IRFANA PARVEEN
By Irfana Parveen

B.Sc (Psychiatry Ward)

23 November 2021
Medically reviewed by
Sumayya Salam
Pharm D
Fluoxetine Vs Duloxetine
Table of Contents

Antidepressants have FDA approval as treatments for different medical conditions, yet they may be the preferred medication for depression. In general, antidepressants fall into two categories: serotonin-norepinephrine reuptake inhibitors (SNRIs) and selective serotonin reuptake inhibitors (SSRIs).

Duloxetine and fluoxetine are medications used to treat major depression and anxiety disorders. Doctors give both medications for both short- and long-term use. Duloxetine and fluoxetine work in the brain in various ways, even though their effects are identical. Fluoxetine is an SSRI (selective serotonin reuptake inhibitor), whereas duloxetine is an SNRI (serotonin-norepinephrine reuptake inhibitor).
 
Let us find out how these two drugs treat common mental health conditions and how they differ from one another. To know further continue reading.

What Is Fluoxetine?

Fluoxetine is prescribed to treat depression, obsessive-compulsive disorder, some eating disorders, and panic attacks. Fluoxetine is also used to relieve the symptoms of premenstrual dysphoric disorder, including mood swings, irritability, bloating, and breast tenderness.

What Is Duloxetine?

Duloxetine treats depression in adults and generalized anxiety disorder in adults and children seven years of age and older. Duloxetine is also used to treat pain and tingling caused because of diabetic neuropathy in adults and fibromyalgia in adults and children 13 years of age and older. It is also used to treat ongoing bone or muscle pain, such as lower back pain or osteoarthritis in adults.

How Does Fluoxetine Work?

It can also be used along with olanzapine to treat depression that did not respond to other medications and episodes of depression in people with bipolar disorder.  

Fluoxetine is in a class of medications called selective serotonin reuptake inhibitors (SSRIs). It works by increasing the amount of serotonin, a natural substance in the brain that helps maintain mental balance. Fluoxetine inhibits the reuptake transporter protein present in the presynaptic terminal and thus prevents serotonin from entering presynaptic serotonin neurons. Fluoxetine has a negligible effect on 5HT2A and 5HT2C receptors as well.

Fluoxetine's influence on noradrenergic reuptake is minimal. It has an activating impact since it reuptakes serotonin, and because of its long half-life, the initial antidepressant action starts to take effect within two to four weeks.

How Does Duloxetine Work?

Duloxetine is in a class of medications called selective serotonin and norepinephrine reuptake inhibitors (SNRIs). It works by increasing the amounts of serotonin and norepinephrine, natural substances in the brain that help maintain mental balance and stop the movement of pain signals in the brain. The blockage of norepinephrine transporters is the mechanism of action for the rise in dopamine levels. 

You need a prescription to buy duloxetine online from a certified pharmacy, as it is not available over the counter. 

How Is Fluoxetine Different From Duloxetine?

Both fluoxetine and duloxetine are medications used to treat major depression and anxiety disorders. But fluoxetine and duloxetine work in the brain in different ways. Fluoxetine is a selective serotonin reuptake inhibitor (SSRI), while Duloxetine is a serotonin-norepinephrine reuptake inhibitor (SNRI).

Fluoxetine primarily affects serotonin and is typically used for mood disorders. It may treat various mood disorders than duloxetine, including bipolar disorder.

Duloxetine works on serotonin and norepinephrine, so it has applications in treating some issues where fluoxetine wouldn’t work. It includes issues like nerve pain and fibromyalgia. 

When Fluoxetine and Duloxetine are combined, it can increase your risk of developing serotonin syndrome. The symptoms include confusion, hallucinations, seizures, etc.
Sertraline, an antidepressant that doctors commonly prescribe, appears to work by reducing anxiety first and doesn't start tackling depressive symptoms until weeks later.
The most frequent side effects of fluoxetine are nausea, insomnia, and anxiety. These usually become better with time for many people. Medications like Fluoxetine might have sexual side effects.
Duloxetine is a member of the class of medications known as selective norepinephrine reuptake inhibitors (SNRIs). The drug is not a narcotic or an SSRI (selective serotonin reuptake inhibitor).

Dosage Of Fluoxetine And Duloxetine 

A perfect dosage helps the person to get relief from the conditions. It is necessary to follow the doctor's dosage advice so that you would not get into any trouble. Before consuming medicine, it is necessary to read the leaflet of the medicine for consumption of the medicine.

Fluoxetine 

Fluoxetine may be taken with or without food. Fluoxetine (Prozac) capsules, tablets, and liquid are usually taken once a day in the morning or twice a day, in the morning and at noon. Fluoxetine delayed-release capsules are generally taken once a week.

Fluoxetine (Sarafem) is usually taken once a day, either every day of the month or on certain days of the month. It may take 4 to 5 weeks or longer before you feel the full benefit of fluoxetine. You can also buy Fluoxetine online from a certified online pharmacy, but it is recommended to get a doctor's prescription first. 

Duloxetine 

Take once or twice a day with or without food. When duloxetine is used to treat generalized anxiety disorder, the pain of diabetic neuropathy, fibromyalgia, or ongoing bone or muscle pain, it is usually taken once a day with or without food. Take duloxetine at around the same time(s) every day. Duloxetine may help control your symptoms but will not cure your condition.

Which Is More Effective?

Compared to Fluoxetine, Duloxetine produces better clinical results regarding depression severity and increased functioning. It has a better adverse effect profile. Due to its dual mechanism, duloxetine is 4.5 times more efficient and acts faster than SSRIs.

Additionally, compared to other dual-action antidepressants like venlafaxine, duloxetine appears to be a more equally distributed inhibitor of serotonin and norepinephrine reuptake.

Study related to Fluoxetine vs Duloxetine

A study by Ravinder Kumar Sah included sixty-six patients, aged 18 to 65, of either sex, with Major Depressive Disorder on an outpatient basis and met ICD-10 DCR criteria. Fluoxetine 20–60 mg/day and duloxetine 40–60 mg/day were randomly assigned to each patient's group. During the 16-week study, the patients took both study medicines daily, and their dosage was adjusted based on their needs. 

Due to its combined effects on the serotonin and norepinephrine systems, duloxetine was more effective than SSRIs in the current 16-week research and earlier short-term investigations.  

Side Effects Of Fluoxetine and Duloxetine

Side effects lead to negative effects. To not fall into such, you should know the effects that you might affect with. Common effects can be cured as time passes, but you must look over the severe effects. Contact your doctor if you are suffering from any of the severe effects.

Fluoxetine

Common Side Effects

Severe Side Effects 

Nervousness

Rashes

Anxiety

Hives or blisters

Difficulty falling asleep or staying asleep

Itching

Nausea

Fever

Diarrhea

Joint pain

Duloxetine

Common Side Effects 

Serious Side Effects

Unusual bruising or bleeding

Unusual bruising or bleeding

Nausea or vomiting

Swelling of the abdomen

Diarrhea

Itching

Acid Reflux or Heat Burn

Yellowing of the skin or eyes

Dry mouth

Loss of appetite

Warnings For Fluoxetine And Duloxetine Usage

Young adults up to 24 years of age who took fluoxetine during clinical studies became suicidal or thought about harming themselves or planning or trying to do so.

Children, teenagers, and young adults who take fluoxetine to treat depression or other mental illnesses may be more likely to become suicidal than those who do not take any antidepressants to treat these conditions.

However, experts are not sure how big this risk is and how it should be considered in deciding whether a child or teenager should take an antidepressant. 

Precautions of Fluoxetine and Duloxetine

Considering precautions will help you not get affected by any side effects. Precautions are indeed needed while you consume any medicine. The working of the medicine will be smooth in the body and not cause any problems. It will be helpful if you inform your health conditions to your doctor.

Fluoxetine

  • If any of the following apply to you, let your doctor know:
  1. epilepsy
  2. maniac episodes in the past; 
  3. diabetes; 
  4. liver issues
  5. Heart conditions
  • You may take this medication with or without food. 
  • Refrain from alcohol use while using this medication.
  •  Before using this medication, tell your doctor or pharmacist if you are pregnant, nursing, or planning a pregnancy.
  • Fluoxetine passes into breast milk. It can have adverse effects on infants.
  • Do not operate machinery or vehicle when you are on this drug.
  • Take a dose as soon as you remember if you forget to take one. Do not take the missed dose if it is almost time for your next dose. Do not take a second dose for the missed one.
  • Never stop taking Fluoxetine without first consulting your doctor.

Duloxetine

  • Inform patients, their families, and their caregivers to be alert for the onset of suicidal ideation and behavior, and notify their healthcare practitioner of such signs.
  • Duloxetine should be consumed whole; do not chew or crush.
  • Avoid using alcohol while on this medication.
  • Let your doctor know if you are pregnant or intend to do so while taking duloxetine. 
  • If you are breastfeeding, let your doctor know as well. Duloxetine passes into breast milk. 
  • Duloxetine may cause dizziness and sedation. Therefore, advise patients to avoid operating potentially dangerous equipment and vehicles.

Bottom Line From Practical Anxiety Solutions

Although antidepressants are useful for treating depression and its associated symptoms, many people may not receive the proper care. To manage depression effectively, a clinician must use an interprofessional team-centred strategy to educate patients, use evidence-based medication, closely monitor compliance, identify side effects, and assess treatment effectiveness.

Fluoxetine and Duloxetine, one an SSRI and the other an SNRI—are both recommended to treat depression. Duloxetine outperforms Fluoxetine in terms of clinical outcomes for depression severity and improved functioning. One could be favoured over the other due to its different uses. The condition that the person  is suffering will determine the outcome.

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