The most common side effects were headache and "hot flashes".
Typically, the side effects of Viagra are "weak or moderately expressed and transient.
In studies using a fixed dose, it has been shown that the incidence of certain adverse events increases with increasing doses.
The frequency of unwanted reactions is represented by the following classification:
| Often | ≥10% |
| Often | ≥1% and <10% |
| Infrequently | ≥0,1% and <1% |
| Rarely | ≥0,01% and <0,1% |
| Rarely | <0,01% |
| Frequency unknown | It is impossible to determine from the available data |
From the immune system: infrequently - reactions of hypersensitivity (including skin rash), allergic reactions.
From the side of the organ of vision: 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, cataracts, tearing device malfunction; rarely - swelling of the eyelids and adjacent tissues, dry eyes, the presence of rainbow 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,irritation of the mucous membrane of the eyes, unpleasant sensations in the eyes; frequency is unknown - neartsriitnaya anterior ischemic optic neuropathy, 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 side of the hearing organ: infrequent - sudden decrease or loss of hearing, tinnitus, pain in the ears.
From the side of the cardiovascular system: often - "tides"; infrequently - tachycardia, palpitations, lowering blood pressure, increased heart rate, unstable angina, atrioventricular block, myocardial infarction, cerebral thrombosis, cardiac arrest, cardiac failure, abnormalities in electrocardiogram readings, cardiomyopathy; rarely - atrial fibrillation, sudden cardiac death *, ventricular arrhythmia *.
From the side of the blood and lymphatic system: infrequently - anemia, and leukopenia.
From the side of metabolism and nutrition: 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 mucous membrane of the nasal cavity.
From the gastrointestinal tract: 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, enlargement of the mammary glands, urinary incontinence, hematuria, ejaculation disorder, edema of the genitals, anorgasmia, hematospermia, damage to the tissues of the penis; 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 and subcutaneous tissues: 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 - a sensation of fever, face swelling, photosensitivity reaction, shock, asthenia, fatigue, pain of different localization, chills, accidental falls, pain in the chest, accidental trauma; rarely - irritability.
* Side effects identified during post-marketing research.
Cardiovascular complications
During the postmarketing use of sildenafil for the treatment of erectile dysfunction, adverse events such as severe cardiovascular complications were reported (incl.myocardial infarction, unstable angina, sudden cardiac death, ventricular arrhythmia, hemorrhagic stroke, transient ischemic attack, hypertension and hypotension), which 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 chance 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 using Viagra® in doses exceeding the recommended levels, the undesirable effects were similar to those noted above, but were usually more frequent.