.

Drug Interactions for Cymbalta

Duloxetine can interact with a number of other medications and supplements. An interaction can impact the way that this antidepressant works or it may influence the effects of these other substances.

Drugs known to interact with duloxetine include:

• MAOIs and other antidepressants
• Warfarin and other blood thinners
• Migraine medications known as triptans
• Pain relievers, such as aspirin and ibuprofen
• Some antibiotics
• Heartburn medications
  

Potential Side Effects of Cymbalta

Although duloxetine is considered a safe drug and is generally well-tolerated, side effects can occur.

Common Side Effects

The most common adverse events associated with duloxetine, as reported by greater than 5% of users and appearing twice as often as for individuals taking a placebo or sham medication, include:

• Nausea
• Dry mouth
• Drowsiness
• Constipation
• Decreased appetite
• Excessive sweating

When first starting duloxetine, you might also feel faint, lightheaded, or dizzy when moving too quickly from a lying to a standing position. This is due to blood pressure changes. Getting up slowly can help ease this effect.

Severe Side Effects

More serious side effects of duloxetine can include:

• Abnormal bruising or bleeding
• Abdominal pain or swelling
• Yellowing of the eyes or skin
• Extreme fatigue or weakness
• Confusion or agitation
• Trouble walking or urinating
• Severe muscle twitching or stiffness
• Hallucinations
• Difficulty breathing or swallowing
• Fast or irregular heartbeat

Dosage of Cymbalta

When prescribed for depression or anxiety, Cymbalta is often administered to a target dose of 60 milligrams (mg) per day. The maximum dosage for this drug is 120 mg daily. However, higher doses of duloxetine are associated with more adverse effects without more positively impacting symptom reduction.

These dosages are according to the drug manufacturer. Check your prescription and talk to your healthcare provider to ensure that you are taking the right dose for you.

How to Take

The delayed-release capsules should be swallowed whole and never crushed or chewed. It is not necessary to take this medication with food.

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 this 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 is possible to overdose on this drug. Symptoms of a Cymbalta overdose can include rapid heart rate, seizures, and high blood pressure; when taken in high doses with other drugs, it can lead to low blood pressure and coma.

Cymbalta Misuse

There is a risk of becoming addicted to duloxetine or developing a tolerance to this drug. Both instances can lead to its misuse by causing a person to take more than is prescribed.

Misusing drugs can lead to greater side effects and the potential for overdose. That's why it's important to use Cymbalta as directed. Speak with your healthcare provider if you are concerned that you may be developing an addiction or tolerance to this drug.

Discontinuing Cymbalta

It is common to experience withdrawal symptoms after reducing the dosage of or completely stopping antidepressant drugs such as duloxetine. Some of the most reported Cymbalta withdrawal symptoms include:

• Dizziness
• Anxiety
• Nausea
• Trouble sleeping
• Irritability

Your physician can advise you about how to reduce or stop your medication, which may involve gradually reducing your dosage. The latter gives your body time to adjust to lower amounts of the drug before eliminating it altogether.