Fluoxetine is an antidepressant used in the treatment of depression, anxiety, bulimia nervosa, and obsessive compulsive disorder. It works by inhibiting the reuptake of the neurotransmitter serotonin, allowing for higher levels of serotonin in the brain.

Fluoxetine is a prescription medication that can be found at most pharmacies and drug stores. It comes in capsules, pills, and a liquid form, and is sold as the generic fluoxetine or under the brand name Prozac, among others.

What it's used for

Fluoxetine is indicated for the treatment of:

Depression, with or without anxiety;
Bulimia nervosa;
Obsessive compulsive disorder (OCD);
Premenstrual dysphoric disorder (PMDD), which includes PMS, irritability, and mood swings. Read about PMS symptoms.

Fluoxetine may sometimes be used in combination with olanzapine, another antidepressant, in the treatment of bipolar depression.

This combination can also be used to treat depression that does not respond to treatment with at least two other medications.

Fluoxetine should only be taken under a doctor's supervision in order to evaluate response to treatment and the presence of any side effects.

Learn mores about depression symptoms.

Recommended dosing

Fluoxetine is taken by mouth, with a full glass of water, before or after meals, preferably in the morning or afternoon to avoid insomnia.

The usual dose for adults varies based on indication:

Depression: typical dose is 20 mg daily;
Bulimia nervosa: recommended dose is 60 mg daily;
Obsessive compulsive disorder: recommended starting dose is 20 mg daily and may be gradually increased up to a maximum dose of 60 mg per day;
Premenstrual dysphoric disorder: starting dose is 20 mg once daily taken every day. Another option is to take 20 mg daily beginning 14 days prior to menstruation and discontinuing use on the first day of your period. This scheduled is then repeated monthly.

Dosing and length of treatment with fluoxetine should always be determined by a doctor. Do not change the dose or stop taking fluoxetine without consulting your doctor or prescribing provider.

Time to take effect

It can take up to 4 weeks for fluoxetine to achieve its desired effect and the dose should only be increased after consultation with your doctor.

Side effects

The most common side effects of fluoxetine are insomnia, headache, dizziness, drowsiness, fatigue, vision changes, tremors, anxiety or nervousness, abdominal pain, nausea, vomiting, dry mouth, excessive sweating, hot flashes, weight changes, decreased libido, and impotence.

Some people may experience an allergic reaction to fluoxetine. It is important to seek emergency medical attention for symptoms such as difficulty breathing, throat closing, hives, or swelling of the mouth, tongue, or face.

Make sure to tell your doctor right away if you experience changes in mood or behavior, anxiety, panic attacks, difficulty sleeping, impulsivity, irritability, agitation, aggression, worsening depression, or thoughts of suicide.

Weight loss

Loss of appetite is a possible side effect of fluoxetine, which may lead to weight loss. This could be an additional benefit to people with overweight or obesity who are taking fluoxetine.

Fluoxetine is not approved for treatment of obesity, however, as the mechanism in which fluoxetine contributes to weight loss is not entirely clear.

Contraindications to use

Before taking fluoxetine, make sure to tell your doctor if you are pregnant or breastfeeding. Fluoxetine may not be approved for use in all children, so talk to your pediatrician to make sure it is right for your child.

Fluoxetine can interfere with other medications such as:

Medications for anxiety such as alprazolam, diazepam, and chlordiazepoxide;
Medications for depression such as imipramine, desipramine, and lithium;
Medications for epilepsy such as phenytoin and carbamazepine;
Medications for schizophrenia and psychosis such as clozapine and haloperidol.

Fluoxetine is contraindicated in people taking monoamine oxidase inhibitors (MAOIs) such as isocarboxazid, phenelzine, and tranylcypromine. MAOIs should be discontinued for at least 14 days prior to starting fluoxetine.

Tell your doctor about any medications or natural remedies you may be taking, as supplements like tryptophan or St John's wort can increase the effects of fluoxetine as well as the risk of side effects.

It is advised to avoid drinking alcohol while taking fluoxetine, as alcohol can increase the risk for side effects such as drowsiness and dizziness.