• Depression

Increasing Prozac (Fluoxetine) from 20mg to 40mg

Medically reviewed and edited by Dr. Anthony Puopolo

Antidepressants are among the most frequently prescribed medications in the United States. According to the Centers for Disease Control and Prevention (CDC), around 37 million Americans over the age of 12 were taking antidepressants in 2020.

Perhaps the most well-known antidepressant is Prozac (fluoxetine). In the U.S., it is still one of the most popular selective serotonin reuptake inhibitors (SSRIs). It is also one of only a few that the Food and Drug Administration (FDA) has approved for children and teenagers.

In this article, we’ll cover what fluoxetine is, what it is used for, how it works, and what dosages should be used for which condition.

Need to refill a prescription for fluoxetine?

Give your mental health the care it deserves. Schedule an appointment today.

Get Started

What is Fluoxetine?

Fluoxetine (officially known as fluoxetine hydrochloride) is a prescription antidepressant drug that comes in various forms, all of which can be administered orally. These include:

• Capsules

• Delayed-release capsules

• Tablets

• Solutions (also known as an SSRI)

The fluoxetine oral capsule is available as the brand-name drug, Prozac, but there are also generic versions.

The generic drug is usually less expensive than its brand-name counterpart. In some cases, the generic version may not be available in every strength or form, while the brand name drugs offer more variety.

There are many ways that the fluoxetine oral capsule can be used. Sometimes it can even be taken with other medications.

An example of this is when fluoxetine is administered with the drug olanzapine to patients who experience depressive episodes due to bipolar I disorder or treatment-resistant depression.

Fluoxetine is considered safe for human consumption and very serious allergic reactions are rare. However, get medical help right away if you notice any severe side effects.

How Does Fluoxetine Work?

The fluoxetine oral capsule belongs to a class of drugs called selective serotonin reuptake inhibitors (SSRIs) or serotonergic drugs.

They are a type of antidepressant that works by increasing the levels of serotonin within the brain. Serotonin is a neurotransmitter often referred to as the “feel-good hormone.”

Other common SSRIs include:

• Zoloft (Sertraline)

• Viibryd (Vilazodone)

• Celexa (Citalopram)

• Lexapro (Escitalopram)

• Luvox (Fluvoxamine)

• Paxil (Paroxetine)

In the same way that other SSRIs work, fluoxetine increases the amount of serotonin in your brain, which helps you feel better because it keeps your mental state in balance. It specifically helps with symptoms of:

• Depression

• OCD

• Bulimia

• Panic disorder (PD)

What is Fluoxetine Used for?

The fluoxetine oral capsule, also known as Prozac, is used to treat the following:

• Depression: This includes major depressive disorder (MDD) and bipolar disorder (BD).

• Obsessive-compulsive disorder (OCD): This is a mental illness that causes repeated unwanted thoughts or sensations (obsessions) or the urge to do something over and over again (compulsions).

• Bulimia nervosa: This is a potentially life-threatening eating disorder that is characterized by episodes of binge eating followed by inappropriate response behaviors (such as self-induced vomiting; fasting; misuse of laxatives, or excessive exercise).

• Panic attacks: Panic attacks are sudden episodes of intense fear that trigger severe physical reactions when there is no real danger or apparent cause. However, if you've had recurrent, unexpected panic attacks and spent long periods in constant fear of another attack, you may have a condition called Panic Disorder (PD).

A less common condition that is treated with fluoxetine is premenstrual dysphoric disorder (PMDD), a health problem similar to premenstrual syndrome (PMS), only more serious.

Fluoxetine can effectively treat all of the symptoms of PMDD, including:

• Depressed mood

• Anger or irritability

• Trouble concentrating

• Lack of interest in activities once enjoyed

• Moodiness

• Increased appetite

• Insomnia or sleepiness

• Feeling overwhelmed or out of control

Fluoxetine Dosages

There are many different dosages and forms of fluoxetine that can be used. Your dosage, drug form, and drug interactions will all depend on:

• Your age

• The condition being treated

• How severe the condition is

• Other medical conditions you have

• Your reaction to the first dose

The information below shows how dosages differ for four conditions (bulimia, depression, OCD, panic disorder) between different groups:

Generic

• Bulimia: Fluoxetine (oral capsule; 10, 20, 40 mg)

• Depression: Fluoxetine (oral capsule; 10, 20, 40 mg or oral delayed-release capsule; 90 mg)

• OCD: Fluoxetine (oral capsule; 10, 20, 40 mg or oral delayed-release capsule; 90 mg)

• Panic Disorder: Fluoxetine (oral capsule; 10, 20, 40 mg)

Brand name

• Bulimia: Prozac (oral capsule; 10, 20, 40 mg)

• Depression: Prozac (oral capsule; 10, 20, 40 mg)

• OCD: Prozac (oral capsule; 10, 20, 40 mg)

• Panic Disorder: Prozac (oral capsule; 10, 20, 40 mg)

Adult dosage

• Bulimia: 60 mg per day taken in the morning.

• Depression: 20 mg per day taken in the morning, increased to 40 mg (2 x 20 mg) later.

• OCD: A dose range of 20 to 60 mg/day, but can go up to 80 mg/day.

• Panic Disorder: 20 mg per day taken in the morning, increased to 40 mg later.

Senior dosage

• According to the FDA, there is a higher risk of side effects in seniors, so a lower dosage or frequency is recommended.

Does Increasing Fluoxetine from 20mg to 40mg Work?

Research has found that there may be no advantage to increasing doses beyond the calculated beneficial dose for a particular drug.

Many medical practitioners believe that when prescribing fluoxetine, the dosage should be increased to 40 mg if 20 mg does not work, before ruling it out as ineffective.

However, because fluoxetine increases the level of serotonin in the body, increasing its dosage could potentially lead to serotonin syndrome (SS).

Fluoxetine may be prescribed at modest doses and gradually increased over time by your doctor.

However, it may take up to five weeks or more before the full effects of fluoxetine are felt, so be patient.

Tell your doctor if you're unable to sit or stand still because you're feeling restless. Depression or other conditions may be worsened by increasing the dosage of fluoxetine in this scenario.

You should continue to take fluoxetine even if you feel well. Do not stop taking fluoxetine without consulting your doctor.

If you suddenly stop taking fluoxetine, you may experience withdrawal symptoms such as:

• Mood changes

• Irritability

• Dizziness

• Anxiety

• Sweating

• Headaches

• Insomnia

If your healthcare provider decides that it is time for you to stop taking fluoxetine, they will probably decrease your dosage gradually.

How Long Does it Take for Fluoxetine to Work?

Fluoxetine (or Prozac) does not have a rapid or immediate effect on mood, but once it reaches consistent levels in the body, it is a highly effective medication.

Many patients see some improvement from fluoxetine right away, but most people notice the antidepressant effects only after 2-4 weeks of daily use.

Fluoxetine has a longer half-life than many other antidepressants at 2-4 days, which means it remains in your body longer than some other medications.

This long half-life makes it easier to stop fluoxetine than some other antidepressants, which can cause withdrawal symptoms when you stop them abruptly.

What are the Side Effects of Fluoxetine?

Fluoxetine is available as a generic or brand-name drug. Both of these have many side effects, including:

• Nausea

• An upset stomach or constipation

• Headaches

• Anxiety

• Insomnia

• Drowsiness and dizziness

• Nervousness

• Heart palpitations

• Loss of appetite or increase in appetite (fluctuations in weight)

• Cold symptoms (nasal congestion, sneezing, or sore throat)

• Dry mouth

• Decreased sex drive (includes impotence and difficulty having an orgasm)

• Abnormal bleeding (rare, but potentially severe)

If you experience any of these side effects, you should seek medical attention.

Where Can I Learn More About the Treatment of Mental Illnesses?

There are drugs besides fluoxetine that can be used to treat mental health issues. Some other antidepressants may be better suited for you than others. If you're experiencing some of the symptoms that we’ve covered in this article, you can meet with a licensed medical provider from your smartphone, computer, or tablet. Visit LifeMD to make your first appointment.

Dr. Anthony Puopolo

Dr. Puopolo holds a B.A. in Biology from Tufts University, M.A. in Biology from Boston University, and Doctor of Medicine from the Boston University School of Medicine. He also completed a Family Medicine and Psychiatry residency program in the U.S. Army.

Talk To A Doctor

How does LifeMD work?

LifeMD makes it easy to stay on top of your health because talking to a doctor, filling your prescriptions, getting your labs done—and more—are all easy and cost-effective. Come discover a healthcare solution built around you and your life.

Connect with a doctor now!

Join Now

Text

Call