Sildenafil (Viagra, Revatio): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD
What is sildenafil used for?
Sildenafil is commonly utilized for a variety of medical conditions, primarily those associated with certain forms of sexual dysfunction and pulmonary issues, making it a versatile medication within the field of pharmacology.
- Erectile dysfunction, a condition characterized by difficulties in achieving or maintaining an erection sufficient for sexual intercourse, which can impact psychological well-being and relationship satisfaction.
- Pulmonary arterial hypertension, a serious condition where high blood pressure occurs in the arteries of the lungs, leading to symptoms such as shortness of breath and fatigue, significantly affecting quality of life.
In addition to the above, sildenafil may also be prescribed for other conditions as deemed appropriate by your healthcare provider based on individual patient needs and medical history.
How does sildenafil work (mechanism of action)?
The therapeutic action of sildenafil lies in its ability to inhibit the phosphodiesterase type 5 (PDE5) enzyme, which plays a key role in regulating blood flow in various tissues. By blocking PDE5, sildenafil promotes vasodilation, particularly in the penile vasculature, thereby enhancing blood flow during sexual arousal. This mechanism is also beneficial in pulmonary arterial hypertension, as it aids in relaxing blood vessels in the lungs, resulting in decreased pulmonary pressure and reduced workload on the heart.
How is sildenafil supplied (dosage forms)?
Brands and other names
- Viagra
- Revatio
Dosage forms and strengths
- 10 mg/mL powder for oral suspension
- 20 mg, 25 mg, 50 mg, 100 mg oral tablets
Moreover, sildenafil is available in an injectable formulation, which is typically administered in a clinical setting under the supervision of healthcare professionals for immediate therapeutic effect.
How should I store sildenafil?
Oral Tablet. Sildenafil oral tablets should be properly stored at room temperature, ideally between 68°F to 77°F (20°C to 25°C). They can endure brief exposure to temperatures ranging from 59°F to 86°F (15°C to 30°C) during transport but should remain in a cool, dry environment otherwise.
Oral Liquid. Sildenafil oral liquid preparations should be kept at room temperature below 86°F (30°C) or refrigerated within the range of 36°F to 46°F (2°C to 8°C), taking care to avoid freezing temperatures. Any remaining solution should be discarded after 60 days from the mixing date as per pharmacy guidelines.
Injection Liquid. The injectable form of sildenafil is typically administered by healthcare personnel in a controlled hospital or clinical environment, and thus, storage at home is not applicable.
Side Effects
What are the most common side effects of sildenafil?
As with any medication, sildenafil can lead to a variety of side effects; the most frequently reported ones include the following. It is essential to communicate with your healthcare provider about any adverse effects experienced during treatment, as they can vary based on the underlying condition being treated.
- Headache
- Flushing
- Upset stomach
- Vision changes (elaborated below)
- Nasal congestion
- Muscle, back, arm, or leg pain
- Nausea
- Dizziness
- Skin rash
- Diarrhea
- Prolonged painful erection (detailed further below)
There could be additional side effects associated with sildenafil that are not highlighted here. If you are experiencing anything concerning, please reach out to your healthcare provider. In the United States, side effects can also be reported to the FDA through their website or hotline. In Canada, the same can be done through Health Canada’s reporting system.
What are the serious side effects of sildenafil?
Despite being uncommon, certain serious side effects associated with sildenafil warrant immediate attention and action. The following outlines these potential serious reactions, along with recommendations for action should they occur.
Severe Allergic Reactions. Individuals taking sildenafil may experience serious allergic reactions. If symptoms occur, such as the following, discontinue use and seek emergency assistance promptly.
- Breathing difficulties or wheezing
- Rapid heartbeat
- General malaise or fever
- Swollen lymph nodes
- Facial swelling including lips, tongue, or throat
- Difficulty swallowing or tightness of the throat
- Skin rashes, itching, or hives
- Nausea or vomiting
- Lightheadedness or fainting
- Abdominal cramps
- Joint or muscle pain
Painful, Prolonged Erection (Priapism). Sildenafil can potentially cause an erection that is not only prolonged but may also be painful, occurring even in the absence of sexual stimulation. If this symptom is not addressed promptly, it may result in permanent damage to the penile tissue. If you notice any of the following signs of priapism, seek emergency medical treatment without delay.
- Erection lasting beyond four hours
- Erection unrelated to sexual arousal
- Acute pain or tenderness in the penile area
Vision Changes. Sildenafil has been associated with temporary vision disturbances, including a blue tint to vision, color perception anomalies, blurred sight, or photosensitivity. While rare, some patients have reported enduring vision loss. If sudden vision loss occurs in one or both eyes, immediate medical intervention is crucial.
Hearing Loss. There have been reports of sudden hearing loss following sildenafil use, which may include accompanying symptoms such as dizziness or tinnitus. Seek immediate assistance if hearing loss occurs or if there are sudden changes in auditory perception.
Low Blood Pressure (Hypotension). A mild, temporary reduction in blood pressure can occur with sildenafil, with higher susceptibility in individuals with underlying health conditions or those on antihypertensive medications. Should you experience feelings of faintness or dizziness, it is advisable to lie down and inform your healthcare provider immediately if the following symptoms manifest.
- Dizziness or lightheadedness
- Unusual fatigue or weakness
- Fainting episodes
- Disorientation or confusion
Nosebleeds. Use of sildenafil has been linked to an increased incidence of nosebleeds, particularly in individuals on anticoagulant therapy. If you frequently experience nosebleeds while using sildenafil, inform your healthcare provider. In cases of severe or persistent nosebleeds, immediate medical care is warranted.
Warnings & Precautions
Who should not take sildenafil?
Allergies to Ingredients. Patients with known allergies to sildenafil or compounds found in its formulations should refrain from using the medication.
- Sildenafil
- Revatio
- Viagra
- Any specific ingredient within the product dispensed
Your pharmacist can provide detailed information regarding the ingredients in each specific sildenafil product available to them.
Drug Interactions. Patients should avoid taking sildenafil concurrently with certain medications. It is crucial to discuss with your healthcare provider any medications, either prescription or over-the-counter (OTC), vitamins, herbal supplements, or dietary supplements you are currently taking. For detailed information, please see the Interactions section below.
What should I know about sildenafil before taking it?
Only take sildenafil if it has been prescribed to you by a qualified healthcare provider, and always abide by their instructions.
Avoid sharing sildenafil with others, even if they appear to have the same medical concerns, as it may lead to unforeseen adverse effects.
Ensure that sildenafil is stored safely away from children. If the oral liquid form is kept refrigerated, it is vital to prevent access from children who use the refrigerator.
Engaging in sexual activity may impose additional stress on the cardiovascular system, making it potentially hazardous for individuals with certain heart conditions, such as those who have recently experienced a heart attack. Consult your healthcare provider to ascertain whether your heart condition is stable enough for sexual activity. If you experience chest pain, dizziness, or nausea during intercourse, it is imperative to stop and seek immediate medical assistance from your healthcare provider.
Note that sildenafil does not offer protection against sexually transmitted infections, including HIV.
Sildenafil is classified as a phosphodiesterase-5 (PDE-5) inhibitor, a therapeutic class utilized for addressing erectile dysfunction and pulmonary arterial hypertension. It is important to refrain from using more than one PDE-5 inhibitor concurrently. Additional PDE-5 inhibitors include avanafil (Stendra), tadalafil (Cialis), and vardenafil (Levitra).
When measuring sildenafil oral liquid, utilize an accurate measuring device, as household spoons may not provide precise dosing and could lead to misadministration. Consult your pharmacist for a recommended measuring devise.
What should I tell my healthcare provider before taking sildenafil?
Inform your healthcare provider of all health conditions you have and all medications, including OTC products, vitamins, herbal supplements, and dietary aids you are consuming. This information will aid in determining the appropriateness of sildenafil for your situation.
Particularly, be sure to discuss any of the following key health considerations.
Current and Past Health Conditions. Detail any history of the following health issues to your provider:
- Heart conditions, including arrhythmias, angina, or congestive heart failure
- Recent myocardial infarction, stroke, or cardiac procedures within the last six months
- Hypertension or hypotension
- Peyronie's disease or anatomical deformities of the penis
- History of priapism or prolonged erections
- Blood disorders such as sickle cell disease
- Retinal diseases or inherited conditions like retinitis pigmentosa
- Past instances of vision impairment or optic nerve damage
- Conditions elevating the risk of optic nerve issues, such as diabetes mellitus, hyperlipidemia, tobacco use, age over 50, or structural abnormalities recognized during ocular examinations.
- Auditory impairments or issues
- Any bleeding tendencies or disorders
- Peptic ulcers or gastrointestinal bleeding
- Hepatic insufficiencies
- Severe renal dysfunction or requirement for dialysis
- Conditions affecting pulmonary vessels, specifically pulmonary veno-occlusive disease
Pregnancy. The effects of sildenafil during pregnancy are not clearly understood, so it is important to inform your healthcare provider if you are or plan to conceive.
Breastfeeding. Sildenafil may be excreted in breast milk, and it is advisable to discuss your breastfeeding plans with your healthcare provider to determine the safety of continuing sildenafil during this time.
Interactions
Does sildenafil interact with foods or drinks?
Taking sildenafil post intake of a high-fat meal, such as a large burger or fries, may delay its onset of action. It is advisable to consider meal timing in relation to medication scheduling.
Your healthcare provider may suggest limiting or entirely avoiding grapefruit consumption while on sildenafil treatment. Grapefruit can elevate the levels of sildenafil in your bloodstream, thus increasing the chances of experiencing side effects. Close monitoring of dietary intake may be necessary for optimal efficacy and safety.
Current evidence does not indicate any significant interactions between sildenafil and moderate alcohol consumption; however, excessive alcohol may hinder the drug's effectiveness.
Does sildenafil interact with other medicines (drug interactions)?
Maintaining open communication with your healthcare provider about all medications, including OTC items, vitamins, and herbal remedies, is essential. This practice ensures a comprehensive understanding of potential drug interactions and overall treatment safety.
Be sure to specifically mention the following categories of medications if you are using any of the following prior to commencing sildenafil therapy:
- Nitrate medications like nitroglycerin or other preparations aiding in angina management or illicit substances like amyl nitrite
- Guanylate cyclase stimulators such as riociguat or vericiguat
- Alpha-blockers used for hypertension or prostate issues
- Antihypertensive agents like amlodipine
- Bosentan for pulmonary arterial hypertension
- Protease inhibitors for HIV treatment
- Antifungal agents like ketoconazole or itraconazole
- Macrolide antibiotics like erythromycin or clarithromycin
- Other medications prescribed for erectile dysfunction or pulmonary hypertension
Additionally, some medications may influence the systemic concentration of sildenafil; hence, inform your healthcare provider about all medicines you are currently using or have used in recent times.
This list may not encompass all medications that may interact with sildenafil. Always seek clarification and guidance from your healthcare provider.
Does 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?
If an overdose is suspected, or if you or someone else has ingested an excessive amount of sildenafil, it is crucial to seek immediate medical assistance by calling emergency services or contacting a Poison Control center without delay for guidance.
What should I do if I miss a dose of sildenafil?
Erectile Dysfunction. In instances where sildenafil is prescribed solely for the treatment of erectile dysfunction, it is to be taken on an as-needed basis. Follow your healthcare provider's instructions, typically within a window of 30 minutes to four hours before anticipated sexual activity. Avoid taking multiple or extra doses for missed opportunities.
Pulmonary Arterial Hypertension. For this condition, sildenafil is generally dosed three times daily as per medical guidance. If you miss a dose, take it promptly upon realization. However, if your next scheduled dose is imminent, skip the missed dose; do not take double doses under any circumstances. Should you have uncertainty about the missed dose, consult your healthcare provider for appropriate advice.