Undesirable effects may decrease in intensity and frequency with continued treatment and do not generally lead to cessation of therapy.
In common with other SSRIs, the following undesirable effects have been seen: Body as a whole: Hypersensitivity (eg, pruritus, rash, urticaria, anaphylactoid reaction, vasculitis, serum sickness-like reaction, angioedema), chills, serotonin syndrome, photosensitivity, and, very rarely, toxic epidermal necrolysis (Lyell syndrome).
Digestive system: Gastro-intestinal disorders (eg, diarrhoea, nausea, vomiting, dyspepsia, dysphagia, taste perversion), dry mouth. Abnormal liver function tests have been reported rarely. Very rare cases of idiosyncratic hepatitis.
Nervous system: Headache, sleep abnormalities (eg, abnormal dreams, insomnia), dizziness, anorexia, fatigue (eg, somnolence, drowsiness), euphoria, transient abnormal movement (eg, twitching, ataxia, tremor, myoclonus), seizures, and psychomotor restlessness. Hallucinations, manic reaction, confusion, agitation, anxiety and associated symptoms (eg, nervousness), impaired concentration and thought process (eg, depersonalisation), panic attacks (these symptoms may be due to the underlying disease), and, very rarely serotonin syndrome.
Urogenital system: Urinary retention, urinary frequency.
Reproductive disorders: Sexual dysfunction (delayed or absent ejaculation, anorgasmia), priapism, galactorrhoea.
Miscellaneous: Alopecia, yawn, abnormal vision (eg, blurred vision, mydriasis), sweating, vasodilatation, arthralgia, myalgia, postural hypotension, ecchymosis. Other haemorrhagic manifestations (eg, gynaecological haemorrhages, gastro-intestinal bleedings, and other cutaneous or mucous bleedings) have been reported rarely.
Hyponatraemia: Hyponatraemia (including serum sodium below 110mmol/l) has been rarely reported and appeared to be reversible when fluoxetine was discontinued. Some cases were possibly due to the syndrome of inappropriate antidiuretic hormone secretion. The majority of reports were associated with older patients, and patients taking diuretics or otherwise volume depleted.
Respiratory system: Pharyngitis, dyspnoea. Pulmonary events (including inflammatory processes of varying histopathology and/or fibrosis) have been reported rarely. Dyspnoea may be the only preceding symptom. When stopping treatment, withdrawal symptoms have been reported in association with SSRIs, although the available evidence does not suggest this is due to dependence. Common symptoms include dizziness, paraesthesia, headache, anxiety, and nausea, the majority of which are mild and self-limiting. Fluoxetine has been only rarely associated with such symptoms. Plasma fluoxetine and norfluoxetine concentrations decrease gradually at the conclusion of therapy, which makes dosage tapering unnecessary in most patients.