Sildenafil is generally well-tolerated and its common adverse effects are mild to moderate and generally transient.
Cardiovascular and Cerebrovascular: Angina pectoris, AV block, cardiac arrest, heart failure, myocardial ischemia, atrial fibrillation, unstable angina, tachycardia, palpitation, increased heart rate, hypotension, postural hypotension, syncope, abnormal electrocardiogram, cardiomyopathy, cerebral thrombosis, cerebrovascular accident, and migraine.
Myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, hypertension, subarachnoid and intracerebral hemorrhages, and pulmonary hemorrhage have also been reported with sildenafil use, mostly in patients with preexisting cardiovascular risk factors.
Gastrointestinal: Vomiting, nausea, glossitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, dry mouth, abnormal liver function tests, rectal hemorrhage, gingivitis, colitis, dyspepsia, diarrhea.
Hematologic and Lymphatic: Anemia and leukopenia, vaso-occlusive crisis requiring hospitalization, flushing.
Metabolic and Nutritional: Thirst, edema, gout, unstable diabetes, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemic reaction, and hypernatremia.
Musculoskeletal: Arthritis, arthrosis, myalgia, tendon rupture, tenosynovitis, bone pain, myasthenia, synovitis, arthralgia.
CNS: Headache, ataxia, hypertonia, neuralgia, neuropathy, paresthesia, tremor, vertigo, depression, anxiety, insomnia, somnolence, abnormal dreams, transient global amnesia, decreased reflexes, hypesthesia, dizziness, seizures, and seizure recurrence.
Respiratory: Asthma, bronchitis, dyspnea, laryngitis, pharyngitis, sinusitis, increase in sputum and cough, nasal congestion, respiratory tract infection, epistaxis.
Skin and Appendages: Urticaria, herpes simplex, pruritus, sweating, skin ulcer, contact dermatitis, and exfoliative dermatitis, rash, Stevens Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN).
Special Senses: Sudden decrease or loss of hearing (see Precautions), tinnitus, ear pain, deafness, mydriasis, conjunctivitis, photophobia, eye pain, eye hemorrhage, cataract, dry eyes, abnormal vision (characterized to be mild and transient such as color tinge to vision, blurred vision and increased sensitivity to light), diplopia, temporary vision loss or decreased vision, ocular redness or bloodshot appearance, lacrimation disorders, ocular burning, ocular swelling or pressure, increased intraocular pressure, retinal vascular disease or bleeding, vitreous detachment or traction, paramacular edema and epistaxis, non-arteritic ischemic optic neuropathy (NAION), resulting in decreased vision and/or permanent vision loss has also been reported (see Precautions).
Urogenital: Cystitis, nocturia, urinary frequency, breast enlargement, urinary incontinence, abnormal ejaculation, genital edema, anorgasmia, urinary tract infection, prolonged erection, priapism, and hematuria.
Immune System Disorders: Hypersensitivity reactions.
Body as a Whole: Face edema, photosensitivity reaction, shock, asthenia, pain, chills, accidental fall, abdominal pain, allergic reaction, chest pain, accidental injury, flu syndrome, fatigue.