Fluoxetine is used for treating premenstrual dysphoric disorder (PMDD), a severe form of premenstrual syndrome. Fluoxetine is a selective serotonin reuptake inhibitor (SSRI). It works by restoring the balance of serotonin, a natural substance in the brain, which helps to improve mood.
Use Fluoxetine as directed by your doctor.
- Take Fluoxetine by mouth with or without food.
- Taking Fluoxetine at the same time each day will help you remember to take it.
- Continue to take Fluoxetine even if you feel well. Do not miss any doses.
- Do not suddenly stop taking Fluoxetine without checking with your doctor. Side effects may occur. They may include mental or mood changes, numbness or tingling of the skin, dizziness, confusion, headache, trouble sleeping, or unusual tiredness. You will be closely monitored when you start Fluoxetine and whenever a change in dose is made.
- If you miss a dose of Fluoxetine, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.
Ask your health care provider any questions you may have about how to use Fluoxetine.
Store Fluoxetine at room temperature, between 59 and 86 degrees F (15 and 30 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep Fluoxetine out of the reach of children and away from pets.
Do NOT use Fluoxetine if:
- you are allergic to any ingredient in Fluoxetine
- you are taking or have taken a monoamine oxidase inhibitor (MAOI) (eg, phenelzine), selegiline, or St. John’s wort within the last 14 days
- you are taking a fenfluramine derivative (eg, dexfenfluramine), an H1 antagonist (eg, astemizole, terfenadine), nefazodone, pimozide, a serotonin-norepinephrine reuptake inhibitor (SNRI) (eg, venlafaxine), another SSRI (eg, paroxetine), sibutramine, thioridazine, or tryptophan.
Contact your doctor or health care provider right away if any of these apply to you.
Some medical conditions may interact with Fluoxetine. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you or a family member has a history of bipolar disorder (manic-depression), other mental or mood problems, suicidal thoughts or attempts, or alcohol or substance abuse
- if you have a history of seizures, heart problems, liver problems, severe kidney problems, stomach or bowel bleeding, diabetes, or metabolism problems
- if you are dehydrated, have low blood sodium levels, or drink alcohol
- if you will be having electroconvulsive therapy (ECT).
Some medicines may interact with Fluoxetine. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Anorexiants (eg, phentermine), fenfluramine derivatives (eg, dexfenfluramine), linezolid, MAOIs (eg, phenelzine), metoclopramide, nefazodone, selegiline, serotonin 5-HT1 receptor agonists (eg, sumatriptan), sibutramine, SNRIs (eg, venlafaxine), St. John’s wort, trazodone, or tryptophan because severe side effects, such as a reaction that may include fever, rigid muscles, blood pressure changes, mental changes, confusion, irritability, agitation, delirium, or coma, may occur
- Anticoagulants (eg, warfarin), aspirin, or nonsteroidal anti-inflammatory drugs (NSAIDs) (eg, ibuprofen) because the risk of bleeding, including stomach bleeding, may be increased
- Diuretics (eg, furosemide, hydrochlorothiazide) because the risk of low blood sodium levels may be increased
- Tramadol because the risk of seizures may be increased
- Cyclobenzaprine or H1 antagonists (eg, astemizole, terfenadine) because severe heart problems, including irregular heartbeat, may occur
- HIV protease inhibitors (eg, ritonavir) because they may increase the risk of Fluoxetine’s side effects
- Cyproheptadine because it may decrease Fluoxetine’s effectiveness
- Aripiprazole, benzodiazepines (eg, alprazolam), beta-blockers (eg, propranolol), carbamazepine, clozapine, dextromethorphan, digoxin, flecainide, haloperidol, hydantoins (eg, phenytoin), lithium, norepinephrine reuptake inhibitors (eg, atomoxetine), phenothiazines (eg, chlorpromazine, thioridazine), pimozide, propafenone, risperidone, tricyclic antidepressants (eg, amitriptyline), or vinblastine because the risk of their side effects may be increased by Fluoxetine.
This may not be a complete list of all interactions that may occur. Ask your health care provider if Fluoxetine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.
Important safety information:
- Fluoxetine may cause drowsiness or dizziness. These effects may be worse if you take it with alcohol or certain medicines. Take Fluoxetine with caution. Do not drive or perform other possible unsafe tasks until you know how you react to it.
- Check with your doctor before you drink alcohol or use medicines that may cause drowsiness (eg, sleep aids, muscle relaxers) while you are taking Fluoxetine; it may add to their effects. Ask your pharmacist if you have questions about which medicines may cause drowsiness.
- Several weeks may pass before your symptoms improve. Do NOT take more than the recommended dose, change your dose, or take Fluoxetine for longer than prescribed without checking with your doctor.
- Children and teenagers who take Fluoxetine may be at increased risk for suicidal thoughts or actions. Adults may also be affected. The risk may be greater in patients who have had suicidal thoughts or actions in the past. The risk may also be greater in patients who have had bipolar (manic-depressive) illness, or if their family members have had it. Watch patients who take Fluoxetine closely. Contact the doctor at once if new, worsened, or sudden symptoms such as depressed mood; anxious, restless, or irritable behavior; panic attacks; or any unusual change in mood or behavior occur. Contact the doctor right away if any signs of suicidal thoughts or actions occur.
- Diabetes patients – Fluoxetine may affect your blood sugar. Check blood sugar levels closely. Ask your doctor before you change the dose of your diabetes medicine.
- Serotonin syndrome is a possibly fatal syndrome that can be caused by Fluoxetine. Your risk may be greater if you take Fluoxetine with certain other medicines (eg, MAOIs, SSRIs, “triptans”). Symptoms may include agitation; coma; confusion; excessive sweating; fast or irregular heartbeat; fever; hallucinations; nausea, vomiting, or diarrhea; tremor. Contact your doctor at once if you have any of these symptoms.
- Neuroleptic malignant syndrome (NMS) is a possibly fatal syndrome that can be caused by Fluoxetine. Symptoms may include fever; stiff muscles; confusion; abnormal thinking; fast or irregular heartbeat; and sweating. Contact your doctor at once if you have any of these symptoms.
- If your doctor tells you to stop taking Fluoxetine, you will need to wait for several weeks before beginning to take certain other medicines (eg, MAOIs, nefazodone, thioridazine). Ask your doctor when you should start to take your new medicines after you have stopped taking Fluoxetine.
- Fluoxetine may rarely cause a prolonged, painful erection. This could happen even when you are not having sex. If this is not treated right away, it could lead to permanent sexual problems such as impotence. Contact your doctor right away if this happens.
- Fluoxetine contains some of the same ingredients as Prozac, a medicine used to treat depression and other mental problems, and Symbyax, a medicine used to treat depression in patients with bipolar disorder. Do not take Fluoxetine if you are also taking Prozac or Symbyax. Discuss any questions or concerns with your doctor.
- Use Fluoxetine with caution in the elderly; they may be more sensitive to its effects, especially low blood sodium levels.
- Caution is advised when using Fluoxetine in children; they may be more sensitive to its effects, especially increased risk of suicidal thoughts or actions.
- Fluoxetine should be used with extreme caution in children; safety and effectiveness in children have not been confirmed.
- Fluoxetine may cause weight changes. Children and teenagers may need regular weight and growth checks while they take Fluoxetine.
- Pregnancy and breast-feeding: Fluoxetine may cause harm to the fetus if it is used during the last 3 months of pregnancy. If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using Fluoxetine while you are pregnant. Fluoxetine is found in breast milk. Do not breastfeed while you are taking Fluoxetine.
All medicines may cause side effects, but many people have no, or minor, side effects.
Check with your doctor if any of these most common side effects persist or become bothersome:
Anxiety; decreased sexual desire or ability; diarrhea; dizziness; drowsiness; dry mouth; flu-like symptoms (eg, fever, chills, muscle aches); increased sweating; loss of appetite; nausea; nervousness; runny nose; sore throat; stomach upset; trouble sleeping; weakness.
Seek medical attention right away if any of these severe side effects occur:
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue; unusual hoarseness); bizarre behavior; black or bloody stools; chest pain; confusion; decreased concentration; decreased coordination; exaggerated reflexes; excessive sweating; fainting; fast or irregular heartbeat; fever, chills, or sore throat; hallucinations; increased hunger, thirst, or urination; joint or wrist aches or pain; memory loss; new or worsening agitation, panic attacks, aggressiveness, impulsiveness, irritability, hostility, exaggerated feeling of well-being, restlessness, or inability to sit still; persistent or severe ringing in the ears; persistent, painful erection; red, swollen, blistered, or peeling skin; seizures; severe or persistent anxiety, trouble sleeping, or weakness; severe or persistent nausea, vomiting, diarrhea, or headache; significant weight loss; stomach pain; suicidal thoughts or attempts; tremor; unusual bruising or bleeding; unusual hoarseness; unusual or severe mental or mood changes; unusual swelling; unusual weakness; vision changes; worsening of depression.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.