Duloxetine
Serotonin-Norepinephrine Reuptake Inhibitor (SNRI) – treats depression, generalized anxiety disorder, and diabetic neuropathic pain
Duloxetine is a prescription medication belonging to the serotonin-norepinephrine reuptake inhibitor (SNRI) class of antidepressants. It is widely prescribed for treating major depressive disorder, generalized anxiety disorder (GAD), and painful diabetic peripheral neuropathy. By increasing the activity of serotonin and norepinephrine in the brain, duloxetine helps regulate mood and reduce chronic pain signals. This evidence-based guide covers uses, dosage, side effects, drug interactions, and important safety information based on international clinical guidelines.
Quick Facts
Key Takeaways
- Duloxetine is an SNRI antidepressant that increases both serotonin and norepinephrine levels in the brain, making it effective for both mood disorders and chronic pain conditions.
- Therapeutic effects for depression and anxiety typically begin within 1–2 weeks, with full benefit often taking 4–6 weeks. For diabetic neuropathy, pain relief may take up to 2 months.
- Never stop duloxetine suddenly – your doctor should taper the dose gradually over at least 2 weeks to avoid withdrawal symptoms such as dizziness, nausea, and electric shock sensations.
- Important contraindications include use with MAO inhibitors, severe liver or kidney disease, and concurrent use of fluvoxamine, ciprofloxacin, or enoxacin.
- The most common side effects are nausea, headache, dry mouth and drowsiness – these are usually mild and tend to improve within the first few weeks of treatment.
What Is Duloxetine and What Is It Used For?
Duloxetine belongs to a class of medications known as serotonin-norepinephrine reuptake inhibitors (SNRIs). It works by blocking the reuptake of two important neurotransmitters – serotonin and norepinephrine – in the central nervous system. By preventing these chemical messengers from being reabsorbed into nerve cells, duloxetine increases their availability in the brain, which helps improve mood, reduce anxiety, and modulate pain signals.
This medication is approved for use in adults and is prescribed for several distinct conditions. In the treatment of major depressive disorder (MDD), duloxetine helps restore the balance of neurotransmitters that regulate emotional well-being. Depression affects approximately 280 million people worldwide according to the World Health Organization, and SNRIs like duloxetine represent an important treatment option, particularly for patients who have not responded adequately to selective serotonin reuptake inhibitors (SSRIs) alone.
For generalized anxiety disorder (GAD), duloxetine reduces the persistent and excessive worry that characterizes this condition. Clinical trials have demonstrated that duloxetine significantly reduces anxiety symptoms compared to placebo, with improvements typically measured using the Hamilton Anxiety Rating Scale (HAM-A). GAD is a chronic condition affecting approximately 3–5% of the general population, and duloxetine offers an evidence-based pharmacological approach to managing its symptoms.
Duloxetine is also indicated for painful diabetic peripheral neuropathy (DPNP), a type of nerve pain commonly experienced by people with diabetes. This pain is often described as burning, stabbing, tingling, or electric shock-like sensations, particularly in the feet and hands. The dual mechanism of duloxetine – affecting both serotonin and norepinephrine pathways – is particularly advantageous for pain management, as descending norepinephrine pathways play a key role in pain modulation within the spinal cord.
For most people with depression or anxiety, duloxetine begins to take effect within the first two weeks of treatment, though it may take 4–6 weeks before the full therapeutic benefit is experienced. It is important to continue taking the medication even after feeling better, as your doctor may recommend ongoing treatment to prevent relapse. For diabetic neuropathic pain, some improvement may be noticed within weeks, but it can take up to two months to assess the full response to treatment.
Duloxetine may also be approved for other conditions not listed here, such as fibromyalgia, chronic musculoskeletal pain, and stress urinary incontinence in some countries. Always follow your doctor's instructions regarding the use of this medication and consult your healthcare provider if you have questions about your specific treatment.
What Should You Know Before Taking Duloxetine?
Before starting duloxetine, it is essential to discuss your complete medical history and all current medications with your healthcare provider. Several important contraindications and precautions exist that may affect whether this medication is appropriate for you. Your doctor will evaluate your individual risk factors and determine the most suitable treatment approach.
Contraindications
You should not take duloxetine if any of the following apply:
- Allergy to duloxetine or any of the other ingredients in the medication
- Liver disease – duloxetine is extensively metabolized by the liver, and hepatic impairment significantly increases drug exposure and the risk of liver injury
- Severe kidney disease (estimated creatinine clearance below 30 mL/min) – reduced renal function impairs the elimination of duloxetine metabolites
- Current or recent use of MAO inhibitors – you must wait at least 14 days after stopping an MAO inhibitor before starting duloxetine, and at least 5 days after stopping duloxetine before starting an MAO inhibitor
- Concurrent use of fluvoxamine, ciprofloxacin, or enoxacin – these medications are potent CYP1A2 inhibitors that dramatically increase duloxetine blood levels
- Concurrent use of other duloxetine-containing products – avoid duplication of therapy
Inform your doctor if you have high blood pressure or heart disease, as duloxetine can cause small increases in blood pressure. Your doctor will determine whether duloxetine is appropriate given your cardiovascular health.
Warnings and Precautions
Duloxetine may not be suitable for everyone. Talk to your doctor before taking duloxetine if you:
- Are taking other medications for depression, including SSRIs, other SNRIs, or tricyclic antidepressants
- Are using St John's Wort (Hypericum perforatum), a herbal supplement that can increase serotonin levels
- Have kidney disease (even mild to moderate impairment requires careful monitoring)
- Have a history of seizures (epilepsy) – duloxetine may lower the seizure threshold
- Have a history of mania or bipolar disorder – antidepressants may trigger manic episodes
- Have glaucoma (raised intraocular pressure) – duloxetine may cause mydriasis (pupil dilation)
- Have a history of bleeding disorders or are taking anticoagulants or antiplatelet medications
- Are at risk for low sodium levels (hyponatremia), particularly if you are elderly or taking diuretics
- Are taking other medications that may affect the liver
Contact your doctor immediately if you experience a combination of: restlessness, hallucinations, difficulty coordinating movements, rapid heart rate, elevated body temperature, rapid blood pressure changes, overactive reflexes, diarrhea, nausea, or vomiting. These may be signs of serotonin syndrome, a rare but potentially life-threatening condition that can occur when serotonergic drugs are combined. In its most severe form, serotonin syndrome can resemble neuroleptic malignant syndrome (NMS).
Antidepressant medications, including duloxetine, may increase the risk of suicidal thoughts and behaviour in young adults under the age of 25, particularly during the first few weeks of treatment or when doses are changed. Patients and caregivers should monitor closely for any worsening of depression, unusual changes in behaviour, or emergence of suicidal thoughts. Seek immediate medical attention if these occur. It can be helpful to inform a close friend or family member about your treatment and ask them to alert you if they notice concerning changes.
Children and Adolescents
Duloxetine is generally not recommended for the treatment of depression in children and adolescents under 18 years of age. The risk of side effects including suicidal behaviour, aggression, hostility, and oppositional behaviour is higher in this age group. Additionally, the long-term effects on growth, maturation, and cognitive and behavioural development have not been fully established. However, a doctor may prescribe duloxetine to patients under 18 if they determine the benefits outweigh the risks.
Pregnancy and Breastfeeding
If you are pregnant, planning to become pregnant, or breastfeeding, consult your doctor before using duloxetine. This medication should only be used during pregnancy when the potential benefits clearly justify the potential risks to the fetus.
When SNRI medications are used during pregnancy, particularly in the later stages, there is an increased risk of a condition called persistent pulmonary hypertension of the newborn (PPHN), which causes rapid breathing and a bluish appearance in the baby, usually within 24 hours of birth. Babies exposed to duloxetine late in pregnancy may also experience withdrawal symptoms after birth, including poor muscle tone, trembling, feeding difficulties, breathing problems, and seizures.
Data from clinical use suggest that duloxetine taken during the first three months of pregnancy does not appear to cause an overall increased risk of birth defects. However, use during the second half of pregnancy may increase the risk of preterm birth, with studies suggesting approximately 6 additional premature births per 100 women taking duloxetine during this period, mostly between weeks 35 and 36 of gestation.
If duloxetine is taken near the end of pregnancy, there is also an increased risk of heavy vaginal bleeding shortly after delivery, particularly in women with a history of bleeding disorders. Inform your midwife or doctor that you are taking duloxetine so they can monitor you appropriately.
Duloxetine passes into breast milk. Use during breastfeeding is generally not recommended. Discuss with your doctor to evaluate the benefits of treatment against the potential risks to the infant.
Driving and Operating Machinery
Duloxetine may cause drowsiness, dizziness, or blurred vision. Do not drive or operate heavy machinery until you know how this medication affects you. These effects are most likely to occur during the initial weeks of treatment or when your dose is changed.
How Does Duloxetine Interact with Other Drugs?
Drug interactions can significantly alter the effectiveness and safety of duloxetine. Some interactions may lead to serious, potentially life-threatening adverse effects, while others may reduce the therapeutic benefit of treatment. It is crucial to inform your prescriber about every medication, supplement, and herbal product you are using before starting duloxetine.
Major Interactions
| Drug / Class | Risk | Action Required |
|---|---|---|
| MAO Inhibitors (moclobemide, linezolid, phenelzine, tranylcypromine) | Life-threatening serotonin syndrome or NMS-like reactions | Wait 14 days after stopping MAOI before starting duloxetine; wait 5 days after stopping duloxetine before starting MAOI |
| Fluvoxamine | Potent CYP1A2 inhibitor – dramatically increases duloxetine levels | Contraindicated – do not use together |
| Ciprofloxacin / Enoxacin | Strong CYP1A2 inhibitors – significantly increase duloxetine levels | Contraindicated – do not use together |
| Thioridazine | Duloxetine increases thioridazine levels; risk of serious cardiac arrhythmias | Contraindicated – do not use together |
Moderate Interactions
| Drug / Class | Risk | Action Required |
|---|---|---|
| SSRIs (paroxetine, fluoxetine, sertraline) | Increased risk of serotonin syndrome; paroxetine and fluoxetine also inhibit CYP2D6 | Avoid combination or use with extreme caution; monitor for serotonergic symptoms |
| Triptans (sumatriptan, rizatriptan) | Increased serotonin levels; risk of serotonin syndrome | Use with caution; monitor closely, especially during initiation |
| Tramadol / Pethidine / Buprenorphine | Serotonergic opioids increase risk of serotonin syndrome and seizures | Use with caution; consider alternative analgesics where possible |
| Tricyclic antidepressants (amitriptyline, clomipramine) | Duloxetine inhibits CYP2D6, increasing TCA levels; risk of serotonin syndrome | Avoid combination; if necessary, use reduced TCA doses with monitoring |
| Warfarin and anticoagulants | Increased risk of bleeding; SNRIs affect platelet function | Monitor INR closely when starting, changing dose, or stopping duloxetine |
| Antiplatelet agents (aspirin, clopidogrel) | Increased bleeding risk due to additive effects on platelet function | Use with caution; monitor for signs of bleeding |
| St John's Wort (Hypericum perforatum) | Increased serotonin levels; risk of serotonin syndrome | Avoid concurrent use |
| CNS depressants (benzodiazepines, opioids, antihistamines) | Additive CNS depression; increased sedation, impaired coordination | Use with caution; warn patients about enhanced sedative effects |
Alcohol
Caution is advised when consuming alcohol while taking duloxetine. Both duloxetine and alcohol act on the central nervous system, and their combined use may increase drowsiness, impair coordination, and reduce your ability to drive safely. Furthermore, chronic heavy alcohol use is associated with liver damage, and combining alcohol with duloxetine may increase the risk of hepatotoxicity. There have been rare reports of liver injury, including hepatitis and jaundice, in patients taking duloxetine, particularly those with pre-existing liver risk factors.
What Is the Correct Dosage of Duloxetine?
Always take duloxetine exactly as prescribed by your doctor. The dosage depends on your specific condition, response to treatment, and overall health. Do not change your dose or stop taking duloxetine without first consulting your doctor. The capsules should be swallowed whole with water – do not crush, chew, or open them, as the gastro-resistant coating is designed to protect the medication from stomach acid.
Duloxetine can be taken with or without food, and it is recommended to take it at the same time each day to help maintain consistent blood levels and make it easier to remember.
Adults
| Condition | Starting Dose | Usual Dose | Maximum Dose |
|---|---|---|---|
| Major Depressive Disorder | 60 mg once daily | 60 mg once daily | 120 mg/day |
| Generalized Anxiety Disorder | 30 mg once daily | 60 mg once daily | 120 mg/day |
| Diabetic Neuropathic Pain | 60 mg once daily | 60 mg once daily | 120 mg/day |
For depression and diabetic neuropathic pain, the standard dose is 60 mg once daily. Your doctor may start you on this dose directly or may begin at a lower dose and increase it. For generalized anxiety disorder, treatment commonly begins at 30 mg once daily, with most patients subsequently being increased to 60 mg once daily. In some cases, depending on your response, the dose may be increased up to a maximum of 120 mg daily.
Children and Adolescents
Duloxetine is generally not recommended for the treatment of depression in patients under 18 years of age due to increased risks of suicidal behaviour and other adverse effects (see Warnings section). In some countries, duloxetine may be approved for generalized anxiety disorder in children aged 7 years and older at doses of 30–60 mg daily, but this should only be prescribed under specialist supervision.
Elderly Patients
No specific dose adjustment is routinely recommended for elderly patients based on age alone. However, caution is warranted, as older adults are more susceptible to hyponatremia (low sodium), falls, and drug interactions due to polypharmacy. Renal function should be assessed before initiating treatment, and the starting dose should be as low as clinically appropriate.
Missed Dose
If you forget to take a dose of duloxetine, take it as soon as you remember. However, if it is nearly time for your next scheduled dose, skip the missed dose and take only your regular dose at the usual time. Do not take a double dose to make up for a forgotten one. Never take more duloxetine in a single day than your doctor has prescribed.
Overdose
If you suspect an overdose of duloxetine, seek emergency medical attention immediately by calling your local emergency services or going to the nearest emergency department. Symptoms of overdose may include drowsiness, coma, serotonin syndrome (restlessness, tremors, sweating, fever, muscle rigidity), seizures, vomiting, and rapid heart rate. There is no specific antidote for duloxetine overdose, and treatment is supportive.
What Happens When You Stop Taking Duloxetine?
One of the most important things to understand about duloxetine is that you should not stop taking it suddenly, even if you are feeling better. Abrupt discontinuation of duloxetine can lead to a cluster of withdrawal symptoms known as discontinuation syndrome, which can be very unpleasant and may last from several days to weeks.
When your doctor determines that you no longer need duloxetine, the dose will be gradually reduced over a period of at least two weeks. This tapering process allows your brain to adjust slowly to the decreasing levels of the medication and significantly reduces the risk and severity of withdrawal symptoms.
Patients who abruptly stop duloxetine may experience some or all of the following symptoms:
- Dizziness and vertigo – a sensation of the room spinning or feeling unsteady
- Paraesthesias – tingling, numbness, or electric shock-like sensations, particularly in the head ("brain zaps")
- Sleep disturbances – vivid dreams, nightmares, or insomnia
- Fatigue and drowsiness
- Restlessness, agitation, or anxiety
- Nausea, vomiting, or diarrhoea
- Headache and muscle pain
- Irritability and excessive sweating
These symptoms are typically mild and resolve within a few days to a couple of weeks. However, in some individuals, discontinuation symptoms can be more severe and prolonged. If you experience bothersome symptoms during dose reduction, speak with your doctor – it may be appropriate to reduce the dose more slowly or temporarily increase it before resuming the taper at a gentler pace.
It is also important to understand that continuing to take duloxetine as prescribed, even when you feel well, may be necessary to prevent relapse. Depression and anxiety are chronic conditions, and your doctor will advise you on the appropriate duration of treatment based on your individual circumstances and the number of previous episodes.
What Are the Side Effects of Duloxetine?
Like all medications, duloxetine can cause side effects, although not everyone will experience them. The majority of side effects associated with duloxetine are mild to moderate in severity and tend to diminish as your body adjusts to the medication over the first few weeks of treatment. The following frequency categories are based on data from clinical trials and post-marketing surveillance.
Very Common
Affects more than 1 in 10 people
- Headache
- Drowsiness (somnolence)
- Nausea
- Dry mouth
Common
Affects 1 in 10 to 1 in 100 people
- Decreased appetite and weight loss
- Insomnia, agitation, reduced libido, anxiety, abnormal dreams
- Dizziness, lethargy, tremor, numbness or tingling
- Blurred vision, tinnitus (ringing in the ears)
- Palpitations, raised blood pressure, hot flushes
- Yawning
- Constipation, diarrhoea, abdominal pain, vomiting, heartburn, flatulence
- Increased sweating, itchy rash
- Muscle pain, muscle spasm
- Painful urination, frequent urination
- Erectile dysfunction, ejaculatory difficulties, difficulty reaching orgasm
- Falls (particularly in older adults), fatigue
Uncommon
Affects 1 in 100 to 1 in 1,000 people
- Sore throat, hoarse voice
- Suicidal thoughts, sleep difficulties, teeth grinding, disorientation, lack of motivation
- Involuntary muscle twitching, restless legs syndrome, difficulty controlling movements
- Dilated pupils, visual disturbances
- Rapid or irregular heartbeat, fainting
- Cold fingers and toes, nosebleeds
- Liver inflammation (hepatitis), difficulty swallowing
- Night sweats, hives, increased bruising, sun sensitivity
- Difficulty urinating, decreased urine flow
- Abnormal vaginal bleeding, menstrual changes, testicular pain
- Chest pain, feeling cold, thirst, weight gain
Rare
Affects fewer than 1 in 1,000 people
- Severe allergic reactions (anaphylaxis, angioedema)
- Decreased thyroid function, dehydration, low sodium (SIADH)
- Suicidal behaviour, mania, hallucinations, aggression
- Serotonin syndrome, seizures
- Glaucoma (raised eye pressure)
- Liver failure, jaundice (yellowing of skin and eyes)
- Stevens-Johnson syndrome (severe skin blistering)
- Jaw muscle spasm (trismus)
- Cutaneous vasculitis (inflammation of skin blood vessels)
- Stress cardiomyopathy (Takotsubo syndrome)
- Severe postpartum bleeding
Sexual Dysfunction
Like other SNRI and SSRI medications, duloxetine can cause sexual side effects including reduced libido, erectile dysfunction, delayed ejaculation, and difficulty reaching orgasm. These effects are reported as common side effects in clinical trials. In some cases, sexual dysfunction has persisted after discontinuation of the medication. If sexual side effects are affecting your quality of life, discuss this with your doctor – they may adjust your dose, suggest strategies to manage the symptoms, or consider switching to a different medication.
Contact your doctor or go to the emergency department immediately if you experience: severe allergic reactions (difficulty breathing, swelling of the face, tongue, or throat), signs of liver problems (unexplained nausea, abdominal pain, yellowing of the skin or eyes, dark urine), symptoms of serotonin syndrome (agitation, hallucinations, high fever, muscle rigidity, rapid heartbeat), seizures, or severe skin reactions (widespread blistering of the skin, mouth, or eyes).
How Should You Store Duloxetine?
Proper storage of duloxetine is important to maintain its effectiveness and safety. The medication should be kept in its original packaging to protect it from moisture and light. Store at a temperature not exceeding 25°C (77°F). As with all medications, keep duloxetine out of the sight and reach of children.
Check the expiry date on the carton and blister pack or bottle before taking the medication. The expiry date refers to the last day of the stated month. Do not use duloxetine after this date.
Do not dispose of medications via the toilet or household waste. Return unused or expired duloxetine to your local pharmacy for safe disposal. These measures help protect the environment from pharmaceutical contamination.
What Does Duloxetine Contain?
Each duloxetine capsule contains the active substance duloxetine hydrochloride, equivalent to either 30 mg or 60 mg of duloxetine. The capsules are gastro-resistant, meaning they have a special coating that prevents the medication from dissolving in the acidic environment of the stomach. Instead, the capsule contents are released in the more alkaline conditions of the small intestine, where absorption occurs.
Active Ingredient
Duloxetine (as duloxetine hydrochloride) – 30 mg or 60 mg per capsule.
Inactive Ingredients (Excipients)
The inactive ingredients serve various purposes including protecting the drug, enabling controlled release, and forming the capsule shell:
- Capsule core: Sugar spheres (sucrose and maize starch), hypromellose phthalate, hypromellose, triethyl citrate, hydroxypropyl cellulose, talc
- 30 mg capsule shell: Hypromellose (E464), titanium dioxide (E171), brilliant blue FCF (E133), black iron oxide (E172)
- 60 mg capsule shell: Hypromellose (E464), titanium dioxide (E171), black iron oxide (E172)
- Printing ink: Shellac, propylene glycol, black iron oxide (E172), potassium hydroxide
Duloxetine capsules contain sucrose (sugar) as part of the sugar spheres in the capsule core. If you have been told by your doctor that you have an intolerance to certain sugars, consult your doctor before taking this medication.
Capsule Appearance
Duloxetine is a hard, gastro-resistant capsule. The 30 mg capsule typically has an opaque grey lower half and an opaque blue upper half, marked with "DLX 30". The 60 mg capsule typically has an opaque grey lower half and an opaque white upper half, marked with "DLX 60". Note that the exact appearance may vary between different manufacturers and brand names.
Frequently Asked Questions About Duloxetine
References
This article is based on evidence from the following peer-reviewed sources and international guidelines:
- European Medicines Agency (EMA). Cymbalta (duloxetine) – Summary of Product Characteristics. EMA/CHMP, last updated 2024. Available at: www.ema.europa.eu
- U.S. Food and Drug Administration (FDA). Cymbalta (duloxetine hydrochloride) – Prescribing Information. Reference ID: 5172158. Available at: www.accessdata.fda.gov
- National Institute for Health and Care Excellence (NICE). Depression in adults: treatment and management. NICE guideline [NG222]. Updated 2024. Available at: www.nice.org.uk
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List, 2023. Geneva: WHO; 2023.
- British National Formulary (BNF). Duloxetine monograph. BMJ Group and Pharmaceutical Press. Available at: bnf.nice.org.uk
- Cipriani A, Furukawa TA, Salanti G, et al. Comparative efficacy and acceptability of 21 antidepressant drugs for the acute treatment of adults with major depressive disorder: a systematic review and network meta-analysis. Lancet. 2018;391(10128):1357-1366. doi:10.1016/S0140-6736(17)32802-7
- Lunn MP, Hughes RA, Wiffen PJ. Duloxetine for treating painful neuropathy, chronic pain or fibromyalgia. Cochrane Database of Systematic Reviews. 2014;(1):CD007115. doi:10.1002/14651858.CD007115.pub3
- Warner CH, Bobo W, Warner C, Reid S, Rachal J. Antidepressant discontinuation syndrome. Am Fam Physician. 2006;74(3):449-456.
- American Psychiatric Association. Practice Guideline for the Treatment of Patients with Major Depressive Disorder. 3rd ed. Washington, DC: APA; 2010 (reaffirmed 2023).
- Bandelow B, Michaelis S, Wedekind D. Treatment of anxiety disorders. Dialogues Clin Neurosci. 2017;19(2):93-107. doi:10.31887/DCNS.2017.19.2/bbandelow
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