Most of the side effects listed below depend on the dose. With long-term treatment, the severity and frequency of most of these effects is reduced, and there is no need to cancel therapy.
In order of decreasing frequency: frequent (<1/10 and> 1/100); infrequent (<1/100 and> 1/1000); rare (<1/1000); very rare (<1/10000).
General symptoms: weakness, fatigue, headache, abdominal pain, chills, fever.
From the gastrointestinal tract: loss of appetite, constipation, nausea, vomiting, dry mouth; infrequent: grinding of teeth during sleep, reversible increase in activity of liver enzymes; rare: gastrointestinal bleeding; very rare: hepatitis, pancreatitis.
From the nervous system: dizziness, insomnia, agitation, drowsiness; frequent: unusual dreams, anxiety, confused state of consciousness, increased muscle tone, paresthesia, tremor; infrequent: apathy, hallucinations, myoclonus; rare: ataxia, speech disorders, including dysarthria, mania or hypomania (see p.section "Special instructions"), manifestations resembling neuroleptic malignant syndrome, convulsive seizures (see section "Special instructions"), serotonergic syndrome; extrapyramidal disorders, including dyskinesia and dystonia, akathisia (see section "Special instructions"); very rare: delirium.
From the side of the cardiovascular system: Arterial hypertension, widening of blood vessels (blood flow), heart palpitations; infrequent: orthostatic hypotension, syncope, arrhythmias (including tachycardia); Very rare: pirouette arrhythmia, lengthening of the interval QT, ventricular tachycardia, ventricular fibrillation.
From the sense organs: disorders of accommodation, mydriasis, impaired vision, tinnitus; infrequent: a violation of taste.
On the part of the hematopoiesis system: infrequent: hemorrhages in the skin (ecchymosis) and mucous membranes; rare: thrombocytopenia, prolonged bleeding time; very rare: agranulocytosis, aplastic anemia, neutropenia, pancytopenia.
From the skin; sweating, itching and rash; infrequent: reactions of photosensitivity, angioedema, macular-papular rashes,hives; rare: alopecia, erythema multiforme, Stevens-Johnson syndrome.
From the genitourinary system: violations of ejaculation, erection, orgasm, increased frequency of urination; infrequent: decreased libido, impotence, menstrual irregularity, menorrhagia, urinary retention; rare: galactorrhea.
From the side of metabolism: increased serum cholesterol levels (in some cases with prolonged use and, possibly, with high doses), increased or decreased body weight; infrequent: hyponatremia, syndrome of inadequate secretion of antidiuretic hormone; very rare: increased prolactin levels.
Musculoskeletal system: arthralgia, myalgia; infrequent: muscle spasm; very rare: rhabdomyolysis.
After a sharp abolition of venlafaxine or a decrease in its dose, fatigue, drowsiness, headache, nausea, vomiting, anorexia, dry mouth, dizziness, a feeling of faintness, diarrhea, insomnia, nightmares, anxiety, anxiety, disorientation, hypomania, weakness, impaired coordination, ringing in the ears, tremor, convulsions, paresthesia, sweating. These symptoms are usually mild and go untreated.Because of the likelihood of these symptoms, it is very important to gradually reduce the dose of the drug (like any other antidepressant), especially after taking high doses. The length of the period necessary to reduce the dose depends on the size of the dose, the duration of therapy, and the individual sensitivity of the patient.