Fluoxetine

(floo-ox-uh-teen)

Trade/other name(s): Prozac, Prozac Weekly, Sarafem, fluoxetine hydrochloride

Why would this drug be used?

Fluoxetine is a type of antidepressant known as a selective serotonin reuptake inhibitor (SSRI). It is used to help treat depression, anxiety, panic attacks, obsessive compulsive disorder, and bulimia (binge eating and vomiting). Doctors may prescribe it for other reasons as well.

How does this drug work?

Fluoxetine works by raising levels of a key chemical in the brain called serotonin. Serotonin is linked to the regulation of mood, sleep, and appetite, among other things.

Before taking this medicine

Tell your doctor…

• If you are allergic to any medicines, dyes, additives, or foods.
• If you have ever thought of or attempted suicide. Treatment with an antidepressant may raise the risk of suicidal thoughts, especially during the first few months of treatment.
• If you have bipolar disorder (manic depressive illness). Fluoxetine could make this condition worse.
• If you drink alcohol or are taking any type of sedative. This drug may increase their effects on the nervous system, which in some cases could be dangerous.
• If you ever had liver disease (including hepatitis or cirrhosis). This drug is cleared from the body mainly by the liver. Reduced liver function may result in more drug than expected staying in the body. This could lead to unwanted side effects. Your doctor will want to monitor you closely and may need to adjust your dose accordingly.
• If you have ever had bleeding problems or are taking medicines that might raise your risk of bleeding, such as aspirin or aspirin-containing medicines, other non-steroidal anti-inflammatory drugs (NSAIDs), warfarin (Coumadin), vitamin E, etc. This drug may raise your risk of abnormal bleeding.
• If you have ever had diabetes, seizures, or bipolar disorder (manic depressive illness). This drug could make these conditions worse.
• If you have glaucoma. This drug can make certain types of glaucoma worse.
• If you have any other medical problems such as congestive heart failure, lung disease, heart disease, kidney problems, high blood pressure, gout, or infections. You may need closer monitoring of these conditions while being treated.
• If you have taken monoamine oxidase inhibitors (such as isocarboxazid, phenelzine, selegiline, and tranylcypromine) within the past 2 weeks. Carbamazepine may raise the blood pressure and body temperature, and cause seizures, coma, and even death.
• If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. This drug might cause problems if the woman is taking it at the time of conception or during pregnancy. It is important to check with your doctor about whether birth control should be used with this medicine. In some women who have taken this drug in the weeks before delivery, babies have required longer hospital stays due to problems that may have been related to the drug. Women who are pregnant should discuss this with their doctors before starting to take fluoxetine.
• If you are breast-feeding. This drug passes into breast milk and may affect the baby. Talk with your doctor about the possible risks of breast-feeding while taking this drug.
• About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Fluoxetine may interact with several other drugs and some dietary supplements. Because fluoxetine can stay in the body for weeks after the last dose, some ill effects may be seen if new drugs are started too soon after fluoxetine is stopped.

Antidepressants known as monoamine oxidase inhibitors (MAOIs) such as phenelzine (Nardil) and tranylcypromine (Parnate) may interact with fluoxetine, which could be dangerous. Fluoxetine should not be started while taking an MAOI or within 2 weeks of stopping any of these drugs. MAOIs should not be started while taking fluoxetine or within 5 weeks of stopping fluoxetine.

Pimozide (Orap) and thioridazine (Mellaril) should never be taken with fluoxetine. If you plan to take one of these drugs, you should wait at least 5 weeks after fluoxetine has been stopped. Interactions with these drugs could affect the heart rhythm.

Fluoxetine can raise the levels of phenytoin (Dilantin) and carbamazepine (Tegretol) levels in the blood. If you are on either of these drugs, their dose may need to be lowered if you take fluoxetine.

Fluoxetine may raise the risk of abnormal bleeding. This risk may be increased further if you are taking aspirin or aspirin-containing medicines, other non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen, warfarin (Coumadin), or vitamin E.

Tryptophan supplements and St. John's wort are not recommended while taking fluoxetine.

Drugs that are used to treat migraine or cluster headaches (triptans) can cause an increased risk of serious side effects (see serotonin syndrome information in "Precautions" section) if taken with fluoxetine:

• sumatriptan (Imitrex)
• rizatripan (Maxalt)
• Naratripan (Amerge)
• eletripan (Relpax)
• frovatripan (Frova)
• almotriptan (Axert)
• zolmitriptan (Zomig)

Other drugs that could interact with fluoxetine include:

• sedatives, anxiety medicines, antihistamines, or alcohol
• other antidepressants (amitriptyline, desipramine, doxepin, imipramine, nortriptyline)
• antipsychotics such as haloperidol (Haldol), clozapine (Clozaril), and others
• drugs to help heart rhythm such as propafenone (Rythmol) or flecainide (Tambocor)
• tramadol (Ultram)
• linezolid (Zyvox)
• lithium (Eskalith, Lithobid)
• digoxin (Lanoxin)
• vinblastine (Velban)

Fluoxetine may cause tamoxifen to be less effective.

There may be other drug interactions not listed above. Check with your doctor, nurse, or pharmacist about all of your medicines, herbs, and supplements.

Interactions with foods

Alcohol may have more potent effects on the nervous system while taking fluoxetine. Its use should be minimized or avoided while taking this drug. No other serious interactions with foods are known at this time. Check with your doctor, nurse, or pharmacist about whether some foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Fluoxetine is taken by mouth as a capsule, tablet or liquid. It can be taken with food to lower the chance it will upset your stomach. It can be taken once a day (in the morning) or twice a day (morning and evening), although one form (Prozac Weekly) can be taken once a week.

The dose depends on a number of factors, including the reason the drug is being taken and the patient’s age and liver function. If needed, the dose may be increased after waiting at least a week. Lower doses may be recommended in children, elderly patients, and in those with liver problems.

Do not change the dose or stop taking this drug without first speaking to your doctor or nurse. If you are going to stop taking this drug, it should be done so gradually over the course of several weeks, as directed by your doctor (see "Precautions" section). This drug may stay in your body for several weeks after the last dose is taken. Talk to your doctor before starting any new medicines.

Store the medicine in a tightly closed container and out of the reach of children or pets.

Precautions

This drug may make you feel drowsy when you first start taking it or if the dose is increased. Do not drive or operate heavy machinery until you know how the drug affects you. Use caution if taking cold or allergy medicines, sedatives, anxiety medicines, or sleeping pills or if consuming alcohol while taking this medicine. Talk to your doctor or nurse if you feel too drowsy or it does not go away

This medicine may take 2 weeks or longer to take effect. Do not stop taking this drug without first speaking to your doctor or nurse. If you are going to stop taking fluoxetine, it should usually be tapered down over the course of several weeks, as directed by your doctor. Suddenly stopping the drug can cause anxiety, dizziness, irritability, headache, insomnia, and confusion in some people.

This drug should be used with caution if you have ever had liver disease (including hepatitis or cirrhosis). This drug is cleared from the body mainly by the liver. Reduced liver function may result in more drug than expected staying in the body, which could lead to unwanted side effects. Your doctor will want to monitor you closely and may need to adjust your dose accordingly.

As with other antidepressants this drug may raise the risk of suicidal thoughts and actions, mostly in people up to age 24, especially during the first few months of treatment. If you notice any strange or unusual thoughts or behavior, such as irritability, sleep problems, aggressiveness, restlessness, confusion, panic attacks, or thoughts of suicide while on this medicine, call your doctor. Tell family members, loved ones, and caregivers that you are taking this drug, so that they can help you if they notice behavior changes.

Fluoxetine should be used with caution if you have ever had seizures, bipolar disorder (manic depression), or have ever had bleeding problems. This drug could make these conditions worse.

This drug may lessen saliva production, which can lead to dry mouth and an increased risk of dental cavities or gum disease, especially in older people. Your doctor or nurse should be able to offer suggestions on how to deal with this if needed.

In rare cases, this drug can cause reactions in some people. They can be serious or even life-threatening. They may start with a skin rash but may move on to more serious symptoms, including fever, chills, feeling lightheaded or dizzy (due to low blood pressure), nausea, headache, coughing, shortness of breath, or swelling of the face, tongue, or throat. Stop taking this medicine and get help right away if you develop a rash or have any of these symptoms while taking this drug.

People with diabetes may have changes in their blood sugar. Sometimes the drug lowers blood sugar and requires diabetic medicine doses to be adjusted. Some people have also noticed higher blood sugars after fluoxetine is stopped.

Older people may have low levels of sodium in the blood while on this drug. This is usually found only on blood tests, but if severe, may cause sluggishness, unsteadiness, confusion, muscle twitching, seizures, and coma.

This drug can rarely cause a problem called serotonin syndrome, with symptoms such as nausea, vomiting, diarrhea, headache, restlessness, and confusion. It can also cause bleeding, easy bruising, and trouble walking. This syndrome can become life-threatening if not treated quickly and is more likely if you are taking certain other medicines (see "Interactions with other drugs" section). If you have symptoms like these, call your doctor right away.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.

Common

• nausea
• trouble sleeping
• headache

Less common

• feeling drowsy*
• dry mouth*
• feeling tired or weak
• sweating
• diarrhea
• constipation
• upset stomach
• feeling restless or nervous
• feeling dizzy
• trembling
• loss of appetite
• less interest in sex
• impotence (men)
• decreased ability to reach orgasm

Rare

• skin rash, hives, or itching*
• allergic reaction*
• flu-like symptoms (fever, muscle or joint pain)
• blurred vision
• feeling anxious
• behavior changes such as irritability or panic*
• low blood sodium levels*
• easy bleeding or bruising*
• changes in sexual function that last even after drug is stopped
• suicidal thoughts*

*See "Precautions" section for more detailed information.

There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 1987.

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.