Sildenafil

Sildenafil (Viagra) is taken by mouth to treat erectile dysfunction (ED). You take it only as needed, typically about an hour before sexual activity (but you can take it anywhere between 30 minutes to 4 hours before sex). Don't take sildenafil (Viagra) more than once a day because doing so can put you at higher risk for serious side effects, such as vision loss or low blood pressure. It's available as a lower-cost generic.

What is Sildenafil (Viagra) used for?

• Erectile dysfunction (ED)

How Sildenafil (Viagra) works

Sildenafil (Viagra) is a phosphodiesterase-5 (PDE-5) inhibitor. PDE-5 is a protein in your body that breaks down the molecules that normally cause an erection. When it blocks PDE-5, sildenafil (Viagra) helps an erection occur by allowing certain muscles in the penis to relax and the penis to fill with blood.

The following side effects have also been reported

Along with its needed effects, a medicine 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:

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 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

Tablet

25mg
50mg
100mg

The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is 100 mg. Don't take sildenafil (Viagra) more than once daily (at any dose).

Sildenafil (Viagra) may interact with certain medications or supplements. Always let your doctor and pharmacist know about any other medications or supplements (including prescribed and over-the-counter medications, vitamins, and dietary or herbal supplements) that you are currently taking. The list below does not include all possible drug interactions with Sildenafil (Viagra). Please note that only the generic name of each medication is listed below.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Amprenavir
• Amyl Nitrite
• Atazanavir
• Boceprevir
• Cobicistat
• Darunavir
• Erythrityl Tetranitrate
• Fosamprenavir
• Indinavir
• Isosorbide Dinitrate
• Isosorbide Mononitrate
• Lopinavir
• Molsidomine
• Nelfinavir
• Nitroglycerin
• Nitroprusside
• Pentaerythritol Tetranitrate
• Propatyl Nitrate
• Riociguat
• Ritonavir
• Saquinavir
• Telaprevir
• Tipranavir

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Cannabis
• Ceritinib
• Clarithromycin
• Conivaptan
• Dihydrocodeine
• Duvelisib
• Fluconazole
• Fosnetupitant
• Idelalisib
• Itraconazole
• Ivosidenib
• Larotrectinib
• Lefamulin
• Lorlatinib
• Lumacaftor
• Nefazodone
• Netupitant
• Simeprevir
• Telithromycin
• Voriconazole

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Alfuzosin
• Bosentan
• Bunazosin
• Ciprofloxacin
• Delavirdine
• Doxazosin
• Erythromycin
• Etravirine
• Ketoconazole
• Moxisylyte
• Nebivolol
• Prazosin
• Rifapentine
• Silodosin
• Tamsulosin
• Terazosin
• Trimazosin

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

• Headache (16-28%)
• Flushing (10-19%)
• Indigestion (3-17%)
• Changes in vision or light sensitivity (1-11%)
• Stuffy nose (4-9%)

Other Side Effects

• Back pain
• Dizziness
• Muscle ache
• Nausea
• Rash

Serious Side Effects

Contact your healthcare provider immediately if you experience any of the following.

• Erection lasting for more than 4 hours
• Vision loss
• Dangerously low blood pressure: feeling faint or weak, dizziness, blurry vision, feeling confused

The following side effects have also been reported

Along with its needed effects, a medicine 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:

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 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