Prozac (Fluoxetine): Effects, Withdrawal & Treatment

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Prozac is a SSRI (selective serotonin reuptake inhibitor) antidepressant.

A branded formulation of fluoxetine, Prozac works on neurotransmitters – chemical messengers in the brain – to help some people with depression (major depressive disorder), panic disorder, anxiety disorder, and OCD (obsessive-compulsive disorder).

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Prozac may improve:

  • Mood
  • Sleep
  • Appetite
  • Energy levels

Although SSRIs are generally safe, abusing medications like Prozac – particularly when combined with alcohol or opioids– may trigger the development of psychological dependence. Today’s guide highlights the side effects and withdrawal process associated with Prozac.

What is Prozac?

Prozac is an SSRI antidepressant and a branded form of fluoxetine. Fluoxetine gained FDA approval in 1987, and Prozac was first sold in the U.S. the following year. This paved the way for other SSRIs like Paxil, Zoloft, and Celexa being approved by the FDA to treat depression and other mental health disorders.

What is Prozac Used For?

Prozac is FDA-approved for treating:

  • Depression (major depressive disorder)
  • Panic disorders
  • OCD (obsessive compulsive disorder)
  • Bulimia nervosa
  • PMDD (premenstrual dysphoric disorder)

Like all SSRIs, Prozac stops the brain from reabsorbing naturally-occurring serotonin. Serotonin is a hormone and neurotransmitter associated with mood regulation. By maintaining serotonin levels and streamlining communication between brain cells, Prozac may improve mental wellbeing.

Research indicates that Prozac may be effective for treating major depressive disorder, panic disorder, or anxiety disorder. Effectiveness is improved when the medication is combined with CBT (cognitive behavioral therapy) or other psychotherapies. 

Fluoxetine is available only by prescription in the following forms:

  • Tablets
  • Capsules
  • Delayed-release capsule tablets
  • Oral solution

All forms of Prozac are intended to be taken orally.

Generic versions of the oral capsule are also available.


Prozac dosage will differ from person to person. Here are some average starting doses for the various conditions for which Prozac is prescribed :

For treating depression

  • Adults: Starting dose of 20mg once each morning. Dose will not typically exceed 80mg daily. The dose may be adjusted as needed.
  • Children aged 8+: Starting dose of 10mg to 20mg once each morning. The dose may be adjusted as needed.

For treating depression associated with bipolar disorder combined with olanzapine

  • Adults: Starting dose of 20mg of Prozac and 5mg of olanzapine once daily. Dose will not typically exceed 50mg of Prozac and 12mg of olanzapine daily. The dose may be adjusted as needed.
  • Children aged 10+: Starting dose of 20mg of Prozac and 2.5mg of olanzapine once each evening. Dose will not typically exceed 50mg of Prozac and 12mg of olanzapine daily. The dose may be adjusted as needed.

For treating treatment resistant depression combined with olanzapine

  • Adults: Starting dose of 20mg of Prozac and 5mg of olanzapine once daily. Dose will not typically exceed 50mg of Prozac and 20mg of olanzapine daily. The dose may be adjusted as needed.

For treating panic disorder

  • Adults: Starting dose of 10mg once each morning. Dose will not typically exceed 60mg of Prozac and 12mg of olanzapine daily. The dose may be adjusted as needed.

For treating OCD

  • Adults: Starting dose of 20mg each morning. Dose will not typically exceed 80mg daily. The dose may be adjusted as needed.
  • Children aged 7+: Starting dose of 10mg each morning. Dose will not typically exceed 60mg daily. The dose may be adjusted as needed.

For treating PMDD

  • Adults: Starting dose of 20mg each morning for 15 to 20 days of the menstrual cycle. Dose will not typically exceed 80mg daily. The dose may be adjusted as needed.

For treating bulimia nervosa

  • Adults: Starting dose of 60mg each morning.
an image of a man with his hand on his head by the window, feeling some common side effects of extended use of Prozac, or fluoxetine

Prozac Side Effects

These are the most common side effects of Prozac:

  • Appetite loss
  • Nervousness
  • Anxiety
  • Weakness
  • Nausea
  • Dry mouth
  • Diarrhea
  • Appetite loss
  • Abnormal dreams
  • Stuffy nose
  • Insomnia
  • Heartburn
  • Yawning
  • Memory lapses
  • Difficulty concentrating
  • Confusion
  • Headaches
  • Excessive sweating
  • Erectile dysfunction
  • Reduced libido
  • Tremors
  • Weight loss

If any of these severe Fluoxetine side effects present, consult your primary healthcare provider:

  • Fever
  • Rash
  • Hives
  • Blisters
  • Itching
  • Joint pain
  • Irregular heartbeat
  • Agitation
  • Problems swallowing
  • Bleeding or bruising
  • Loss of motor coordination
  • Difficulty breathing
  • Swelling
  • Fainting
  • Dizziness
  • Shortness of breath
  • Seizure

Fluoxetine may cause appetite loss or weight loss in children.

Long-Term Effects

If you take Prozac as directed by your prescribing physician, Prozac should be safe.

While antidepressants such as Prozac were initially developed for short-term use, some psychiatrists and physicians have been prescribing antidepressants to patients for many years. According to a report in the New York Times, 7% of U.S. over-18s have taken an antidepressant like Prozac for more than five years.

Some people find it challenging to discontinue Prozac after long-term use of the SSRI, even when a physician supervised a tapered dosage reduction. You may experience adverse withdrawal symptoms when you stop taking fluoxetine after sustained use. Some research suggests that many people feel addicted to antidepressants after sustained use, and many experience withdrawal symptoms upon cessation of treatment. Although Prozac is not generally classified as an addictive substance, the medication nevertheless triggers changes in brain chemistry that lead some people to become dependent on the SSRI antidepressant.

Prozac and Alcohol

Mixing Prozac with alcohol is inadvisable and potentially harmful. You should avoid drinking alcohol while taking this medication.

Alcohol is a depressant of the CNS (central nervous system) that affects brain function. Drinking slows and sometimes blocks messages traveling within the brain. It may also trigger the following complications:

  • Depression
  • Anxiety
  • Fatigue
  • Impaired judgment
  • Clouded thinking
  • Vision problems
  • Loss of motor skills

Combining alcohol with Prozac may rapidly trigger increased sedation and extreme drowsiness. This may lead to:

  • Poor decision-making
  • Impaired driving
  • Slips and falls

Combining Prozac and alcohol may also bring about other side effects that may include:

  • Weakness
  • Fatigue
  • Dizziness
  • Hopelessness
  • Suicidal ideation

Alcohol may also prevent Prozac from working effectively.

Additionally, consuming alcohol may inflame symptoms of depression.

Prozac Withdrawal

Prozac withdrawal symptoms may present when you stop using this medication after long-term use.

The symptoms of withdrawal – clinically described as discontinuation syndrome – may last for one to two weeks, depending on the half-life of the substance. A substance is entirely removed from the body after four to five half-lives. Prozac has one of the longest half-lives of all SSRI antidepressants, and is also associated with less withdrawal symptoms than other antidepressants.

Research indicates that one in five of those who use antidepressants for more than one month will experience discontinuation syndrome upon cessation of treatment.


The most common withdrawal symptoms triggered by discontinuing the use of Prozac include:

  • Headaches
  • Dizziness
  • Nausea and vomiting
  • Irritability
  • Nightmares

Prozac Addiction

Although Prozac is not a controlled substance under the CSA (Controlled Substances Act), and it is not a chemically addictive drug, some people develop a psychological addiction to the medication due to the way it affects mood and behavior.

According to data from NSDUH 2021 (National Survey on Drug Use and Health), 14.3 million U.S. over-18s misused prescription medications like fluoxetine in 2021. 

Any abuse of SSRI antidepressants like Prozac can be dangerous. Signs of Prozac abuse may include:

  • Combining Prozac with alcohol or illicit narcotics.
  • Doctor shopping to get more than one prescription for Prozac.
  • Using someone else’s Prozac prescription.
  • Faking symptoms to get more Prozac prescribed.
  • Taking more Prozac than prescribed or increasing the frequency of doses.

Is Prozac Addictive?

Prozac is not chemically addictive, but you may develop a psychological addiction. Some people feel that they require Prozac to sleep or eat well, or to remain happy.

Taking Prozac long-term may also lead to the presentation of withdrawal symptoms when you discontinue use.

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One of the most commonly reported side effects of Prozac is nausea.
You may lose weight when you first start taking Prozac, but over time you may regain that weight or gain extra weight. In general, Prozac is not usually associated with serious weight gain (over 7%). Of all SSRIs, fluoxetine appears to be associated with the least chance for weight gain.


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