Prozac is an antidepressant. It is mainly used to treat major depression, obsessive-compulsive disorder, and panic disorder.

Also known by its generic name, fluoxetine, Prozac is a selective serotonin reuptake inhibitor (SSRI). Around 1 in 10 people in the United States (U.S.) are thought to use SSRI drugs, and 1 in 4 women in their 40s and 50s.

Prozac first appeared in the U.S. in 1988 and it became one of the most widely prescribed antidepressants in the country. It remains popular, although newer drugs are now available, such as sertraline and citalopram.

It is available as a liquid, tablet, capsule, and as a delayed-release, long-acting capsule. It is suitable for adults and it can be used in some cases for children over the age of 10 years.

Fast facts on Prozac:

Here are some key points about Prozac. More detail is in the main article.

  • Prozac, or fluoxetine, is a selective serotonin reuptake inhibitor (SSRI) and a widely used antidepressant.
  • It is considered safe and effective in treating depression, anxiety, and obsessive compulsive disorder (OCD), and bulimia.
  • Adverse effects include an increased risk of suicidal thoughts in some younger people.
  • It should not be used with monoamine oxidase inhibitors (MAOIs) and some other drugs.
  • Anyone who wishes to stop using Prozac should do so gradually, with a doctor's help, to prevent adverse reactions.

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Prozac can help treat depression, but it may have adverse effects.

Antidepressants, including Prozac, can have a number of possible adverse effects.

The FDA requires Prozac to come with a black box warning stating that antidepressants may increase the risk of suicide in people younger than 25 years. It can lead to suicidal thoughts, or a worsening of these, in children and young adults.

Other possible side effects include:

  • decreased libido and sexual dysfunction
  • anxiety and nervousness
  • abnormal dreams
  • sweating
  • diarrhea
  • asthenia, or lack of bodily strength
  • skin rash
  • tremor
  • flu syndrome
  • insomnia, drowsiness, and yawning
  • sinusitis, an inflammation of the mucous membrane
  • painful or difficult digestion, known as dyspepsia
  • dry mouth
  • nausea
  • vasodilatation, or widening of the blood vessels

Drug-drug interactions

The manufacturers warn that Prozac should not be taken together with:

  • monoamine oxidase inhibitors (MAOIs): Pimozide and Thioridazine
  • drugs metabolized by CYP2D6
  • tricyclic antidepressants (TCAs)

Care should be taken when used with drugs that affect the central nervous system (CNS), such as those belonging to the "benzodiazepines" class of drugs. Examples include Diazepam and Lorazepam.

It should be used with care with non-steroidal anti-inflammatories (NSAIDs), aspirin, warfarin and other drugs that affect blood coagulation, as there is a risk that it could lead to bleeding.

Prozac should not be used with antipsychotics, other SSRIs and other serotonergic agents, including lithium and St. John's Wort.

There is also a chance that fluoxetine may activate mania in a person who is susceptible.

Pregnancy and breastfeeding

Women should only take Prozac during pregnancy if the potential benefits outweigh the possible risks to the fetus.

Studies have found that antidepressants increase the risk of neonatal maladaptation syndrome. Symptoms include jitteriness, problems with feeding and breathing, and hypoglycemia, or low blood sugar.

Breastfeeding is not advised, as fluoxetine can pass into the milk.

As with any drug, there is also a chance that a person may be allergic to the ingredients. If the patient experiences a rash, hives, swelling, or difficulty breathing, they should contact a doctor, as an allergic reaction can become a medical emergency.

Dosage depends on the age of the patient and the purpose of treatment. Here are some examples of doses.

The normal adult dose for depression starts with 20 milligrams (mg) a day, taken by mouth, in the morning. It can be increased if symptoms do not improve after a few weeks. The maintenance dose is from 20 to 60 mg a day, and the maximum dose is 80 mg a day.

An adult who uses delayed release oral capsule to treat depression will take a 90 mg capsule once a week.

It may take 4 weeks or more to see any effects.

Each patient must follow their doctor's advice on how much to take, how often, and when.

Taking the wrong dose can be dangerous.

Patients who suddenly reduce their dose or stop taking Prozac may experience a number of unwanted effects.

These include:

  • brain zaps
  • dizziness
  • confusion
  • nightmares and insomnia
  • vertigo
  • nausea
  • tremor
  • gastrointestinal problems
  • flu-like symptoms
  • anxiety or agitation
  • spells of weeping
  • irritability
  • aggressiveness

Suddenly stopping an antidepressant that has been used for 6 weeks or more can lead to withdrawal syndrome. Reducing intake can sometimes have this effect.

These effects can normally be minimized by stopping use over at least 4 weeks.

Some patients do not experience withdrawal symptoms, while others will experience symptoms if they stop over several weeks. Some patients may need to stop suddenly, for example, due to adverse effects or pregnancy. It is important for the patient and their doctor to discuss how to stop using fluoxetine.

Prozac is selective serotonin reuptake inhibitor (SSRI). It works by blocking the absorption of the neurotransmitter serotonin in the brain.

Regulating the amount of serotonin helps brain cells transmit messages to each other. This results in a better and more stable mood. It also results in more neurons being present in a region of the brain called the "dentate gyrus," part of the hippocampal formation. The hippocampus plays a role in forming memories.

The U.S. Food and Drug Administration (FDA) currently approves Prozac for acute and maintenance treatment of major depressive disorder (MDD), obsessive compulsive disorder (OCD), bulimia nervosa, and panic disorder, with or without agoraphobia.

Prozac is normally used alone. However, fluoxetine combined with olanzapine (OFC) can also be used to treat depressive episodes in people with bipolar disorder. Fluoxetine combined with olanzapine is known as Symbyax. This combination can also help people with treatment-resistant depression.

Some doctors may prescribe Prozac "off-label" to treat anxiety, premature ejaculation, obesity, and binge-eating disorder.

Depression

Prozac can be used to treat depression in adults. It can also be used for children and adolescents from the age of 10 to 19 years with severe, persistent depression. However, the National Institute of Mental Health (NIMH) urge caution, as a small subset of adolescents have shown suicidal tendencies after using it.

A review comparing the effectiveness of Prozac with other antidepressants found that it appears to be similarly effective, and possibly better tolerated. However, the authors concluded that more research is needed, as a number of factors made an exact comparison difficult.

Findings reported in Progress in Neuro-Psychopharmacology and Biological Psychiatry have suggested that some patients' depression does not respond to treatment with the SSRIs paroxetine (Paxil) and citalopram (Celexa), because of a specific genetic factor. These patients, say the researchers, may benefit from a switch to Prozac.

Panic disorder

A number of studies have suggested that Prozac can reduce the incidence of panic attacks in people with panic disorder.

In one study, around 7 percent of patients reported experiencing increased anxiety in the first few weeks after they started using Prozac, compared with 9 percent who took a placebo. However, compared with the overall benefits, this is considered small enough that Prozac is still "safe and effective" as a treatment for anxiety and panic attacks.

Obsessive-compulsive disorder (OCD)

SSRIs normally need to be taken for at least 11 weeks before a person with OCD experiences any benefits. Patients with OCD normally use an SSRI such as Prozac for at least a year, depending on the individual's needs and situation.

A study published in the Journal of the American Academy of Child and Adolescent Psychiatry, concluded that a 20 to 60 milligram (mg) dose of fluoxetine was effective in treating children and adolescents with OCD. Participants also tolerated the drug well.

Bulimia nervosa

Researchers reported in The American Journal of Psychiatry that for patients with bulimia nervosa who had not responded to psychological treatment, fluoxetine may be a useful intervention. It may provide benefits for bulimia if it is taken for up to a year.