Usually the side effects of sildenafil are weak or moderate and are transient.
According to WHO, the side effects are classified in relation to their developmental frequency as follows: very often (> 1/10), often (1/10 - 1/100), infrequently (1/100 - 1/1000), rarely (1 / 1000 - 1/10 000), very rarely (<1/10 0000) appointments, including individual cases, and the frequency is unknown (can not be determined from available data).
Allergic reactions: infrequently - reactions of hypersensitivity (including skin rash), allergic reactions.
From the sense organs: often - blurred vision, impaired vision, cyanopsy; infrequently - pain in the eyes, photophobia, photopsy, chromatopsy, reddening of eyes / injections of sclera, change in brightness of light perception, mydriasis, conjunctivitis, eye hemorrhage, cataract, tearing device failure, sudden decrease or loss of hearing, tinnitus, pain in ears; rarely - edema of the eyelids and adjacent tissues, dry eyes, the presence of iridescent circles in the field of view around the light source, increased eye fatigue, vision of objects in yellow color (xanthopsia), vision of objects in red (erythropsy), conjunctival hyperemia, mucosal irritation shells of the eyes, unpleasant sensations in the eyes; frequency unknown - non-arteritis anterior ischemic optic nerve neuropathy (NPINZN), retinal vein occlusion,visual field defects, diplopia, temporary loss of vision or blurred vision, increased intraocular pressure, retinal edema, retinal vascular diseases, vitreous detachment / vitreal traction.
From the cardiovascular system: often - "tides"; infrequently - tachycardia, palpitations, lowering blood pressure, increased heart rate, unstable angina, atrioventricular block, myocardial ischaemia, cerebral thrombosis, cardiac arrest, cardiac failure, abnormalities in electrocardiogram readings, cardiomyopathy; rarely - atrial fibrillation.
On the part of the organs of hematopoiesis: infrequently - anemia, leukopenia.
From the side of metabolism: infrequently - a feeling of thirst, swelling, gout, uncompensated diabetes mellitus, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemia, hypernatremia.
From the respiratory system: often - nasal congestion; infrequently - epistaxis, rhinitis, asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, increased sputum volume, increased cough; rarely - a feeling of tightness in the throat, dryness of the mucous membrane of the nasal cavity, swelling of the nasal mucosa.
From the digestive system: often - nausea, indigestion; infrequently - gastroesophageal reflux disease, vomiting, abdominal pain, dryness of the oral mucosa, glossitis, gingivitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, deviation "liver" functional test of a fault, rectal bleeding; rarely - hypoesthesia of the oral mucosa.
From the side of the musculoskeletal system: often - pain in the back; infrequently - myalgia, pain in the extremities, arthritis, arthrosis, tendon rupture, tenosynovitis, bone pain, myasthenia gravis, synovitis.
From the genitourinary system: infrequently - cystitis, nocturia, breast enlargement (males), incontinence, hematuria, abnormal ejaculation, genital edema, anorgasmia, haemospermia, penile tissue damage; rarely - a prolonged erection and / or priapism.
From the central and peripheral nervous system: very often - headache; often - dizziness; infrequently - drowsiness, migraine, ataxia, hypertonus, neuralgia, neuropathy, paresthesia, tremor, vertigo, symptoms of depression, insomnia, unusual dreams, increased reflexes, hypoesthesia; rarely - convulsions, repeated convulsions, fainting.
From the skin: infrequent - skin rash, hives, herpes simplex, pruritus, increased sweating, skin ulceration, contact dermatitis, exfoliative dermatitis; frequency is unknown - Stevens-Johnson syndrome, toxic epidermal necrolysis.
Other: infrequent - fever, facial swelling, photosensitivity reaction, shock, asthenia, fatigue, pain of different locations, chills, accidental falls, pain in the chest, accidental trauma; rarely - irritability.
Cardiovascular complications
During the postmarketing use of sildenafil, adverse events such as severe cardiovascular complications (including myocardial infarction, unstable angina, sudden cardiac death, ventricular arrhythmia, hemorrhagic stroke, transient ischemic attack, hypertension and hypotension) were reported for the treatment of erectile dysfunction. who had a temporary connection with the use of sildenafil. Most of these patients, but not all of them, had risk factors for cardiovascular complications. Many of these adverse events were observed soon after sexual activity, and some of them were noted after taking sildenafil without subsequent sexual activity.It is not possible to establish the presence of a direct link between the observed undesirable phenomena and these or other factors.
Visual disorders
In rare cases, during the post-marketing application of all PDE5 inhibitors, including sildenafil, non-arteritis anterior ischemic optic neuropathy (NPINZN) was reported - a rare disease and the cause of a decrease or loss of vision. Most of these patients had risk factors, in particular, a reduction in the ratio of the diameter of the excavation and the optic disc ("stagnant disk"), age over 50 years, diabetes, hypertension, coronary heart disease, hyperlipidemia and smoking. In the observational study, it was assessed whether the recent use of preparations of the class of PDE5 inhibitors with the acute onset of NPINZH was related. The results indicate an approximately 2-fold increase in the risk of NPIIV within 5 half-lives after the use of the PDE5 inhibitor. According to the published literature, the annual incidence of NPIH is 2.5-11.8 cases per 100 000 men aged ≥ 50 years in the general population.It should be recommended to patients in the event of a sudden loss of vision to stop sildenafil therapy and immediately consult a doctor. Persons who already had a case of NPINZ have an increased risk of recurrence of NPINZN. Therefore, the physician should discuss this risk with such patients, and discuss with them the potential risk of adverse effects of PDE5 inhibitors. PDE5 inhibitors, including sildenafil, these patients should be used with caution and only in situations where the expected benefit outweighs the risk.
When sildenafil was used in doses exceeding the recommended levels, the adverse events were similar to those noted above, but were usually more common.