Prozac (Fluoxetine) vs. Lexapro (Escitalopram)

Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.

Alex Yampolsky, PharmD, is a clinical pharmacist at Elizabeth Seton Children's Center, a pediatric long-term care facility in Yonkers, New York.

When looking to treat depression or other commonly diagnosed mental health conditions, your healthcare provider may prescribe Prozac or Lexapro.

While the two drugs may sound familiar or interchangeable, they contain some key differences.

Prozac (fluoxetine) and Lexapro (escitalopram) are Food and Drug Administration (FDA)-approved prescription drugs for major depressive disorder (MDD), commonly known as depression).

Prozac and Lexapro are in a class of antidepressant drugs called selective serotonin reuptake inhibitors (SSRIs). They work by increasing levels of serotonin in the brain.

Prozac contains the active ingredient fluoxetine, and Lexapro includes the active ingredient escitalopram.

Prescribed for more than depression, both drugs treat other mood disorders, such as anxiety.

This article will compare Prozac and Lexapro, including their specific indications, side effects, warnings, standard dosages, and other important information.

While Prozac and Lexapro are similar, they share some significant differences.

Prozac and Lexapro, as SSRI antidepressants, work the same way:

Serotonin is usually reabsorbed by nerve cells in the brain. SSRIs block this absorption, increasing serotonin levels in the brain.

Serotonin is a chemical messenger called a neurotransmitter. It involves mood, sleep, appetite, memory, social behavior, and sexual desire.

Prozac and Lexapro are in the same drug class and work similarly but differ slightly in their indications (uses).

Prozac is FDA-approved to treat:

Prozac is sometimes prescribed off-label (for an un FDA-approved use). Some examples of off-label Prozac use include:

Lexapro is FDA-approved to treat:

Lexapro is sometimes prescribed off-label. Some examples of off-label Lexapro use include:

Together, fluoxetine and olanzapine are available as a combination medication under Symbyax.

Symbyax can treat depressive episodes associated with bipolar I disorder and treatment-resistant depression.

Prozac is eliminated from the body slower than all other SSRIs, including Lexapro.

However, it's important to note that either antidepressant can take up to several weeks to start working and up to several months to see the full effect.

Prozac and Lexapro are both SSRIs (antidepressants), and both are used to treat depression.

Prozac is sometimes used off-label for anxiety, while Lexapro is FDA-approved to treat anxiety. Each drug has various uses and off-label uses.

SSRIs like Prozac or Lexapro are often used as a first treatment choice for depression. This is because they are considered to be safe and effective. They are also better tolerated than certain other types of antidepressants.

However, some recent studies reviewed the two drugs to determine whether one is more effective.

A recent article published in American Family Physician reviewed guidelines from the United States Department of Veterans Affairs and Department of Defense (Va/DoD), the American Psychological Association (APA), and the American College of Physicians (ACP), which are widely referred to in the treatment of depression.

The authors state that the best available evidence cannot establish superiority among various antidepressants, including SSRIs. The only consistent finding is that each antidepressant is more effective than a placebo (an inactive pill that contains no active drug).

The authors also recommend that because no antidepressant is superior, it is reasonable to prescribe a medication based on anticipated adverse effects and individual preference.

The authors also reiterate the VA/DoD guidelines that antidepressant medication should be used for at least six months.

Another recent study compared the SSRIs Prozac, Lexapro, and Zoloft (sertraline) and found all three medications effectively improved depression symptoms.

The authors note that in deciding which antidepressant to prescribe, the healthcare provider will consider the medicine's effectiveness, individual preference, and potential side effects.

To determine which medicine is best for an individual, the healthcare provider will consider all the information, including the person's age, medical history, symptoms/diagnosis, dosing, potential side effects, cost, and insurance coverage.

Prozac or Lexapro have similar contraindications (conditions where it is unsafe to take the medication).

Before taking Prozac or Lexapro, tell your healthcare provider about your medical conditions, medical history, and family history.

You should not take Prozac or Lexapro if allergic to fluoxetine, escitalopram, Celexa (citalopram), other SSRIs, or inactive ingredients in Prozac or Lexapro.

Other people who should not take Prozac or Lexapro include people who have taken a drug in the monoamine oxidase inhibitor (MAOI) drug class in the past 14 days.

Prozac or Lexapro may be prescribed cautiously in some people only if the healthcare provider determines it is safe.

Specifically, this includes individuals under 25 years old, older adults, people who consume alcohol, and people who take medications that cause a slowing of the central nervous system (CNS, such as anxiety, sleep, or pain medication).

Also, people with the following medical conditions should consult their healthcare provider before taking Prozac or Lexapro:

If pregnant or breastfeeding, consult your healthcare provider for medical advice before taking Prozac or Lexapro.

If you already take Prozac or Lexapro and find out you are pregnant, consult your healthcare provider.

All antidepressants, including Prozac and Lexapro, carry a black box warning.

A black box warning is the strongest warning required by the FDA.

The antidepressant black box warning states that antidepressant use increases the risk of suicidal thoughts and behaviors in children, adolescents, and young adults.

Although this is more common in younger people, people of any age who take an antidepressant should be closely monitored for changes in mood and behavior/worsening of symptoms.

Prozac should not be used in children under seven years old.

Lexapro should not be used in children under 12 years old.

Common side effects of Prozac include but are not limited to:

Common side effects of Lexapro include but are not limited to:

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you have a medical emergency.

In addition to their respective black box warnings, serious side effects of Prozac and Lexapro are similar and may include, but are not limited to:

Prozac is available in oral tablets, oral capsules, and oral solutions. The healthcare provider will start at a lower dose and slowly increase the amount if needed.

When stopping Prozac, the dosage should be gradually tapered to avoid withdrawal symptoms. Prozac can be taken with or without food.

The dosage for each indication in adults is as follows:

Prozac dosage for children and adolescents:

Lexapro is available in the form of an oral tablet and oral solution.

The healthcare provider will start at a lower dose and slowly increase the amount if needed. When stopping Lexapro, the dosage should be gradually tapered to avoid withdrawal symptoms.

Lexapro can be taken with or without food.

The dosage for each indication in adults is as follows:

The dosage for each indication in adults is as follows:

Before taking Prozac or Lexapro, tell your healthcare provider about all your medications, including prescription and OTC medicines, vitamins, or supplements.

While taking Prozac or Lexapro, do not start any new medications without approval from your healthcare provider or pharmacist, including OTC medicines.

Some drug interactions include but are not limited to

Also, it would be best if you avoid alcohol while taking Prozac or Lexapro.

Other drug interactions may occur with Prozac or Lexapro. Consult your healthcare provider for more information about drug interactions and how they may affect you.

Prozac and Lexapro are prescription medications in the SSRI antidepressants class of drugs. Both medications treat depression as well as other mental health conditions.

While these medications have many similarities, they have some differences, too, which are outlined above.

Consult your healthcare provider if you want to know more about these medications and if one may be appropriate for you.

DailyMed. Prozac - fluoxetine hydrochloride capsule.

DailyMed. Lexapro - escitalopram tablet, film coated. Lexapro - escitalopram solution.

Prescribers’ Digital Reference. Fluoxetine hydrochloride - drug summary.

Prescribers’ Digital Reference. Escitalopram oxalate - drug summary.

MedlinePlus. Antidepressants.

Jones LA, Sun EW, Martin AM, Keating DJ. The ever-changing roles of serotonin. Int J Biochem Cell Biol. 2020;125:105776. doi:10.1016/j.biocel.2020.105776

DailyMed. Label: Symbyax- olanzapine and fluoxetine hydrochloride capsule.

Machado-Vieira R, Baumann J, Wheeler-Castillo C, et al. The timing of antidepressant effects: a comparison of diverse pharmacological and somatic treatments. Pharmaceuticals (Basel). 2010;3(1):19-41. doi:10.3390/ph3010019

Kendrick T, Taylor D, Johnson CF. Which first-line antidepressant? Br J Gen Pract. 2019;69(680):114-115. doi:10.3399/bjgp19X701405

Buelt A, McQuaid JR. Comparing clinical guidelines for the management of major depressive disorder. Am Fam Physician. 2023;107(2):123-124.

Adjei K, Adunlin G, Ali AA. Impact of sertraline, fluoxetine, and escitalopram on psychological distress among United States adult outpatients with a major depressive disorder. Healthcare (Basel). 2023;11(5):740. doi:10.3390/healthcare11050740

Epocrates. Escitalopram.

Epocrates. Fluoxetine.

By Karen Berger, PharmDKaren Berger, PharmD, is a community pharmacist and medical writer/reviewer.