Prozac (fluoxetine) is the 31st most prescribed medication in the United States. Nearly twenty-two million Americans take Prozac to treat depression and other psychiatric disorders. It can help improve your day-to-day mood, energy, and interest in life, while reducing panic attacks and the urge to perform repetitive compulsive tasks or binge eat.
What Is Prozac?
Prozac is a prescription-only antidepressant that is used to treat clinical depression, bulimia nervosa (an eating disorder), obsessive-compulsive disorder, panic disorder, and premenstrual dysphoric disorder. It belongs to the class of drugs called selective serotonin reuptake inhibitors (SSRIs) and works in the brain to restore the balance of chemical messengers or neurotransmitters that affect your mood.
Prozac Generic Name
Prozac is a brand name for the generic drug called fluoxetine. Fluoxetine is also sold under another brand name called Sarafem.
The U.S. Food and Drug Administration approved fluoxetine in 1987 which revolutionized the way medications are used to treat mood disorders. Fluoxetine has since become a cornerstone in depression treatment. Eli Lilly and Company was the sole manufacturer of fluoxetine, under the band name Prozac, but after 14 years their exclusivity patent expired. Generic fluoxetine is now available through many different manufacturers.
Fluoxetine is a prescribed medication used to treat the following conditions:
Major depressive disorder
Major depressive disorder, also called clinical depression, is a common and serious mood disorder where you have a persistent feeling of sadness and loss of interest, and you may feel as if life isn’t worth living. You lose interest in activities you once enjoyed and you are unable or find it hard to carry out your day-to-day tasks. Apart from these emotional problems, you may also have physical symptoms such as chronic pain or digestive issues.
According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, also known as the DSM-5, to be diagnosed with major depressive disorder, you will have at least five of the following symptoms where at least one of the symptoms is either a depressed mood or a loss of interest/pleasure. You will have had these symptoms persistently nearly every day for at least two weeks:
- A depressed mood
- A marked loss of interest or pleasure in your usual activities
- A significant change in weight and/or appetite
- A slowing-down of thought and a visible slowing-down of movements, and physical and emotional reactions (psychomotor retardation)
- Fatigue or loss of energy
- Feelings of excessive or inappropriate guilt or worthlessness
- Difficulty thinking and concentrating, or indecisiveness
- Suicidal thoughts, recurrent suicidal ideation, or a suicide plan or attempt
More than 7% of American adults have at least one major depressive episode a year, with more women than men experiencing this disorder.
Bulimia nervosa, also known as bulimia, is an eating disorder that is characterized by uncontrollable binge eating (eating a large amount of food in a short period of time) followed by guilt-induced purging (getting rid of the food consumed in an unhealthy way). People with bulimia purge to get rid of calories and prevent weight gain. Various methods include self-induced vomiting; misuse of laxatives, weight-loss supplements, diuretics, or enemas; fasting or strict dieting when not binge eating; and excessive exercise.
Bulimia is a serious, potentially life-threatening disorder that affects 1.5% of women and 0.5% of men in the United States. You are likely to be preoccupied with your weight and body image, judging yourself harshly for self-perceived flaws, and being very hard on yourself. Since a person with bulimia usually manages to maintain a healthier weight or is only slightly overweight, this eating disorder is often less recognized than serious cases of anorexia nervosa.
According to the DSM-5 criteria, to be diagnosed with bulimia, you need to have recurrent episodes of binge eating. An episode of binge eating is characterized by both of the following:
- Eating, in a discrete period of time (e.g. within any two-hour period), an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances.
- A sense of lack of control over eating during the episode (e.g. a feeling that one cannot stop eating or control what or how much one is eating).
In addition to binge eating, a person with bulimia may also have:
- Recurrent, inappropriate compensatory behavior in order to prevent weight gain, such as self-induced vomiting, misuse of laxatives, diuretics, or other medications, fasting, or excessive exercise.
- The binge eating and inappropriate compensatory behaviors both occur, on average, at least once a week for three months.
- Self-evaluation is unduly influenced by body shape and weight.
- The disturbance does not occur exclusively during episodes of anorexia nervosa.
Panic disorder is classified as an anxiety disorder in the DSM-5. To be diagnosed with panic disorder, you need to:
- Experience unexpected panic attacks on a regular basis
- At least one attack is followed by at least one month of feeling fearful of further attacks and accordingly trying to avoid situations that might induce an attack
- The attacks are not due to the direct physiological effects of a drug, medication, or medical condition
- The attacks are not better accounted for by another mental disorder
The DSM-5 defines two categories of panic attacks: expected and unexpected panic attacks. Expected panic attacks are those linked to a specific fear such as being afraid of flying, whereas unexpected panic attacks have no apparent trigger or cue and may seem to occur out of the blue.
According to DSM-5, a panic attack is characterized by four or more of the following symptoms :
- Palpitations, pounding heart, or accelerated heart rate
- Trembling or shaking
- Sensations of shortness of breath or smothering
- A feeling of choking
- Chest pain or discomfort
- Nausea or abdominal distress
- Feeling dizzy, unsteady, lightheaded, or faint
- Feelings of unreality or being detached from oneself
- Fear of losing control or going crazy
- Fear of dying
- Numbness or tingling sensations
- Chills or hot flashes
If you have fewer than four of the above symptoms, it is considered a limited-symptom panic attack.
Obsessive compulsive disorder
Obsessive compulsive disorder (OCD) is when you get caught up in a cycle of obsessions and compulsions.
Obsessions are repetitive, unwanted, and uncontrollable intrusive thoughts, images, or urges that trigger intensely distressing feelings, including the feeling that things need to be done in the ‘right’ way. Common obsessions with OCD include obsessions related to contamination, losing control, fear of harm, perfectionism, religion, and unwanted sexual thoughts.
Compulsions are behaviors you engage in to attempt to get rid of or escape the obsessions and reduce your distress. Common compulsions include excessive washing and cleaning, checking, and repeating, as well as mental compulsions including mental reviewing, counting, praying, and others.
To be diagnosed with OCD, this cycle of obsessions and compulsions becomes so extreme that it takes up much of your time and prevents you from carrying out other activities you value and would like to do. About 1.2% of American adults have OCD each year.
Premenstrual dysphoric disorder
Premenstrual dysphoric disorder (PMDD) is a condition in which a woman has serious depression, irritability, and tension before menstruation. You may have heard of premenstrual syndrome (PMS) but PMDD is much more severe to the extent that it can prevent a woman from carrying out her normal daily activities and relationships. In both conditions, about 5-11 days before beginning menstruation, a woman will have a wide range of physical or emotional symptoms that will then usually stop once her period starts (or very soon after).
According to the DSM-5 criteria, to be diagnosed with PMDD, you will need to have at least five of the following 11 symptoms, including at least one of the first four listed:
- Marked lability (e.g., mood swings)
- Marked irritability or anger
- Markedly depressed mood
- Marked anxiety and tension
- Decreased interest in usual activities
- Difficulty in concentration
- Lethargy and marked lack of energy
- Marked change in appetite (e.g. overeating or specific food cravings)
- Hypersomnia or insomnia
- Feeling overwhelmed or out of control
- Physical symptoms (e.g. breast tenderness or swelling, joint or muscle pain, a sensation of bloating and weight gain)
Hormonal changes play a role in PMDD and PMS but the actual cause of the conditions are not known. PMDD is estimated to affect approximately 2% of menstruating women, compared to clinically significant PMS in 3-8% of menstruating women
How Does Fluoxetine Work?
Fluoxetine is a medication that belongs to the drug class of selective serotonin reuptake inhibitors (SSRIs). This drug group also contains paroxetine (Paxil), citalopram (Celexa), and sertraline (Zoloft). Depression and other mood disorders are thought to occur due to an imbalance among chemicals called neurotransmitters that are sent between the nerve cells or neurons of your brain. Fluoxetine works by preventing the reuptake or absorption of one neurotransmitter, serotonin, by neurons after it has been released from other neurons. This increases the level of free serotonin that can stimulate your brain’s neurons. Therefore, by balancing the levels of serotonin in the brain, fluoxetine can help enhance your mood, reduce panic attacks, and alleviate the symptoms of other mood disorders.
Before You Take Fluoxetine
Fluoxetine is not a medication that is ideal for everyone with clinical depression, OCD, or other mood disorders. You should not take it if you are aware of an allergy or hypersensitivity to fluoxetine or if you also take pimozide (Orap). Before you take fluoxetine, your doctor will need to go through your medical history and check that you do not have any other health issues which would affect how well this medicine will work. Let you doctor know if you have any of the following:
- Heart disease, high blood pressure, or a stroke
- A bleeding or blood clotting disorder
- Low levels of sodium in your blood
- Liver or kidney disease
- Seizures or epilepsy, being treated with electroconvulsive therapy (ECT)
- Bipolar disorder (manic depression), drug addiction, or suicidal thoughts
- Narrow-angle glaucoma
Fluoxetine is one of the most studied antidepressants in pregnancy. Nevertheless, there is no established evidence that it is absolutely safe to take during pregnancy and while breast-feeding. Talk to your doctor about the benefits and risks of taking your antidepressant while pregnant.
Fluoxetine can potentially interact with numerous medications, increasing or decreasing its concentration in the blood or how well it works. Such fluoxetine interactions can also cause preventable side-effects. It is therefore important that your doctor knows what other medications you are currently taking before prescribing fluoxetine. You also need to make sure you notify your doctor if you start or stop taking over-the-counter (OTC) medications or off-the-counter supplements while on fluoxetine.
Do not use fluoxetine if you have taken a monoamine oxidase inhibitor (MAOI) in the last 14 days or are about to take an MAOI within the next 14 days because this can result in dangerously increased blood pressure and serotonin syndrome.
Fluoxetine has serious interactions with at least 101 different drugs, as well as moderate and mild interactions with other drugs. Here we list some of the most severe drug interactions:
- Methylene blue
Finally, drinking alcohol with fluoxetine should be avoided since this can cause unpleasant but preventable side effects. Be aware that fluoxetine can impair your thinking and reactions so make sure while you are taking this medicine that you are especially careful while driving or carrying out other activities where you need to be alert.
The safety and efficacy of fluoxetine has not been established to treat children younger than eight years old for depression, younger than seven years old for OCD, or at any age younger than 18 years old for OCD, panic disorder, and PMDD.
Fluoxetine is available as a liquid suspension, as immediate-release tablets, and as extended-release (long-acting) capsules. Normally, you take fluoxetine once a day in the morning or twice a day in the morning and at noon (split dosage). You can also take fluoxetine at other times of the day, as long as you stick to the same time each day, but if you have trouble sleeping, it’s best to take it in the morning. Fluoxetine extended-release capsules are usually taken once a week.
Swallow the medication whole without crushing or chewing. You can take fluoxetine with or without food as it doesn’t upset your stomach.
The following are the recommended dosages for immediate-release tablets and suspension for the different conditions that are treated with fluoxetine. After the initial dose, your doctor can slowly increase your dose, if needed, until you reach the optimal dose for you.
- Major depressive disorder: recommended daily dose = 20-60 mg; initial daily dose = 20 mg; maximum daily dose = 80 mg
- Bulimia: recommended daily dose = 60 mg; initial daily dose = 60 mg; maximum daily dose = 60 mg
- Obsessive compulsive disorder: recommended daily dose = 20-60 mg; initial daily dose = 20 mg; maximum daily dose = 80 mg
- Panic disorder: recommended daily dose = 20-60 mg; initial daily dose = 10 mg; maximum daily dose = 60 mg
- Premenstrual dysphoric disorder*: recommended daily dose = 20-60 mg; initial daily dose = 20 mg; maximum daily dose = 80 mg
*for immediate-release tablets starting 14 days before your anticipated date of your period through to the first day of your period and repeated with each new cycle.
What happens if I miss a dose?
Always take your medication according to your doctor’s instructions and what it says on the information sheet that comes with your tablets. If you miss a dose, take it as soon as possible. However, if it is nearly time for your next dose, skip the missed dose and continue with your regular dosing schedule. Never double your dose to compensate for your missed dose.
How long does it take for fluoxetine to take effect?
You will need to be patient when you first start taking fluoxetine since it is slow acting and it can take up to 6-8 weeks before the full effects are seen. However, you may notice a reduction in depressive and other symptoms within 2-4 weeks. You will need to make regular follow-up appointments with your doctor to make sure you are continuing on the best dosage for you. The drug persists for a long time in the body, so it may take a while for you to see an improvement in your mood or a reduction in side effects with dose changes.
Can you stop fluoxetine cold turkey? Does fluoxetine cause withdrawal symptoms?
Do not stop taking fluoxetine, even if you feel better, without discussing it first with your doctor. If you and your doctor find that it is time to stop taking fluoxetine, it is not a good idea to cease the medication suddenly. This is because you can end up with some unpleasant fluoxetine withdrawal symptoms. These can include irritability, nausea, dizziness, vomiting, nightmares, headaches, and/or tingling prickly skin. Instead, discuss with your doctor how you can slowly reduce your dose to avoid any unwanted withdrawal effects.
Common Side Effects
Common Prozac or fluoxetine side effects include but are not limited to:
- Sleep problems (insomnia), strange dreams
- Headache, dizziness, vision changes
- Tremors or shaking, feeling anxious or nervous
- Pain, weakness, yawning, tired feeling
- Upset stomach, loss of appetite, nausea, vomiting, diarrhea
- Dry mouth, sweating, hot flashes
- Changes in weight or appetite
- Stuffy nose, sinus pain, sore throat, flu symptoms
- Decreased sex drive, impotence, or difficulty having an orgasm
Fluoxetine and weight gain
You may gain some weight when taking fluoxetine. Experts are not sure why this happens but it may be that SSRIs cause changes in your body’s metabolism so that you are not as efficiently using up the calories you take in through your food, or because the drug increases your appetite.
What is the most common side effect of Prozac?
The most common side effects of fluoxetine are feeling sick, headaches, and having trouble sleeping but these are usually mild and disappear after a couple of weeks.
Fluoxetine is not for everyone who has clinical depression, bulimia, OCD, or other conditions that are treated with this medication. If for whatever reason fluoxetine is not alleviating your symptoms, or you cannot take fluoxetine due to a pre-existing medical condition or medication that would interact with fluoxetine, there are other treatments that may help you. Talk with your doctor to see whether you can try other medications, various therapies such as cognitive-behavioral therapy, psychotherapy, acceptance and commitment therapy (ACT), or other ‘talk therapies’. Many people who have depression and other mood disorders find such therapies to be of great benefit.
K Health offers K Therapy, a text-based therapy program that includes unlimited messaging with a licensed therapist, plus free resources designed by mental health experts to use on your own.
Prozac vs. Paxil
Prozac (fluoxetine) and Paxil (paroxetine) are similar in that they are both prescription medications used to treat depression and other psychiatric disorders. They also both belong to the same class of drugs called selective serotonin reuptake inhibitors. This means both medications work in a similar way to increase the amount of serotonin in the brain and exert their antidepressant effects.
Despite the similar way Prozac and Paxil work in the brain, there are some differences between these two medications; mainly in how they’re used and their side effects. While both drugs have FDA approval to treat major depressive disorder, panic disorder, obsessive compulsive disorder, and premenstrual dysphoric disorder, Prozac also treats bulimia nervosa, and Paxil also treats generalized anxiety disorder, social anxiety disorder and post-traumatic stress disorder. What’s more, unlike Paxil, Prozac can also treat depression in children aged eight years and older and obsessive compulsive disorder in children seven years and older.
Paxil and Prozac share similar drug interactions and side effects. However, Prozac is a more stimulating SSRI and for this reason it is recommended you take it in the morning rather than the evening, as it is more likely to cause insomnia. Both medications can cause unpleasant withdrawal symptoms if stopped abruptly so make sure that you consult your doctor on how to slowly taper your dose before discontinuing your medicine.
When to See a Doctor
These conditions do not need to take over your life. Seeking professional help can guide you to a treatment that works best for you. Once suitable treatment is found, you will feel much more in control and find life more enjoyable.
It’s time to see your primary care doctor or a mental health specialist for an evaluation if you are experiencing any of the mental and/or physical symptoms discussed above of the conditions treated by fluoxetine. This is especially true if they are severely affecting your ability to function in your daily tasks and interact with other people. Don’t wait for things to become unbearable; there is no shame in getting help and there are many medications and therapies available that can significantly alleviate symptoms. If left untreated, conditions like bulimia can severely impact your health.
At your first visit to the doctor or mental health specialist, he or she will ask you about your feelings and symptoms, how long you’ve had them, and whether you’re changing or limiting your activities as a result. You may also be asked to answer a short questionnaire which will further help your doctor diagnose your condition and determine the severity of your symptoms.
Your doctor or mental health practitioner is there to discuss your concerns, help you find ways of coping you may have not considered before, recommend a form of psychotherapy, and if needed, see if you can benefit from medication. Normally you will be on fluoxetine for at least half a year but make sure you don’t stop suddenly because you may experience unpleasant withdrawal symptoms. You will need regular monthly appointments with your doctor to check all is going as it should. If you feel that your symptoms are getting worse or you are noticing new symptoms, make an appointment with your doctor as soon as possible.
Your family and close friends should be aware you’re on medication so they can support you and also because some young people can have thoughts of suicide when first taking an antidepressant. If you notice mood changes or suicidal ideation, especially in the beginning of treatment, notify your doctor or seek medical attention right away.
If you’re having a mental health emergency, call 911 or go to the nearest emergency room. You can also get free 24/7 support from a suicide and crisis expert by calling or texting 988. If you’d prefer to chat online, you can chat with a suicide and crisis expert by visiting the Lifeline Chat.
If you are taking fluoxetine, be sure to immediately seek emergency medical assistance if you have signs of a rare allergic reaction to fluoxetine. Look out for:
- Skin rash or hives
- Difficulty breathing
- Swelling of your face, lips, tongue, or throat
In the rare case you have a serious side effect, call your doctor straight away. Serious side effects include:
- Vision or eye problems: blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights
- Severe skin reactions: fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads and causes blistering and peeling
- Signs of low salt levels: headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady
- Severe nervous system reactions: very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out
- Signs of serotonin syndrome: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea
If you think you have overdosed on fluoxetine, seek emergency medical attention (by calling 911), or call the poison help line at 1-800-222-1222. Symptoms of overdose can include:
- Blurred vision
- High fever
- Nausea and vomiting
How K Health Can Help
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K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.