Fluoxetine Dosage (A brief Guide)


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Page last updated: 15/10/2022

Fluoxetine Dosage

In this blog post about Fluoxetine Dosage, we will also discuss what fluoxetine is, side effects and what happens if someone overdoses. 

Fluoxetine: What is it?

Fluoxetine belongs to the Selective Serotonin Reuptake Inhibitors (SSRIs) group of antidepressants and it is considered very effective when treating depression.

However, when compared to citalopram, it seems to have a slower reaction time. 

Unlike Citalopram, Fluoxetine is also used when treating other disorders such as bulimia, obsessive-compulsive disorder (OCD), panic disorder and premenstrual dysphoric disorder (PMDD).

Antidepressants are drugs prescribed to treat mental disorders. Some of the most common are:

  • Anxiety disorders
  • Phobias
  • Bulimia
  • Some medical conditions

How do Antidepressants work?

Antidepressants act in your body by prolonging or boosting the activity of neurochemicals such as noradrenaline and serotonin, which are thought to be involved in mood regulation. 

There are several different types of antidepressants, and they are:

  • selective serotonin reuptake inhibitors (SSRIs)
  • serotonin and noradrenaline reuptake inhibitors (SNRIs)
  • tricyclics and tricyclic-related drugs
  • monoamine oxidase inhibitors (MAOIs) 
  • other antidepressants

How should I take Fluoxetine?

You can take it with or without food. Oral tablets are available at 10 mg, 20 mg or 40 mg. It is available  in capsules, tablets, capsules with delayed-release and oral solution

Also, it can take 4-6 days for you to start seeing some improvement long term and 1-3 days short term.

Remember, You should always follow your doctor’s instructions at all times.  

Fluoxetine Dosage (A brief Guide)

Fluoxetine Dosage

According to the National Institute for Health and Care Excellence (NICE) the dosages are recommended as follows:

Major depression

How: by mouth

Fluoxetine Dosage for Adults:

The initial dose is 20 mg a day. The dose is increased after being assessed 3 to 4 weeks later and intervals thereafter.

The daily dose may be administered as a single or divided dose. The maximum recommended is 60 mg per day.

Fluoxetine Dosage for the Elderly:

Same as in a regular adult dosage, Initially 20 mg daily. The dose is increased after being assessed 3 to 4 weeks later and intervals thereafter.

The daily dose may be administered as a single or divided dose. The maximum recommended dose is 40 mg a day but doses up to 60 mg daily can be used.

Bulimia nervosa

How: by mouth

Dosage for Adults

Recommended: 60 mg a daily and it may be administered as a single or divided dose.

For Elderly

Recommended: Up to 40 mg daily and the daily dose may be administered as a single or divided dose.

Usually, the maximum dose a day is 40 mg but doses up to 60 mg daily can be used.

Fluoxetine Dosage (A brief Guide)

Obsessive-compulsive disorder

How: by mouth

Dosage for Adults

Recommended: 60 mg a daily and it may be administered as a single or divided dose.

Recommended: 20 mg a day, increased if necessary up to 60 mg a day.  The daily dose may be administered as a single or divided dose.

The dose can get increased gradually and if the treatment seems to be inadequate after 10 weeks then the dose gets increased to 60 mg a day.

Attention: these are just referenced dosages from NICE.

Don’t stop your medication or change the intake unless your doctor instructs you to. 

Fluoxetine: Side effects

Some of the most common and known side effects of fluoxetine are according to RxList are:

  • Nausea,
  • Upset stomach,
  • Constipation,
  • Headaches,
  • Anxiety,
  • Sleep problems (insomnia),
  • Drowsiness,
  • Dizziness,
  • Nervousness,
  • Heart palpitations,
  • Loss of appetite or increase in appetite,
  • Weight changes
  • Cold symptoms (stuffy nose, sneezing, sore throat),
  • Dry mouth,
  • Decreased sex drive,
  • Impotence
  • Difficulty having a sexual release

Fluoxetine Drug interactions

Fluoxetine may interact with medicines meant for cold or allergies, sedatives, narcotics, pain killers, sleeping pills, muscle relaxers, medicine for seizures or anti-anxiety medication, monoamine oxidase inhibitors (MAOIs), nonsteroidal anti-inflammatory drugs (NSAIDs), other antidepressants or medicine for migraine. 

Other drugs 

  • Alprazolam
  • Clopidrogel
  • Clozapine
  • Flecainide
  • Haloperidol
  • Nebivolol
  • Vinblastine
  • Seizure medications

Fluoxetine Overdose

If you think you or someone else has taken a fluoxetine overdose you should get in contact with medical emergency services. 

Some of the most common symptoms of a Fluoxetine overdose are:

  • Feeling confused
  • Being unresponsive
  • Shaking uncontrollably
  • Feeling dizzy
  • Irregular or very fast heartbeat
  • Hallucinations
  • Restlessness
  • Having fever
  • Fainting
  • Losing consciousness

Possible complications after an overdose

A fluoxetine overdose can come with medical complications such as seizures, abnormal heart rhythm, kidney failure and respiratory. 

Benefits of Fluoxetine Dosage

According to Drugs.com some of the benefits of Fluoxetine are described as follows:

  • Fluoxetine may be used in the treatment of depression and it can help maintain the relief of depression in adults and children (8 -18 years).
  • Fluoxetine may be helpful for the relief of the obsessive-compulsive symptoms in adults and children (7-17 yeats).  
  • Fluoxetine may be helpful in the treatment of eating disorders like bulimia nervosa, relieve the symptoms (moderate to severe) such as binge-eating and vomiting.
  • Fluoxetine may be helpful in the treatment of panic disorders in adults (with/without agoraphobia).
  • Fluoxetine may be helpful in treating premenstrual dysphoric disorder or PMDD. 
  • Fluoxetine is less likely to cause weight gain in comparison to other antidepressants, but it can cause insomnia.

Fluoxetine Dosage (A brief Guide)

Negative aspects of fluoxetine dosage

According to Drugs.com some of the negative aspects of Fluoxetine are described as follows:

  • Cab cause anxiety, fatigue or lack of energy, drowsiness or insomnia, diarrhoea, indigestion, among others specified as side effects. 
  • As with other antidepressants, taking fluoxetine increases the chance of suicidal thoughts and behaviour.
  • Taking fluoxetine can cause drowsiness and impair your judgement or affect your driving abilities. 
  • Interaction with other drugs or overdosage can result in serotonin syndrome (includes symptoms such as agitation, hallucinations, coma and delirium), higher fast rate, feeling dizzy, flushed, shaky and muscle rigidity. 
  • Another syndrome caused by interaction with other drugs or substances is the neuroleptic malignant syndrome. Symptoms for this syndrome include high body temperature, muscle rigidity and psychological disturbances. 
  • Increases the risk of bleeding, especially if it is used with other drugs that also may increase bleeding. 
  • Can precipitate manic episodes if the person taking fluoxetine has undiagnosed bipolar disorder.
  •  May cause withdrawal symptoms if medication intake is stopped suddenly. 

Antidepressants: Suicidal Risk

Some studies have shown that taking antidepressants is associated with a higher risk of suicidal behavior (suicidal thinking or attempts) when compared to placebo drugs.

This risk has been associated with age in the case in children, adolescents, and adults with major depressive disorder (MDD) or related psychiatric disorders. 

One study conducted by the Centre for Suicide Research in Oxford, England attempted to identify which antidepressant drugs were more closely related to suicides or suicide attempts using coroner reports and hospital admissions from six hospitals across the United Kingdom and Wales (between 2000 and 2006). 

They found that Tricyclic antidepressants or TCAs had the highest toxicity and rate of fatality compared to other classes of antidepressants.

Additionally from the SSRIs group, Citalopram indicated to be the one with the highest toxicity and fatality rates. 

Besides being a treatment often used for depression, it can also be prescribed for the treatment of other major psychiatric disorders such as Obsessive-compulsive disorder (ODD), Panic disorder, premenstrual dysphoric syndrome (PMDD), anxiety disorders, post-traumatic stress disorder (PTSD) and eating disorders. 

People under antidepressant medication should always be monitored and observed closely to help reduce or prevent suicidal behavior.  

Why is this blog post about Fluoxetine dosage important?

This blog about fluoxetine dosage is important because it helps understand what fluoxetine is, how it works, side effects, overdose symptoms and course of action and benefits and negative aspects of taking this medicine. 

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