Prozac Side Effects

Generic Name: fluoxetine

Note: This page contains side effects data for the generic drug fluoxetine. It is possible that some of the dosage forms included below may not apply to the brand name Prozac.

It is possible that some side effects of Prozac may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to fluoxetine: oral capsule, oral capsule delayed release, oral solution, oral syrup, oral tablet

As well as its needed effects, fluoxetine (the active ingredient contained in Prozac) may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking fluoxetine, check with your doctor immediately:

More common
  • Hives
  • inability to sit still
  • itching
  • restlessness
  • skin rash
Less common
  • Chills or fever
  • joint or muscle pain
Rare
  • Anxiety
  • cold sweats
  • confusion
  • convulsions (seizures)
  • cool pale skin
  • diarrhea
  • difficulty with concentration
  • drowsiness
  • dryness of the mouth
  • excessive hunger
  • fast or irregular heartbeat
  • headache
  • increased sweating
  • increased thirst
  • lack of energy
  • mood or behavior changes
  • overactive reflexes
  • purple or red spots on the skin
  • racing heartbeat
  • shakiness or unsteady walk
  • shivering or shaking
  • talking, feeling, and acting with excitement and activity you cannot control
  • trouble with breathing
  • unusual or incomplete body or facial movements
  • unusual tiredness or weakness
Incidence not known
  • Abdominal or stomach pain
  • agitation
  • back or leg pains
  • bleeding gums
  • blindness
  • blistering, peeling, or loosening of the skin
  • bloating
  • blood in the urine or stools
  • bloody, black, or tarry stools
  • blue-yellow color blindness
  • blurred vision
  • chest pain or discomfort
  • clay-colored stools
  • constipation
  • continuing vomiting
  • cough or dry cough
  • dark urine
  • decreased urine output
  • decreased vision
  • depression
  • difficulty with breathing
  • difficulty with swallowing
  • dizziness or lightheadedness
  • eye pain
  • fainting
  • fast, pounding, or irregular heartbeat or pulse
  • general body swelling
  • high fever
  • hives, itching, puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • hostility
  • indigestion
  • irregular or slow heart rate
  • irritability
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • light-colored stools
  • loss of appetite
  • loss of bladder control
  • muscle twitching
  • nausea
  • nightmares
  • noisy breathing
  • nosebleeds
  • pain in the ankles or knees
  • painful, red lumps under the skin, mostly on the legs
  • pains in the stomach, side, or abdomen, possibly radiating to the back
  • pinpoint red spots on the skin
  • rapid weight gain
  • red or irritated eyes
  • red skin lesions, often with a purple center
  • redness, tenderness, itching, burning, or peeling of the skin
  • severe muscle stiffness
  • severe sleepiness
  • slurred speech
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • stopping of heart
  • sudden shortness of breath or troubled breathing
  • sudden weakness in the arms or legs
  • sudden, severe chest pain
  • swelling of the face, ankles, or hands
  • swollen or painful glands
  • thoughts of killing oneself
  • tightness in the chest
  • tiredness
  • twitching, twisting, or uncontrolled repetitive movements of the tongue, lips, face, arms, or legs
  • unconsciousness
  • unpleasant breath odor
  • unusual bleeding or bruising
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • unusually pale skin
  • use of extreme physical or emotional force
  • vomiting of blood
  • yellow eyes or skin

Some fluoxetine side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common
  • Decreased appetite
Less common or rare
  • Abnormal dreams
  • breast enlargement or pain
  • change in sense of taste
  • changes in vision
  • feeling of warmth or heat
  • flushing or redness of the skin, especially on face and neck
  • frequent urination
  • hair loss
  • increased appetite
  • increased sensitivity of the skin to sunlight
  • menstrual pain
  • stomach cramps, gas, or pain
  • unusual secretion of milk, in females
  • weight loss
  • yawning
Incidence not known
  • Cracks in the skin
  • loss of heat from the body
  • painful or prolonged erections of the penis
  • scaly skin
  • swelling of the breasts or breast soreness in both females and males
  • unusual milk production

For Healthcare Professionals

Applies to fluoxetine: compounding powder, oral capsule, oral delayed release capsule, oral solution, oral tablet

Gastrointestinal

A study of 26,005 antidepressant users has reported 3.6 times more upper GI bleeding episodes with the use of SSRIs relative to the population who did not receive antidepressant medications. Upper gastrointestinal tract bleeding was observed in 3.9 times more frequently in patients receiving fluoxetine (the active ingredient contained in Prozac) (Although these studies focused on upper gastrointestinal bleeding, there is reason to believe that bleeding at other sites may also be potentiated.)

Gastrointestinal side effects have frequently included nausea (15% to 21%) and diarrhea (12%). Dry mouth, constipation, dyspepsia, stomatitis, and upper gastrointestinal bleeding have also been reported.

Nervous system

Nervous system side effects including headache, anxiety, nervousness, insomnia, drowsiness, sedation, tremor, dizziness, jitteriness, and fatigue have all been reported. The reported incidence of each of these effects ranges between 4% and 20% of treated patients. Cases of akathisia, neuromuscular twitching, tics, myoclonus, migraines, sleep abnormalities, dyskinesia, acute dystonic reactions, worsening of Parkinson's disease, seizures, stuttering, paresthesias, and cognitive dysfunction have also been reported. Balance disorder and bruxism have also been reported. Postmarketing experience has included memory impairment.

Cases of the neuroleptic malignant syndrome occurring in patients started on fluoxetine have been reported.

One retrospective study of 23 outpatients with Parkinson's disease treated with 40 mg of fluoxetine a day reported that three patients experienced worsening of parkinsonism, two patients experienced improvement of parkinsonism, and 18 patients experienced no change. Another small study reported a series of four patients who experienced worsening of parkinsonism during treatment with fluoxetine.

A number of case reports have implicated fluoxetine in causing seizures. The manufacturer reports that, during premarketing testing, 12 out of 6000 patients experienced convulsions.

A case of dose-dependent exacerbation of preexisting, mild restless legs syndrome (which ultimately required discontinuation of fluoxetine) has been reported.

Nearly all selective serotonin reuptake inhibitors, mixed serotonin/norepinephrine reuptake inhibitors, and tricyclic antidepressants cause sleep abnormalities to some extent. These antidepressants have marked dose-dependent effects on rapid eye movement (REM) sleep, causing reductions in the overall amount of REM sleep over the night and delays the first entry into REM sleep (increased REM sleep onset latency (ROL)), both in healthy subjects and depressed patients. The antidepressants that increase serotonin function appear to have the greatest effect on REM sleep. The reduction in REM sleep is greatest early in treatment, but gradually returns towards baseline during long-term therapy; however, ROL remains long. Following discontinuation of therapy the amount of REM sleep tends to rebound. Some of these drugs (i.e., bupropion, mirtazapine, nefazodone, trazodone, trimipramine) appear to have a modest or minimal effect on REM sleep.

Psychiatric

The reported association between fluoxetine (the active ingredient contained in Prozac) therapy and the development of suicidal ideation is controversial. The 1991 meta-analysis of controlled trials (which was sponsored by the manufacturer of fluoxetine) reported six suicidal acts occurring in a total of 1763 patients treated with fluoxetine. The frequency of suicidal acts was 0.3% and was similar to the frequency reported for placebo (0.2%) and tricyclic antidepressant therapy (0.4%).

Several cases of fluoxetine abuse have been reported in patients with a history of stimulant abuse.

Additionally, several cases of panic attacks and severe nightmares have been associated with fluoxetine therapy.

Postmarketing evidence suggests that SSRIs can cause untoward sexual experiences (e.g., decreases in sexual desire, performance, and satisfaction) and memory impairment.

Psychiatric side effects including hypomania, mania, transient psychosis, development of obsessive-compulsive symptoms, paranoid reaction, delusions, agitation, and a depersonalization syndrome have been reported. A number of reports have suggested that fluoxetine may be associated with the development of suicidal ideation. However, a meta-analysis of controlled studies has suggested that such an association may not exist. A retrospective study of suicidal ideation in 294 patients treated with fluoxetine for depression compared to other patients treated with a variety of therapeutic agents for depression has also suggested that an association between fluoxetine and increased risk of suicidal ideation may not exist.

Other

Nearly all selective serotonin reuptake inhibitors, mixed serotonin/norepinephrine reuptake inhibitors, and tricyclic antidepressants cause sleep abnormalities to some extent. These antidepressants have marked dose-dependent effects on rapid eye movement (REM) sleep, causing reductions in the overall amount of REM sleep over the night and delays the first entry into REM sleep (increased REM sleep onset latency (ROL)), both in healthy subjects and depressed patients. The antidepressants that increase serotonin function appear to have the greatest effect on REM sleep. The reduction in REM sleep is greatest early in treatment, but gradually returns towards baseline during long-term therapy; however, ROL remains long. Following discontinuation of therapy the amount of REM sleep tends to rebound. Some of these drugs (i.e., bupropion, mirtazapine, nefazodone, trazodone, trimipramine) appear to have a modest or minimal effect on REM sleep.

Side effects on sleep have been reported and, in addition to insomnia, include vivid dreaming and an increase in the number of eye movements during non REM sleep.

General

Very rarely, the anorexic effects of fluoxetine (the active ingredient contained in Prozac) have resulted in dramatic and dangerous reductions in body weight. One study of 20 non depressed obese women receiving 60 mg of fluoxetine a day indicated that the drug increased resting energy expenditure and basal body temperature. The author also notes the theory that a higher basal temperature preceding a meal could limit food consumption.

One study has reported that while the initial four weeks of fluoxetine therapy was associated with modest weight loss, weight gain for patients taking fluoxetine for longer periods was not different from the weight gain of control subjects (and was believed to be related to recovery from depression).

General side effects including anorexia (9%) have been reported.

Genitourinary

Genitourinary side effects including sexual dysfunction have been reported. The manufacturer has reported sexual dysfunction side effects at rate of 2%. However, some studies have reported sexual dysfunction in 7.8% to 34% of patients. Specific problems reported include male and female anorgasmia, decreased libido, penile anesthesia, vaginal anesthesia, ejaculatory dysfunction, and impotence. Gynecological bleeding, dysuria and micturition disorder have also been reported. It has been reported that symptoms of sexual dysfunction occasionally persist after discontinuation of fluoxetine (the active ingredient contained in Prozac) treatment.

Clitoral enlargement and prolonged penile erection have been reported.

Cases of improved male sexual function in patients with erectile dysfunction have been reported. Sexual obsessions have also been reported.

Cardiovascular

One placebo-controlled study has suggested that fluoxetine (the active ingredient contained in Prozac) has no effects on intraventricular conduction. Other case reports have suggested that fluoxetine may rarely provoke dysrhythmias. Other conflicting case reports have suggested that fluoxetine may have a propensity to provoke and alleviate vasoconstriction. Several cases of unexpected death occurring shortly after initiation of fluoxetine therapy have been reported in elderly patients with multiple medical problems.

In one case report, QTc prolongation and torsades de pointes developed in an elderly woman 6 months after starting therapy with fluoxetine 20 mg daily. The QTc interval returned to normal following discontinuation of fluoxetine. Four additional cases suggesting fluoxetine associated QTc prolongation or torsades de pointes have been reported.

Cardiovascular side effects including bradycardia have been reported to occur in controlled studies of patients treated with fluoxetine. Several cases of bradycardia-induced syncope have also been reported. Several cases of prolongation of QT interval, ventricular arrhythmia including Torsade de Pointes have been reported in association with fluoxetine treatment. Hypotension has also been reported.

Hematologic

Hematologic side effects include case reports which have suggested that fluoxetine (the active ingredient contained in Prozac) may interfere with platelet function. Petechiae, increased bleeding times, epistaxis, and gastrointestinal hemorrhage have been reported rarely in association with fluoxetine therapy.

Endocrine

Endocrine side effects include case reports which have suggested that fluoxetine (the active ingredient contained in Prozac) may rarely result in the development of the syndrome of inappropriate secretion of antidiuretic hormone (particularly in elderly patients).

Cases of increased serum prolactin and resumption of menses and ovulation have been reported in patients taking fluoxetine.

Dermatologic

Dermatologic side effect including severe hair loss, psoriasis, excessive sweating, and cutaneous hypersensitivity reactions have been reported to occur in association with fluoxetine (the active ingredient contained in Prozac) therapy. Erythema multiforme and toxic epidermal necrolysis have been reported rarely. Alopecia has also been reported.

Approximately 3% of treated patients have been reported to develop a skin reaction.

Ocular

Ocular side effects have included a case report which suggested that fluoxetine (the active ingredient contained in Prozac) may provoke reversible narrow-angle glaucoma. In one study of 20 patients, all patients showed a significant increase in intraocular pressure 2 hours after oral administration of fluoxetine.

Respiratory

Respiratory side effects include a case report that suggested fluoxetine (the active ingredient contained in Prozac) may provoke interstitial pulmonary damage. Another case report described a patient, receiving fluoxetine who developed progressive dyspnea, lung infiltrates, and restrictive lung disease. Pathologic findings were consistent with hypersensitivity pneumonitis. Associated pulmonary phospholipidosis was also noted.

Hypersensitivity

Hypersensitivity side effects involving rash, fever, lymphadenopathy, and arthralgias have been reported in association with fluoxetine (the active ingredient contained in Prozac) use.

Hypersensitivity reactions generally require discontinuation of fluoxetine. Eli Lilly has disclosed 96 reports of serum sickness-like reactions occurring out of 15 million patients treated with fluoxetine.

Immunologic

Immunologic side effects including cases of reactivation of herpes simplex virus infection have been reported in patients treated with fluoxetine (the active ingredient contained in Prozac)

Hepatic

Hepatic side effects including five cases of hepatotoxicity have been reported in association with fluoxetine (the active ingredient contained in Prozac) therapy. Asymptomatic increases in liver enzyme values have been reported in 0.5% of patients receiving long term fluoxetine therapy.

Musculoskeletal

In one study using the healthcare data from the providence of Ontario, Canada reviewing 8,239 patients treated for hip fractures, the adjusted odds ratio for hip fracture was 2.4 for exposure to selective serotonin reuptake inhibitors (including fluoxetine (the active ingredient contained in Prozac) fluvoxamine, paroxetine, and sertraline), compared to participants who had no exposure to antidepressants.

Musculoskeletal side effects may include an increased risk for hip fractures.

Other

Other side effects include a withdrawal type reaction. In one retrospective chart review of 352 patients who were supervised during tapering and discontinuation from serotonin reuptake inhibitor therapy, dizziness, lethargy, paresthesia, nausea, vivid dreams, irritability, and lowered mood were the most common symptoms reported. Patients with at least on qualitatively new symptom were defined in the fluoxetine (the active ingredient contained in Prozac) group at a rate of 1.5%.

Metabolic

Numerous cases of hyponatremia have been reported following treatment with a selective serotonin reuptake inhibitor (SSRI). Risk factors for the development of SSRI associated hyponatremia including advanced age, female gender, concomitant use of diuretics, low body weight, and lower baseline serum sodium levels have been identified. Hyponatremia tends to develop within the first few weeks of treatment (range 3 to 120 days) and typically resolves within 2 weeks (range 48 hours to 6 weeks) after therapy has been discontinued with some patients requiring treatment. The proposed mechanism for the development of hyponatremia involves the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) via release of antidiuretic hormone.

Metabolic side effects including hyponatremia have been reported in patients receiving fluoxetine.

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