Sildenafil (Viagra, Revatio): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD
What is sildenafil used for?
Sildenafil is commonly used for a variety of sexual and medical conditions, providing significant benefits in improving quality of life for many patients.
- Erectile dysfunction, characterized by the inability to achieve or maintain an erection sufficient for satisfactory sexual performance, which affects millions of men worldwide
- Pulmonary arterial hypertension, a serious condition marked by elevated blood pressure in the pulmonary arteries that can lead to heart failure if untreated
- Other off-label uses, as determined by your healthcare provider, including potential applications in treating altitude sickness and other vascular disorders
In addition to the primary indications, sildenafil may also be prescribed for other conditions at the discretion of your healthcare provider based on individual needs and circumstances.
How does sildenafil work (mechanism of action)?
Sildenafil operates by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which is responsible for the degradation of cGMP, a compound that relaxes smooth muscle and dilates blood vessels. By blocking PDE5, sildenafil enhances blood flow to the penis during sexual arousal, resulting in improved erectile function. In patients with pulmonary arterial hypertension, sildenafil facilitates the relaxation of pulmonary blood vessels, leading to reduced vascular resistance and lower blood pressure in the lungs, thereby alleviating strain on the heart.
How is sildenafil supplied (dosage forms)?
Sildenafil is available in a variety of formulations and dosages tailored to meet different patient needs.
- Brand Names: commonly known as Viagra for erectile dysfunction and Revatio for pulmonary arterial hypertension
- Dosage Forms and Strengths: available as a 10 mg/mL powder for oral suspension, and as oral tablets in strengths of 20 mg, 25 mg, 50 mg, and 100 mg
In addition, sildenafil is available in an injectable form, which is typically administered by healthcare professionals in emergency or clinical settings when necessary.
How should I store sildenafil?
Oral Tablet. Sildenafil oral tablets should be kept in a controlled environment at room temperature, ideally between 68 F to 77 F (20 C to 25 C), with allowances for brief exposures up to 86 F (30 C) during transport. It is essential to store them in a cool, dry place, away from excessive heat and moisture.
Oral Liquid. For sildenafil oral liquid, maintain storage at room temperature below 86 F (30 C) or in a refrigerator, specifically between 36 F to 46 F (2 C to 8 C). Avoid any instances of freezing. Dispose of any remaining liquid after 60 days post-mixing by your pharmacist or healthcare professional.
Injection Liquid. For injectable sildenafil, administration is performed by a healthcare provider, and patients will not be responsible for at-home storage.
Side Effects
What are the most common side effects of sildenafil?
The most frequently reported side effects of sildenafil are as follows. These symptoms can vary significantly depending on the underlying condition being treated. It is important to communicate any adverse effects with your healthcare provider if they become bothersome.
- Headache
- Flushing
- Upset stomach
- Vision changes
- Nasal congestion
- Muscle, back, arm, or leg pain
- Nausea
- Dizziness
- Skin rash
- Diarrhea
- Painful, prolonged erection (priapism)
Other potential side effects of sildenafil may not be listed here. It is crucial to contact your healthcare provider if you suspect you are experiencing a side effect of this medication. In the U.S., side effects may be reported to the FDA through www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, report to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of sildenafil?
While less common, serious side effects associated with sildenafil use include the following, along with specific actions to take should they occur.
Severe Allergic Reactions. Sildenafil can potentially cause allergic reactions, which may be life-threatening. If you experience symptoms of a severe allergic reaction, cease using sildenafil immediately and seek urgent medical assistance.
- Difficulty breathing or wheezing
- Rapid heart rate
- Fever or a general sense of feeling unwell
- Swollen lymph nodes
- Facial, lip, mouth, tongue, or throat swelling
- Difficulty swallowing or throat tightness
- Itching, skin rash, or hives
- Nausea or vomiting
- Lightheadedness, dizziness, or fainting
- Abdominal cramps
- Joint pain
Painful, Prolonged Erection (Priapism). Patients may experience an erection that lasts excessively long and is painful, which can occur independent of sexual stimulation. Immediate medical treatment is crucial to prevent potential lasting damage to the penis. Seek emergency medical care if you notice any of the following:
- Erection that lasts longer than four hours
- Erection not brought on by sexual stimulation
- Pain or tenderness in the penis
Vision Changes. Some users of sildenafil may encounter temporary vision alterations, including a blue tint to vision, color perception changes, blurriness, or light sensitivity. While rare, there are reports of permanent vision loss linked to its use. Immediate medical help should be sought if sudden vision loss occurs in one or both eyes.
Hearing Loss. Reports of sudden hearing loss have emerged among sildenafil users, often accompanied by dizziness or tinnitus (ringing in the ears). Immediate medical attention is warranted if you experience sudden changes in hearing.
Low Blood Pressure (Hypotension). Sildenafil may lead to temporary reductions in blood pressure. Individuals with specific health conditions or those on blood pressure medications are at heightened risk. If you feel faint or dizzy, recline immediately and inform your healthcare provider promptly should you exhibit the following symptoms:
- Lightheadedness or dizziness
- Extreme fatigue or weakness
- Persistent fainting
- Confusion or disorientation
Nosebleeds. Nosebleeds can be a side effect of sildenafil use, with increased occurrence in individuals on blood-thinning medications. Should you experience frequent nosebleeds while on sildenafil, report this to your healthcare provider. If bleeding from the nose is severe or does not stop with pressure, seek emergency assistance immediately.
Warnings & Precautions
Who should not take sildenafil?
Allergy Considerations. Individuals with known allergies to any components of sildenafil should refrain from using this drug.
- Sildenafil
- Revatio
- Viagra
- Other specific ingredients listed in the product information
Your pharmacist can provide detailed information regarding specific ingredients in the sildenafil products available.
Drug Interactions. Use of sildenafil is contraindicated with certain medications. Prior to beginning sildenafil, your healthcare provider must be informed of all medications, OTC products, vitamins, minerals, and herbal supplements you may be taking. Refer to the Interactions section for comprehensive information.
What should I know about sildenafil before taking it?
Only take sildenafil if it has been prescribed specifically for you by a qualified healthcare provider, and adhere strictly to the prescribed dosage and instructions.
Avoid sharing sildenafil with others, even if their condition appears similar to yours. It may pose risks to their health.
Ensure that sildenafil is securely stored out of reach of children. If you have sildenafil oral liquid refrigerated, take additional precautions to keep it away from children who access the refrigerator.
Engaging in sexual activity may place additional stress on your cardiovascular system, which could be problematic for individuals with certain pre-existing health issues, like a recent myocardial infarction. Consult your healthcare provider to ascertain whether it is safe for you to engage in sexual activity. If you experience chest pain, dizziness, or nausea during sexual activity, cease immediately and seek medical assistance.
Sildenafil offers no protection against sexually transmitted infections, including HIV/AIDS.
As a member of the phosphodiesterase-5 (PDE5) inhibitor class of medications, sildenafil is specifically designed for the treatment of erectile dysfunction or pulmonary arterial hypertension. Limit usage to one PDE5 inhibitor at a time, as their combined use can lead to adverse effects. Other drugs in this category include avanafil (Stendra), tadalafil (Cialis), and vardenafil (Levitra).
Utilize an accurate measuring tool when dosing sildenafil oral liquid, as household spoons may lead to inaccurate dosing. Consult your pharmacist for recommendations on suitable measuring devices.
What should I tell my healthcare provider before taking sildenafil?
Inform your healthcare provider of all relevant health conditions and all prescription or OTC medications, supplements, and herbal products you are taking. This will assist them in determining the appropriateness of sildenafil for you.
Be particularly sure to discuss any of the following medical conditions you may have:
Current and Past Health Conditions. It is vital to inform your healthcare provider about any of the following:
- Heart conditions, including arrhythmias, angina, or heart failure
- Recent heart attack, stroke, or cardiovascular procedures within six months
- Documented hypotension
- Persistently high blood pressure despite medication
- Peyronie's disease
- History of prolonged erections lasting beyond four hours
- Blood disorders, such as sickle cell disease
- Inheritable eye diseases like retinitis pigmentosa
- Vision problems or damage to the optic nerve
- Risk factors for optic nerve issues including diabetes, high cholesterol, and older age
- Hearing impairments
- Bleeding disorders
- Gastrointestinal ulcers
- Liver dysfunction
- Severe renal impairment or patients on dialysis
- Pulmonary veno-occlusive disease, which affects pulmonary blood flow
Pregnancy. The effects of sildenafil during pregnancy and potential risks to the fetus remain unclear. It is advisable to discuss this with your healthcare provider if you are pregnant or planning to conceive.
Breastfeeding. Sildenafil can be excreted in breast milk. It is critical to inform your healthcare provider if you are breastfeeding or intend to do so. They can provide guidance on whether sildenafil use during breastfeeding is appropriate.
Interactions
Does sildenafil interact with foods or drinks?
Consuming sildenafil after ingesting a high-fat meal, such as fries with a burger, may delay the onset of its effects, as it can impede the drug's absorption.
Your healthcare provider may suggest avoiding grapefruit or its juice during sildenafil therapy. Grapefruit products can elevate the plasma levels of sildenafil, increasing the likelihood of experiencing side effects or heightened effects of the medication.
Current research suggests that there are no significant interactions between sildenafil and moderate alcohol consumption.
Does sildenafil interact with other medicines (drug interactions)?
Transparency with your healthcare provider regarding all medications, including OTC drugs, dietary supplements, and herbal remedies you are taking is crucial when considering sildenafil. This will ensure safe and effective use.
Particularly disclose any of the following medications before initiating treatment with sildenafil:
- Nitrates, such as nitroglycerin (found in Nitro-Dur, Nitrostat) or isosorbide, often used to relieve chest pain in heart disease; use with sildenafil could lead to dangerously low blood pressure
- Guanylate cyclase stimulators, like riociguat (Adempas) for pulmonary hypertension, could cause severe hypotension when used in conjunction with sildenafil
- Alpha-blockers such as alfuzosin (Uroxatral), doxazosin (Cardura), and others could lead to exacerbated hypotension
- Blood pressure medications like amlodipine (Norvasc) could interact with sildenafil
- Bosentan (Tracleer), used for pulmonary hypertension, may also pose risks when used with sildenafil
- Protease inhibitors such as ritonavir (Norvir), commonly used for HIV treatment, could affect sildenafil metabolism
- Antifungal medications like ketoconazole or itraconazole (Sporanox, Tolsura) might lead to increased sildenafil effects
- Macrolide antibiotics like erythromycin or clarithromycin may alter sildenafil levels
- Other PDE5 inhibitors or erectile dysfunction therapies should not be combined with sildenafil for safety reasons
Additional medications could also affect the pharmacokinetics of sildenafil. Always confirm medication interactions with your healthcare provider.
Does sildenafil interact with other drugs you are taking?
Enter your medication into the WebMD interaction checker
Overdose/Missed Dose
What should I do if I accidentally use too much sildenafil?
In the event of a suspected overdose of sildenafil, seek medical attention without delay. Contact emergency services at 911 or reach out to a Poison Control center at 800-222-1222 for immediate support.
What should I do if I miss a dose of sildenafil?
Erectile Dysfunction. In the context of managing erectile dysfunction, sildenafil is typically used only as needed. Administer it as instructed by your healthcare provider, usually between 30 minutes to four hours before engaging in sexual activity. Double dosing is strictly prohibited.
Pulmonary Arterial Hypertension. For this condition, sildenafil is generally prescribed to be taken three times daily. If you forget a dose, take it as soon as you remember. If the next scheduled dose is near, skip the missed dose and proceed with the next prescribed dose. Consult your healthcare provider if there is uncertainty regarding how to handle a missed dose, and avoid taking double doses.