Introduction
Duloxetine is a prescription medication in the SNRI family, a group that acts on two neurotransmitters in the brain and nervous system: serotonin and norepinephrine. In the United States it is sold under the brand name Cymbalta and as generic duloxetine, in strengths such as 30 and 60 milligrams, available by prescription only.
Because of its dual action, duloxetine is not only an antidepressant; it is also used for anxiety and for several types of chronic and nerve pain. This article explains what it is used for, how it works, its side effects and warnings, and what to know about taking and stopping it. The information is general and does not replace medical advice or the prescribing information.
What Duloxetine Is Used For
In the United States, duloxetine is FDA-approved for several conditions, some psychiatric and some pain-related: • Major depressive disorder in adults. • Generalized anxiety disorder in adults and in children aged 7 and older. • Diabetic peripheral neuropathic pain in adults. • Fibromyalgia in adults and in pediatric patients aged 13 and older. • Chronic musculoskeletal pain in adults, such as chronic low back pain or pain from osteoarthritis.
The key point is that it is not only a depression medication. Because of its effect on norepinephrine and serotonin, it also acts on pain pathways in the nervous system, which is why it is used for chronic and nerve pain. The specific indication is decided by the doctor based on the patient's condition.
How Duloxetine Works
Duloxetine increases the availability of serotonin and norepinephrine in the nervous system by inhibiting their reuptake. Both of these neurotransmitters are involved in regulating mood and anxiety and in processing pain signals in the brain and spinal cord.
Its effect on pain pathways explains why the drug can help in chronic pain conditions, not only in depression and anxiety. However, it is not an immediate painkiller, and the effect develops gradually.
How Long Until It Works
The effect usually begins to appear after 2 to 4 weeks of regular treatment. For nerve pain it can sometimes take longer. Some people feel improvement earlier, but not always.
It is important to continue treatment as directed even if there is no noticeable improvement at first, and not to stop on your own. If there is no improvement after several weeks, tell your doctor.
Common Side Effects
Like any medication, duloxetine has side effects. Among the common ones: • Nausea. • Dry mouth. • Constipation or diarrhea. • Headache. • Fatigue or drowsiness. • Increased sweating. • Decreased appetite or weight change. • Reduced libido or sexual difficulty.
Some effects ease after the first weeks. If an effect is strong or does not pass, talk to your doctor or pharmacist, and do not stop the medication on your own.
Important Warnings
Antidepressants, including duloxetine, carry an FDA boxed warning for an increased risk of suicidal thoughts and behaviors in children, adolescents and young adults up to age 24. This risk is highest at the start of treatment and when the dose changes. Seek help promptly for worsening depression, suicidal thoughts, aggression, unusual restlessness or a sharp change in behavior.
Do not stop duloxetine all at once without a doctor. Stopping suddenly can cause discontinuation symptoms such as dizziness, nausea, headache, irritability, sleep problems and a general unwell feeling, so the dose is usually lowered gradually.
Use special caution with liver disease, severe kidney disease, significant alcohol use, narrow-angle glaucoma, a history of seizures, mania or bipolar disorder, a tendency to bleed, or low blood sodium. The prescribing information advises against use in significant hepatic impairment and in severe renal impairment.
Drug Interactions
Tell your doctor and pharmacist about every medication, supplement or herbal product you take. Combinations that need special caution: • MAOI medications: must not be combined, and a waiting period between drugs is required, because of the risk of serotonin syndrome. • Other drugs that raise serotonin, such as other SSRIs or SNRIs, tramadol, fentanyl, migraine triptans, lithium and St. John's wort: because of the risk of serotonin syndrome. • Blood thinners and nonsteroidal anti-inflammatory drugs such as aspirin, ibuprofen and naproxen: because of an increased bleeding risk. • Certain heart-rhythm drugs, some antidepressants and antibiotics such as ciprofloxacin, which can raise the drug's blood level.
This list is not complete. Only your doctor or pharmacist can assess all interactions for your individual situation.
How to Take It
Duloxetine is usually taken as a capsule swallowed whole with water. Do not chew, crush or open the capsule, because it is designed for delayed release and to withstand stomach acid.
A common dose in many conditions is around 60 milligrams once a day, but treatment is sometimes started at 30 milligrams to reduce side effects, with gradual adjustment. The dose, timing and length of treatment are set by the doctor only, and should not be changed on your own.
When to See a Doctor
During treatment with duloxetine, some situations call for prompt medical attention, and some are urgent.
Contact your doctor when
- Side effects are strong or do not pass.
- There is no improvement after several weeks, or the condition worsens.
Seek urgent help when
- Suicidal thoughts, a sharp worsening of depression or an extreme behavior change appear.
- Signs of serotonin syndrome appear: confusion, fever, tremor, fast heartbeat, stiff muscles and sweating.
- Signs of unusual bleeding, a severe rash, or swelling of the face and throat appear.
If you or someone you know has thoughts of self-harm, call or text the 988 Suicide and Crisis Lifeline. In a medical emergency, call 911.
FAQ
Why would I be given duloxetine if I am not depressed?
Beyond depression and anxiety, duloxetine acts on pain pathways in the nervous system through its effect on serotonin and norepinephrine. That is why it is also prescribed for neuropathic pain, fibromyalgia and chronic musculoskeletal pain, even without depression.
How long does duloxetine take to work?
The effect usually begins after 2 to 4 weeks, and for nerve pain it can take longer. It is important to keep taking it and not to stop without a doctor.
Can I stop duloxetine on my own?
No. Stopping suddenly can cause discontinuation symptoms such as dizziness, nausea and headache. Stopping is done gradually and with a doctor's guidance.
What are the common side effects?
Nausea, dry mouth, constipation or diarrhea, headache, drowsiness, sweating, and changes in appetite or sexual function. Many ease after the first weeks.
Which drugs should not be combined with duloxetine?
MAOI medications must not be combined, and caution is needed with other drugs that raise serotonin and with blood thinners. Tell your doctor and pharmacist about every medication you take.
Summary
Duloxetine (Cymbalta) is a prescription SNRI that can fit both psychiatric conditions such as depression and anxiety and chronic and nerve pain, thanks to its effect on serotonin and norepinephrine. The effect develops gradually, usually within 2 to 4 weeks.
The medication can be effective, but it needs individual adjustment, an interaction check and caution at the start and when stopping. Do not start, change or stop it without a doctor, and with any worrying sign, especially suicidal thoughts, seek help right away.
References
- U.S. Food and Drug Administration. Cymbalta (duloxetine) prescribing information. Source: www.accessdata.fda.gov
- Dhaliwal JS, et al. Duloxetine. StatPearls, NCBI Bookshelf. Source: www.ncbi.nlm.nih.gov
- MedlinePlus. Duloxetine. Source: medlineplus.gov
- DailyMed. Duloxetine delayed-release capsule. Source: dailymed.nlm.nih.gov
- Drugs.com. Cymbalta (duloxetine) FDA approval history. Source: www.drugs.com
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