Commonly reported side effects of sildenafil include: dyspepsia, headache, visual disturbance, and flushing. Other side effects include: epistaxis, insomnia, nasal congestion, and rhinitis. See below for a comprehensive list of adverse effects.

Applies to sildenafil: oral powder for suspension, oral tablet

Other dosage forms:

• intravenous solution

Along with its needed effects, sildenafil may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking sildenafil:

Less common

• Bladder pain
• burning feeling in the chest or stomach
• burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
• cloudy or bloody urine
• dizziness
• increased frequency of urination
• indigestion
• pain on urination
• stomach upset
• tenderness in the stomach area

Rare

• Abnormal vision
• anxiety
• behavior change similar to drunkenness
• bleeding of the eye
• blurred vision
• bone pain
• breast enlargement
• chest pain
• chills
• cold sweats
• confusion
• convulsions (seizures)
• cool and pale skin
• deafness or hearing loss
• decrease in amount of urine or the frequency of urination
• decreased vision
• difficulty in concentrating
• dizziness or lightheadedness, especially when getting up suddenly from a lying or sitting position
• double vision
• drowsiness
• dry eyes
• dry mouth
• dryness, redness, scaling, or peeling of the skin
• excessive hunger
• eye pain
• fainting or faintness
• fast, irregular, or pounding heartbeat
• feeling of something in the eye
• fever or chills
• headache (severe or continuing)
• increase in the size of the pupil
• increased sweating
• increased thirst
• lower back or side pain
• migraine headache
• nausea (severe or continuing)
• nervousness
• nightmares
• numbness of the hands
• painful, swollen joints
• prolonged, painful erection of penis
• redness, burning, or swelling of the eyes
• redness, itching, or tearing of the eyes
• restless sleep
• seeing shades of colors differently than before
• sensitivity to light
• shakiness
• skin lesions with swelling
• skin paleness
• skin rash, hives, or itching
• skin ulcers
• slurred speech
• sore throat
• sudden weakness
• swelling of the face, hands, feet, or lower legs
• trouble breathing
• twitching of the muscles
• unusual feeling of burning or stinging of the skin
• unusual tiredness or weakness
• vision changes
• vision loss, temporary

Incidence not known

• Blindness

Some side effects of sildenafil may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• Aches or pains in the muscles
• bloody nose
• diarrhea
• difficult or labored breathing
• flushing
• headache
• pain or tenderness around the eyes and cheekbones
• redness of the skin
• sneezing
• stomach discomfort following meals
• stuffy or runny nose
• trouble sleeping
• unusually warm skin

Rare

• Abdominal or stomach pain
• abnormal dreams
• anxiety
• clumsiness or unsteadiness
• cough
• diarrhea or stomach cramps (severe or continuing)
• difficulty in swallowing
• ear pain
• increased amount of saliva
• increased skin sensitivity
• lack of coordination
• loss of bladder control
• mental depression
• nausea
• numbness or tingling of the hands, legs, or feet
• rectal bleeding
• redness or irritation of the tongue
• redness, soreness, swelling, or bleeding of the gums
• ringing or buzzing in the ears
• sensation of motion, usually whirling, either of one's self or of one's surroundings
• sexual problems in men (continuing), including failure to experience a sexual orgasm
• sleepiness
• sores in the mouth and on the lips
• tense muscles
• trembling and shaking
• vomiting
• waking to urinate at night
• worsening of asthma

Applies to sildenafil: intravenous solution, oral powder for reconstitution, oral tablet

The most common adverse reactions reported in clinical trials are headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness, and rash.

Very common (10% or more): Flushing (10%)

Uncommon (0.1% to 1%): Heart rate increased, palpitations, tachycardia, hypertension, hypotension

Rare (less than 0.1%): Myocardial infarction, atrial fibrillation, sudden cardiac death, ventricular arrhythmia, unstable angina

Frequency not reported: Ventricular arrhythmia, sudden cardiac death, angina pectoris, AV block, tachycardia, palpitation, hypotension, postural hypotension, myocardial ischemia, cerebral thrombosis, cardiac arrest, heart failure, abnormal electrocardiogram, cardiomyopathy, shock

Postmarketing reports: Serious cardiovascular, cerebrovascular, and vascular events, including myocardial infarction; sudden cardiac death; ventricular arrhythmia; cerebrovascular hemorrhage; transient ischemic attack; hypertension; subarachnoid, intracerebral, and pulmonary hemorrhage have been reported in temporal association with the use of this drug.

Very common (10% or more): Dyspepsia (up to 17%), diarrhea

Common (1% to 10%): Nausea, vomiting, dry mouth, gastritis, gastroesophageal reflux disease, hemorrhoids, abdominal distension

Rare (less than 0.1%): Oral hypoesthesia

Frequency not reported: Glossitis, colitis, dysphagia, gastroenteritis, esophagitis, stomatitis, gingivitis

Very common (10% or more): Pain in extremity

Common (1% to 10%): Back pain, myalgia

Frequency not reported: Arthritis, arthrosis, myalgia, tendon rupture, tenosynovitis, bone pain, myasthenia, synovitis

Very common (10% or more): Headache (up to 28%)

Common (1% to 10%): Dizziness, migraine, tremor, paresthesia, burning sensation

Uncommon (0.1% to 1%): Somnolence, hypoesthesia

Rare (less than 0.1%): Cerebrovascular accident, syncope

Frequency not reported: Transient ischemic attack, seizure, seizure recurrence, ataxia, hypertonia, neuralgia, neuropathy, paresthesia, somnolence, reflexes decreased

Postmarketing reports: Transient global amnesia

Very common (10% or more): Abnormal vision (up to 11%)

Common (1% to 10%): Visual color distortion, retinal hemorrhage, visual impairment, vision blurred, photophobia, chromatopsia, cyanopsia, eye irritation, ocular hyperemia

Uncommon (0.1% to 1%): Conjunctival disorders, eye disorders, eye pain, lacrimation disorders, visual acuity reduced, diplopia, abnormal sensation in eye, photopsia, visual brightness, conjunctivitis

Rare (less than 0.1%): Retinal hemorrhage, arteriosclerotic retinopathy, retinal disorder, glaucoma, visual field defect, myopia, asthenopia, vitreous floaters, iris disorder, mydriasis, halo vision, eye edema, eye swelling, eyelid edema, scleral discoloration

Frequency not reported: Non-arteritic anterior ischemic optic neuropathy (NAION), retinal vascular occlusion, visual field defect, cataract

This drug has lesser affinity for isoenzyme PDE6, an enzyme found in the retina. This lower selectivity is thought to be the basis for abnormalities related to color vision observed with higher doses or plasma levels.

Nonarteritic anterior ischemic optic neuropathy developed in one eye within minutes to hours after ingestion of sildenafil. Four of the five patients had no vascular risk factors for ischemic optic neuropathy.

-Abnormal Vision: Mild to moderate and transient, predominantly color tinge to vision, but also increased sensitivity to light, or blurred vision.

-Visual color distortions: Chloropsia, chromatopsia, cyanopsia, erythropsia and xanthopsia

-Lacrimation disorders: Dry eye, lacrimal disorder and lacrimation increased

Very common (10% or more): Pharyngitis (18%), rhinitis

Common (1% to 10%): Nasal congestion, epistaxis, cough

Uncommon (0.1% to 1%): Sinus congestion

Rare (less than 0.1%): Throat tightness, nasal edema, nasal dryness

Frequency not reported: Asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, sputum increased, cough increased

Common (1% to 10%): Rash, alopecia, erythema, night sweats

Frequency not reported: Steven-Johnson syndrome (SJS), toxic epidermal necrolysis(TEN), urticaria, herpes simplex, pruritus, sweating, skin ulcer, contact dermatitis, exfoliative dermatitis

Common (1% to 10%): Anemia

Frequency not reported: Leukopenia

Postmarketing reports: In patients with pulmonary arterial hypertension (secondary to sickle cell disease) taking Revatio (R), vaso-occlusive crises requiring hospitalization were more commonly reported. The clinical relevance of this finding in male patients treated with sildenafil for erectile dysfunction is unknown.

Common (1% to 10%): Fluid retention

Frequency not reported: Thirst, edema, gout, unstable diabetes, hyperglycemia, hyperuricemia, hypoglycemic reaction, hypernatremia

Common (1% to 10%): Cellulitis, influenza, bronchitis, sinusitis, rhinitis, gastroenteritis, vertigo, pyrexia

Uncommon (0.1% to 1%): Tinnitus, chest pain, fatigue, gynecomastia

Rare (less than 0.1%): Deafness, irritability

Frequency not reported: Sudden hearing loss, edema, face edema, peripheral edema, pain, chills accidental fall, accidental injury

Common (1% to 10%): Insomnia, anxiety

Frequency not reported: Abnormal dreams, depression

Uncommon (0.1% to 1%): Penile hemorrhage, hematospermia

Frequency not reported: Priapism, prolonged erection, increased erection, cystitis, nocturia, urinary frequency, urinary incontinence, abnormal ejaculation, genital edema, anorgasmia

Uncommon (0.1% to 1%): Hematuria

Rare (less than 0.1%): Hypersensitivity reactions, including rash and urticaria

Frequency not reported: Liver function tests abnormal