Sildenafil (Viagra, Revatio): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD
What is sildenafil used for?
Sildenafil is commonly utilized for several medical conditions and concerns. Healthcare professionals may prescribe it for more than one issue, depending on the specific needs of the patient.
- Erectile dysfunction, which is characterized by difficulty in obtaining or sustaining an erection during sexual encounters
- Pulmonary arterial hypertension, a serious condition in which high blood pressure affects the arteries carrying blood from the heart to the lungs
Additionally, sildenafil may be prescribed for other medical conditions as determined by your healthcare provider based on your unique health profile.
How does sildenafil work (mechanism of action)?
Sildenafil operates by inhibiting the enzyme phosphodiesterase type 5 (PDE5) found in the body, which leads to the relaxation of blood vessels in specific areas. In the case of erectile dysfunction, it enhances blood flow to the penis during sexual arousal, facilitating easier attainment and maintenance of an erection. When used for pulmonary arterial hypertension, sildenafil assists in relaxing the pulmonary blood vessels, thereby lowering blood pressure and easing the workload on the heart.
How is sildenafil supplied (dosage forms)?
Brands and other names of sildenafil include
- Viagra
- Revatio
Dosage forms and strengths available include
- 10 mg/mL powder for oral suspension
- 20 mg, 25 mg, 50 mg, and 100 mg oral tablets
In addition, sildenafil is provided in an injectable formulation, typically administered by qualified healthcare providers at medical facilities such as hospitals or clinics.
How should I store sildenafil?
Oral Tablet. Sildenafil oral tablets should ideally be stored at room temperature, specifically between 68 F to 77 F (20 C to 25 C). A brief exposure to temperatures ranging from 59 F to 86 F (15 C to 30 C) is permissible, such as during transport. Always store the medication in a cool, dry environment to maintain its efficacy.
Oral Liquid. If you have sildenafil oral liquid, it should be stored at room temperature below 86 F (30 C) or in the refrigerator between 36 F to 46 F (2 C to 8 C). Ensure that it does not freeze and remember to dispose of any remaining liquid 60 days after it has been mixed by a licensed pharmacist or healthcare professional.
Injection Liquid. Sildenafil in injectable form is generally administered in a clinical setting and will not be stored at home.
Side Effects
What are the most common side effects of sildenafil?
The most frequently reported side effects associated with sildenafil are as follows. These effects may vary based on the specific condition being treated. It is important to inform your healthcare provider if you experience any of these side effects that are bothersome to you.
- Headache
- Flushing
- Upset stomach
- Vision changes (see below)
- Nasal congestion
- Pain in muscles, back, arms, or legs
- Nausea
- Dizziness
- Rash
- Diarrhea
- Painful, prolonged erection (see below)
Other side effects of sildenafil may exist that are not included here. If you suspect you are experiencing any side effects from this medication, contact your healthcare provider promptly. In the United States, side effects can be reported to the FDA via www.fda.gov/medwatch or by calling 800-FDA-1088. For residents in Canada, side effects can be reported to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of sildenafil?
While serious side effects from sildenafil are relatively uncommon, they are significant and should be addressed immediately if they occur. Below are descriptions of these serious effects along with appropriate actions to take in such instances.
Severe Allergic Reactions. An allergic reaction to sildenafil may occur and can be quite serious. Discontinue the use of sildenafil and seek immediate medical help if you experience any of the following symptoms indicative of a severe allergic response.
- Breathing difficulties or wheezing
- Racing heart
- Fever or overall feeling of illness
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Difficulty swallowing or a sensation of tightness in the throat
- Itching, skin rash, or the appearance of red bumps on the skin commonly known as hives
- Nausea or vomiting
- Dizziness, lightheadedness, or fainting
- Severe stomach cramps
- Joint pain
Painful, Prolonged Erection (Priapism). Occasionally, sildenafil may lead to an unwanted erection that is not only prolonged but also painful, occurring without any sexual stimulation. If priapism is not treated swiftly, permanent damage to the penis may transpire. Immediate medical assistance is required if you experience any of the following symptoms of priapism.
- Erection lasting beyond four hours
- Erection happening without any sexual excitement
- Pain or tenderness in the penis
Vision Changes. Some users of sildenafil have reported mild and temporary visual disturbances, which may include seeing a bluish tint, experiencing color abnormalities, having blurred vision, or increased sensitivity to light. While rare, a few individuals have noted permanent vision loss. Should you experience sudden loss of vision in one or both eyes, cease taking sildenafil and seek medical help immediately.
Hearing Loss. There have been instances of sudden hearing loss in users of sildenafil. This may also occur along with symptoms like dizziness and ringing in the ears. In the event of sudden hearing loss or difficulty hearing, promptly stop taking sildenafil and seek medical assistance.
Low Blood Pressure (Hypotension). Sildenafil may induce a mild and temporary reduction in blood pressure levels. Patients with specific health conditions or those taking blood pressure medications may be at a greater risk. If you feel faint, lightheaded, or unusually weak, it is advised to lie down. Please inform your healthcare provider immediately if you notice any of the following symptoms related to low blood pressure.
- Dizziness or lightheadedness
- Excessive tiredness or weakness
- Fainting episodes
- Confusion or disorientation
Nosebleeds. It has been reported that sildenafil may lead to nosebleeds, particularly in those taking anticoagulant medications. Report any frequent episodes of nosebleeds to your healthcare provider. If a nosebleed is severe and does not stop despite applying pressure, seek immediate medical assistance.
Warnings & Precautions
Who should not take sildenafil?
Allergies to Ingredients. Individuals with known allergies to any of the following should avoid taking sildenafil.
- Sildenafil
- Revatio
- Viagra
- Any specific ingredients present in the product dispensed
Your pharmacist is well-equipped to provide detailed information regarding all ingredients found in the specific sildenafil products they supply.
Drug Interactions. It is crucial not to take sildenafil in conjunction with certain other medications. Prior to using sildenafil, inform your healthcare provider about any prescription or non-prescription (OTC) medicines, vitamins/minerals, herbal remedies, and dietary supplements you currently take. Refer to the Interactions section for comprehensive details.
What should I know about sildenafil before taking it?
It is essential to refrain from using sildenafil unless it has been prescribed specifically for you by a qualified healthcare professional. Administer the medication strictly as directed.
Do not share sildenafil with anyone else, even if they have the same ailment as you, as it may be harmful to them.
Ensure that sildenafil is kept out of reach of children. If you store sildenafil oral liquid in a refrigerator, be sure to place it in an area inaccessible to children who may also access the refrigerator.
Engaging in sexual activities can place additional stress on your heart, which may pose dangers for individuals with certain preexisting heart conditions, such as those who have experienced a recent heart attack. Consult your healthcare provider to evaluate whether your heart is in a suitable condition for sexual activity. If you experience chest pain, dizziness, or nausea during sexual intercourse, cease activity immediately and contact your healthcare provider without delay.
It is important to note that sildenafil does not provide protection against sexually transmitted infections, including HIV.
Sildenafil is classified as a phosphodiesterase-5 (PDE-5) inhibitor, utilized for the treatment of erectile dysfunction and pulmonary arterial hypertension. It is important to never take more than one PDE-5 inhibitor medication at a time. Other medications in this category include avanafil (Stendra), sildenafil (under various names), tadalafil (Cialis and similar products), and vardenafil (Levitra, Staxyn).
When measuring your dose of sildenafil oral liquid, be sure to use a precise measuring device. Household spoons are not considered accurate measuring instruments and could lead to incorrect dosing. Consult your pharmacist for recommendations on appropriate measuring devices.
What should I tell my healthcare provider before taking sildenafil?
It is vital to inform your healthcare provider about all pre-existing health conditions as well as any prescription or non-prescription (OTC) medications, vitamins/minerals, herbal supplements, and other dietary aids you are using. This will aid them in determining whether sildenafil is appropriate for you.
In particular, make sure to bring up any of the following conditions.
Current and Past Health Conditions. Ensure that your healthcare provider is aware if you have any of the following health issues.
- Cardiac complications, including issues such as heart rhythm abnormalities, chest pain, or heart failure
- History of heart attack, stroke, or heart surgery within the previous six months
- Low blood pressure readings
- Persistently high blood pressure that remains unmanageable despite treatment
- Peyronie's disease, characterized by a curvature or deformity of the penis
- An erection lasting over four hours
- Any blood disorders, such as sickle cell anemia
- An inherited eye condition known as retinitis pigmentosa
- Vision loss or a condition affecting the optic nerve
- Health issues or risk factors contributing to optic nerve complications, including diabetes, elevated cholesterol, smoking habits, advancing age, or specific eye exam findings like a “crowded disc”
- Any auditory issues or hearing impairments
- Any history of bleeding disorders
- Stomach ulcers
- Liver dysfunction or disease
- Severe kidney issues or if you are undergoing dialysis treatment
- Pulmonary veno-occlusive disease, which involves blockages in lung blood vessels
Pregnancy. The effects of sildenafil on pregnancy, and its potential risks to an unborn child, are not yet well-understood. It is essential to inform your healthcare provider if you are currently pregnant or planning to become pregnant soon.
Breastfeeding. Sildenafil can be found in breast milk. If you are breastfeeding or plan to breastfeed, discuss this with your healthcare provider. They can advise you on the advisability of taking sildenafil during this period.
Interactions
Does sildenafil interact with foods or drinks?
Taking sildenafil after consuming a meal high in fat, such as fast food, may result in a delayed onset of its effects.
Your healthcare provider might also recommend avoiding grapefruit or grapefruit juice during the course of sildenafil treatment, as these can elevate sildenafil concentrations in your bloodstream, increasing the likelihood of experiencing side effects.
Additionally, there are no known adverse interactions between sildenafil and alcohol consumption.
Does sildenafil interact with other medicines (drug interactions)?
Always communicate with your healthcare provider regarding any prescription or non-prescription (OTC) medications, as well as vitamins/minerals, herbal remedies, and dietary supplements you may also be taking.
It is crucial to particularly mention if you are using any of the following before initiating sildenafil treatment.
- Any nitrates, such as nitroglycerin (found in various formulations like Nitro-Dur or Nitrostat) or isosorbide, which are commonly prescribed for chest pain associated with heart disease, or recreational drugs like amyl nitrite (“poppers”)
- Guanylate cyclase stimulators, including riociguat (Adempas), prescribed for pulmonary arterial hypertension, or vericiguat (Verquvo), utilized for certain heart failure conditions
- Alpha-blockers such as alfuzosin (Uroxatral), doxazosin (Cardura), dutasteride, prazosin (Minipress), silodosin (Rapaflo), tamsulosin (Flomax), or terazosin (Hytrin), which may be employed for hypertension or related urinary concerns due to prostate enlargement
- Antihypertensive medications, including amlodipine (Norvasc)
- Bosentan (Tracleer), a medication for pulmonary arterial hypertension
- Protease inhibitors, such as ritonavir (Norvir), often prescribed for HIV treatment
- Antifungal agents like ketoconazole or itraconazole (Sporanox, Tolsura)
- Antibiotics such as erythromycin (Ery-Tab and others) or clarithromycin (Biaxin), utilized for bacterial infections
- Any other medication prescribed for erectile dysfunction or pulmonary arterial hypertension
Other medications might modify the blood levels of sildenafil. It is imperative to inform your healthcare provider about all medications you are currently taking or have taken recently.
This summary may not encompass all medications that could interact with sildenafil. Always consult your healthcare provider for further guidance.
Does interact with other drugs you are taking?
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Overdose/Missed Dose
What should I do if I accidentally use too much sildenafil?
In the event that you or someone else has ingested a quantity of sildenafil that exceeds the prescribed dose, it is vital to seek medical assistance immediately—call emergency services at 911 or contact a Poison Control center at 800-222-1222 without delay.
What should I do if I miss a dose of sildenafil?
Erectile Dysfunction. In this case, sildenafil is to be consumed only when necessary. Follow your healthcare provider’s instructions, typically taking it between 30 minutes and four hours prior to planned sexual activity. Never take more than the prescribed or extra doses.
Pulmonary Arterial Hypertension. When prescribed for this purpose, sildenafil is usually taken three times daily. If you happen to miss a dose, take it as soon as you remember. However, if the next scheduled dose is approaching, skip the missed dose and proceed with your regular dosing schedule. Consult your healthcare provider if you are uncertain regarding the appropriate steps to take following a missed dose. Do not take multiple doses at once.