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Prozac Weekly Side Effects

Generic name: fluoxetine

Medically reviewed by Last updated on Feb 7, 2022.

Note: This document contains side effect information about fluoxetine. Some dosage forms listed on this page may not apply to the brand name Prozac Weekly.

Applies to fluoxetine: oral capsules conventional and delayed-release, oral solution, oral tablets.


  • Antidepressants increased risk of suicidal thinking and behavior (suicidality) compared with placebo in children, adolescents, and young adults (18–24 years of age) with major depressive disorder and other psychiatric disorders; balance this risk with clinical need.1 470 471 Fluoxetine is not approved for use in pediatric patients except for patients with major depressive disorder or obsessive-compulsive disorder.1 (See Pediatric Use under Cautions.)

  • In pooled data analyses, risk of suicidality was not increased in adults >24 years of age and was reduced in adults ≥65 years of age with antidepressant therapy compared with placebo.1 470 471

  • Depression and certain other psychiatric disorders are themselves associated with an increased risk of suicide.1 470 471

  • Appropriately monitor and closely observe all patients who are started on fluoxetine therapy for clinical worsening, suicidality, or unusual changes in behavior; involve family members and/or caregivers in this process.1 470 471 476 (See Worsening of Depression and Suicidality Risk under Cautions.)

Side effects include:

Anxiety, nervousness, insomnia, somnolence, asthenia, tremor, anorexia, nausea, dyspepsia, diarrhea, vasodilation, dry mouth, decreased libido, abnormal ejaculation, impotence, rash, sweating, abnormal dreams, flu syndrome, pharyngitis, sinusitis, yawning.

For Healthcare Professionals

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


The most commonly reported side effects included insomnia, asthenia, and headache.[Ref]

Nervous system

Potentially life-threatening serotonin syndrome has been reported with SSRIs and SNRIs as monotherapy, but particularly with concomitant use of other serotonergic drugs and drugs that impair the metabolism of serotonin.[Ref]

Very common (10% or more): Headache (up to 21%), somnolence (up to 17%), tremor (up to 13%), dizziness (up to 11%)

Common (1% to 10%): Amnesia, hyperkinesia, paresthesia/sensory disturbances, taste perversion/dysgeusia

Uncommon (0.1% to 1%): Abnormal gait, acute brain syndrome, ataxia, balance disorder, central nervous system (CNS) depression, CNS stimulation, dyskinesia, hyperkinesia, hypertonia, hyperesthesia, incoordination, memory impairment, migraine, myoclonus, neuralgia, neuropathy, syncope, vascular headache, vertigo

Rare (0.01% to 0.1%): Abnormal electroencephalogram, cerebral embolism, cerebral ischemia, circumoral paresthesia, convulsion/seizures, delusions, dysarthria, dystonia, extrapyramidal syndrome, foot drop, hyperesthesia, neuritis, paralysis, parosmia, reflexed decreased, serotonin syndrome (neuroleptic malignant syndrome-like effects), stupor, taste loss

Very rare (less than 0.01%): Mild intensity headache

Frequency not reported: Autonomic instability, coma, hyperreflexia, hypersomnia, neuromuscular aberrations, sedation

Postmarketing reports: Cerebrovascular accident, movement disorders, tardive dyskinesia, worsening of preexisting movement disorders[Ref]


Very common (10% or more): Insomnia (up to 33%), anxiety (up to 15%), nervousness (up to 14%)

Common (1% to 10%): Abnormal dreams, agitation, disturbance in attention, emotional lability, hostility, hypomania, mania, personality disorder, restlessness, sleep disorder, tension, thinking abnormal

Uncommon (0.1% to 1%): Akathisia, apathy, bruxism, depersonalization, elevated mood, euphoria, intentional overdose, manic reaction, neurosis, paranoid reaction, psychomotor hyperactivity, psychosis, suicidal thoughts and behavior, suicide attempt

Rare (less than 0.1%): Aggression, antisocial reaction, delusions, dysphemia, hallucinations, panic attacks

Frequency not reported: Activation syndrome, anger, complete suicide, depression, depression suicidal, early morning awakening, initial insomnia, intense dreams, intentional self-injury, mental status changes, middle insomnia, morbid thoughts, nightmares, self-injurious ideation and behavior, sleep disturbances, suicidal ideation

Postmarketing reports: Confusion, discontinuation/withdrawal symptoms, irritability, violent behaviors[Ref]

Antidepressants may have a role in inducing worsening of depression and the emergence of suicidality in certain patients during the early phases of treatment. An increased risk of suicidal thinking and behavior in children, adolescents, and young adults (aged 18 to 24 years) with major depressive disorder (MDD) and other psychiatric disorders has been reported with short-term use of antidepressant drugs.

Adult and pediatric patients receiving antidepressants for MDD, as well as for psychiatric and nonpsychiatric indications, have reported symptoms that may be precursors to emerging suicidality, including anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia, hypomania, and mania. Causality has not been established.[Ref]


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 this drug.[Ref]

Very common (10% or more): Nausea (up to 29%), diarrhea (up to 18%), dry mouth (up to 12%)

Common (1% to 10%): Abdominal pain, constipation, dyspepsia, flatulence, gastrointestinal disorder, vomiting

Uncommon (0.1% to 1%): Aphthous stomatitis, buccoglossal syndrome, colitis, dysphagia, eructation, esophagitis, gastritis, gastroenteritis, gastrointestinal (GI) hemorrhage, glossitis, gum hemorrhage, hyperchlorhydria, increased salivation, melena, mouth ulceration, stomach ulcer, stomatitis

Rare (less than 0.1%): Acute abdominal syndrome, bloody diarrhea, duodenal ulcer, enteritis, esophageal pain, esophageal ulcer, fecal incontinence, hematemesis, intestinal obstruction, pancreatitis, peptic ulcer, salivary gland enlargement, stomach ulcer hemorrhage, tongue edema

Frequency not reported: Anal/esophageal/gastric/upper and lower GI/hemorrhoidal/peritoneal/rectal hemorrhage, bleeding esophageal varices, enterocolitis, esophageal/duodenal/gastric ulcer hemorrhage, GI bleeding, gingival/mouth bleeding, hematochezia, hemorrhagic diarrhea/diverticulitis/gastritis, intraabdominal hemorrhage[Ref]


Very common (10% or more): Rhinitis (up to 23%), pharyngitis (up to 11%), yawn/yawning (up to 11%)

Common (1% to 10%): Epistaxis, sinusitis

Uncommon (0.1% to 1%): Asthma, dyspnea, hiccup, hyperventilation

Rare (less than 0.1%): Apnea, atelectasis, decreased cough, emphysema, hemoptysis, hypoventilation, hypoxia, larynx edema, lung edema, pneumothorax, pulmonary events (inflammatory processes of varying histopathology and/or fibrosis), stridor

Frequency not reported: Increased cough, interstitial lung disease, pneumonitis

Postmarketing reports: Eosinophilic pneumonia, pulmonary embolism, pulmonary hypertension[Ref]


Very common (10% or more): Asthenia/fatigue (up to 21%),

Common (1% to 10%): Accidental injury, chills, ear pain, feeling jittery, fever, lethargy, thirst, tinnitus

Uncommon (0.1% to 1%): Abortion, face edema, feeling abnormal, feeling hot/cold, malaise

Rare (less than 0.1%): Deafness, hypothermia, mucosal hemorrhage

Frequency not reported: Growth delay, hyperthermia, pain

Postmarketing reports: Malignant hyperthermia[Ref]


Decreased weight gain has been observed in association with use in children and adolescents.[Ref]

Very common (10% or more): Anorexia (up to 17%)

Common (1% to 10%): Decreased appetite, increased appetite, weight loss

Uncommon (0.1% to 1%): Dehydration, gout, hypercholesterolemia, hyperlipemia, hypokalemia

Rare (less than 0.1%): Alcohol intolerance, alkaline phosphatase increased, blood sugar level changes, diabetic acidosis, diabetes mellitus, hyperkalemia, hyperuricemia, hypocalcemia, hyponatremia

Frequency not reported: Decreased alkaline phosphatase levels

Postmarketing reports: Hypoglycemia[Ref]


Urinary retention and galactorrhea have been reported with other SSRIs.

The estimates of the incidence of untoward sexual experience and performance may underestimate their actual incidence, partly because patients and physicians may be reluctant to discuss this issue. In placebo-controlled clinical trials ejaculation disorder (primarily ejaculation delay) was reported as a treatment-emergent side effect at an incidence of 6% and at least twice the incidence in placebo-treated male patients.[Ref]

Very Common (10% or more): Decreased libido/loss of libido (up to 11%)

Common (1% to 10%): Abnormal ejaculation/ejaculation disorder, dysmenorrhea, erectile dysfunction, gynecological bleeding, impotence, micturition disorder, urinary frequency

Uncommon (0.1% to 1%): Albuminuria, amenorrhea, anorgasmia, breast enlargement, breast pain, dysuria, female lactation, fibrocystic breast, hematuria, impaired urination, increased libido, leukorrhea, menorrhagia, metrorrhagia, nocturia, pelvic pain, polyuria, sexual dysfunction (occasionally persisting after treatment discontinuation), urinary incontinence, urinary retention, vaginal hemorrhage

Rare (less than 0.1%): Breast engorgement, glycosuria, hypomenorrhea, uterine hemorrhage, uterine fibroids enlarged

Frequency not reported: Delayed ejaculation, delayed sexual maturation, dysfunctional uterine bleeding, ejaculation dysfunction/failure, galactorrhea, genital hemorrhage, menometrorrhagia, orgasmic dysfunction, polymenorrhea, postmenopausal hemorrhage, premature ejaculation, retrograde ejaculation, uterine cervix hemorrhage, vaginal bleeding after drug withdrawal

Postmarketing reports: Enlarged clitoris, pollakiuria[Ref]


Very Common (10% or more): Flu syndrome (up to 12%)

Common (1% to 10%): Infection

Rare (less than 0.1%): Herpes zoster[Ref]


Patients have developed QT prolongation of at least 450 msec.[Ref]

Common (1% to 10%): Chest pain, flushing/hot flush, hypertension, palpitation, QT-interval prolongation, vasodilatation

Uncommon (0.1% to 1%): Angina pectoris, arrhythmia, congestive heart failure, generalized edema, hypotension, myocardial infarct, peripheral edema, postural hypotension

Rare (less than 0.1%): Bradycardia, extrasystoles, heart block, pallor, peripheral vascular disorder, phlebitis, shock, thrombophlebitis, thrombosis, vasculitis, vasospasm, ventricular arrhythmia, ventricular extrasystoles, ventricular fibrillation

Frequency not reported: Labile blood pressure, tachycardia

Postmarketing reports: Atrial fibrillation, heart arrest, torsades de pointes/torsades de pointes-type arrhythmias[Ref]


Common (1% to 10%): Pruritus, rash, sweating/hyperhidrosis, urticaria

Uncommon (0.1% to 1%): Acne, alopecia, cold sweat, contact dermatitis, ecchymosis, eczema, increased tendency to bruise, maculopapular rash, skin discoloration, skin ulcer

Rare (less than 0.1%): Epidermal necrolysis/toxic epidermal necrolysis, erythema multiforme, furunculosis, hirsutism, petechia, photosensitivity reaction, psoriasis, purpura, purpuric rash, seborrhea, Stevens Johnson syndrome/Lyell syndrome

Frequency not reported: Erythema, exfoliative rash, heat rash, erythematous rash, follicular rash, generalized rash, macular rash, morbilliform rash, papular rash, pruritic rash, vesicular rash, umbilical erythema rash

Postmarketing reports: Erythema nodosum, exfoliative dermatitis, thrombocytopenic purpura[Ref]

Alopecia was usually reversible.[Ref]


Common (1% to 10%): Abnormal vision, vision blurred

Uncommon (0.1% to 1%): Conjunctivitis, dry eyes, mydriasis, photophobia

Rare (less than 0.1%): Blepharitis, diplopia, exophthalmos, glaucoma, hyperacusis, iritis, scleritis, strabismus, visual field defect

Frequency not reported: Increased intraocular pressure

Postmarketing reports: Cataract, oculogyric crises, optic neuritis[Ref]


Common (1% to 10%): Arthralgia, muscle twitching/twitching

Uncommon (0.1% to 1%): Arthritis, bone pain, bursitis, leg cramps, tenosynovitis

Rare (less than 0.1%): Arthrosis, chondrodystrophy, creatine phosphokinase increased, myalgia, myasthenia, myopathy, osteomyelitis, osteoporosis, rheumatoid arthritis

Frequency not reported: Back pain, bone fractures[Ref]

Epidemiological studies, primarily in patients aged 50 years or older, have shown an increased risk of bone fractures in patients receiving SSRIs or TCAs.[Ref]


Common (1% to 10%): Allergic reaction

Rare (less than 0.1%): Anaphylactic/anaphylactoid reaction, angioedema, serum sickness[Ref]


Uncommon (0.1% to 1%): Abnormal liver function tests, cholelithiasis

Rare (less than 0.1%): Biliary pain, cholecystitis, hepatitis, idiosyncratic hepatitis, liver fatty deposits, transaminases increased, gamma glutamyltransferase increased

Frequency not reported: Abnormal hepatic function, aggravation of hepatic damage, cholestatic jaundice, hepatic failure/necrosis[Ref]


Rare (less than 0.1%): Blood dyscrasias, hypochromic anemia, iron deficiency anemia, leukopenia, lymphedema, lymphocytosis, neutropenia, thrombocytopenia

Postmarketing reports: Aplastic anemia, eosinophilia, immune-related hemolytic anemia, pancytopenia[Ref]


Uncommon (0.1% to 1%): Hypothyroidism

Rare (less than 0.1%): Inappropriate secretion of antidiuretic hormone

Frequency not reported: Gynecomastia, hyperprolactinemia[Ref]


Uncommon (0.1% to 1%): Albuminuria

Rare (less than 0.1%): Blood urea nitrogen (BUN) increased, kidney pain, oliguria

Postmarketing reports: Kidney failure[Ref]

Frequently asked questions


1. "Product Information. Prozac (fluoxetine)." Dista Products Company (2001):

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Cerner Multum, Inc. "Australian Product Information." O 0

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.