General Practice 2022

Fluoxetine: what it is for, how to take it and side effects

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Fluoxetine: what it is for, how to take it and side effects
Fluoxetine: what it is for, how to take it and side effects

Fluoxetine is an antidepressant from the selective serotonin reuptake inhibitor class, which acts by inhibiting the uptake of serotonin by neurons, which when low levels can cause depression, panic syndrome, anxiety or obsessive-compulsive symptoms.

This drug is available in pharmacies under the brand name Prozac or in generic form under the name fluoxetine hydrochloride or under the similar names Eufor, Daforin, Fluxene or Verotina, for example, and is sold by prescription only and prescription retention by the pharmacy.

Fluoxetine can be found in the form of 10 mg capsules, 20 mg tablets or as a 20mg/mL solution in drops, administered orally.

What is it for

The main indications for treatment with fluoxetine include depression associated or not with anxiety, bulimia nervosa, obsessive compulsive disorder (OCD), panic syndrome and premenstrual dysphoric disorder which includes PMS, irritability and mood swings.

Fluoxetine can sometimes be used together with another antidepressant, olanzapine, to treat manic depression caused by bipolar disorder. This combination can also be used to treat depression when at least 2 other medications have already been used and the person has not had an improvement in symptoms.

How to take it

Fluoxetine should be taken orally before or after a meal, always at the time instructed by the doctor, preferably taken in the morning or afternoon to avoid insomnia, however if you forget to take a dose at the right time, take it as soon as you remember, but you should skip the missed dose if it is almost time for your next dose.Do not double the dose to make up for the missed dose.

How to use fluoxetine for adults varies by indication and includes:

  • Depression: the maximum recommended dose is 60 mg daily, which can be increased every 2-4 weeks;
  • Bulimia nervosa: the dose is 60 mg orally once daily;
  • Obsessive compulsive disorder: the recommended starting dose is 20 mg daily, which can be increased after a few weeks to a maximum of 60 mg daily;
  • Panic syndrome: The recommended dose is 10 mg orally once daily in the morning, and may be increased to 20 mg once daily after a week of treatment. The maximum dose should not exceed 60 mg per day divided into two doses in the morning and in the afternoon;
  • Premenstrual dysphoric disorder: The starting dose is 20 mg orally once daily taken continuously, which can be divided into two doses in the morning and in the afternoon.Another form of use is the dose of 20 mg per day, starting 14 days before menstruation, interrupting use on the first day of menstruation and repeating this form of use every month.

Fluoxetine may take up to 4 weeks of treatment to have the desired effect and increasing doses should only be done according to the physician's evaluation and guidance.

Possible side effects

Some of the most common side effects that may occur during treatment with fluoxetine are insomnia, headache, dizziness, drowsiness, tiredness, changes in vision, tremors, feeling anxious or nervous, stomach pain, loss of appetite, nausea, vomiting, diarrhea, dry mouth, excessive sweating, hot flashes, weight changes, decreased sexual desire or impotence.

It is advised to discontinue use and seek medical help immediately or the nearest emergency department if fluoxetine allergy symptoms such as difficulty breathing, feeling of a closed throat, swelling of the mouth, tongue or face, hives, fever, burning sensation in the eyes, pain or blistering of the skin or peeling.Learn more about allergic reaction symptoms.

In addition, the doctor should be reported if the person has mood or behavior changes, anxiety, panic attacks, difficulty sleeping or impulsiveness, irritation, agitation, aggression, depression or thoughts of suicide.

Fluoxetine lose weight?

Fluoxetine may help with weight loss due to its appetite loss side effect, which could be a weight loss benefit in people who are obese or overweight. However, the exact mechanism of how fluoxetine contributes to weight loss is not completely understood and, therefore, its use is not indicated in the treatment of obesity. Learn more about using fluoxetine for weight loss.

Who should not take it

Fluoxetine should not be used by children, pregnant or breastfeeding women, or by people using monoamine oxidase inhibitor (MAOI) medications such as isocarboxazid (Marplan), phenelzine (Nardil) or tranylcypromine (Parnate), waiting at least 14 days after stopping treatment with monoamine oxidase inhibitors before starting treatment with fluoxetine.

Furthermore, fluoxetine may interfere with the action of other drugs such as:

  • Anxiety medications like alprazolam, diazepam, chlordiazepoxide;
  • Drugs for depression such as imipramine, desipramine or lithium;
  • Epileptic medication such as phenytoin or carbamazepine;
  • Drugs for schizophrenia or psychosis such as clozapine or haloperidol.

It is important to inform the doctor and pharmacist of all medicines or natural products that are used, such as tryptophan or St. John's wort supplementation, to avoid increasing the effect of fluoxetine and the appearance of side effects.

Furthermore, during treatment with fluoxetine, alcohol should be avoided as it may increase side effects, especially drowsiness and dizziness.

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