Sildenafil (Viagra, Revatio): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD
What is sildenafil used for?
Sildenafil is commonly used for the following conditions.
- Erectile dysfunction, which is defined as a situation wherein you experience difficulty in either achieving or sustaining an erection suitable for sexual performance
- Pulmonary arterial hypertension, characterized by elevated blood pressure within the blood vessels conveying blood from your heart toward your lungs, making activities increasingly difficult
Additionally, sildenafil may be prescribed for other conditions as specified by your healthcare provider based on your medical history and specific health requirements.
How does sildenafil work (mechanism of action)?
Sildenafil functions by inhibiting a specific enzyme known as PDE5, which plays a crucial role in the regulation of blood flow. In cases of erectile dysfunction, it enhances blood circulation to the penis upon sexual arousal, thus facilitating the ability to achieve and maintain an erection. Meanwhile, for individuals with pulmonary arterial hypertension, sildenafil helps to relax and widen the blood vessels within the lungs, subsequently reducing pressure within these vessels and alleviating stress on the heart muscle.
How is sildenafil supplied (dosage forms)?
Brands and alternative names
- Viagra
- Revatio
Dosage forms and strengths available
- 10 mg/mL powder meant for oral suspension
- 20 mg, 25 mg, 50 mg, and 100 mg oral tablets
Moreover, sildenafil can also be administered in an injectable form, typically administered by a healthcare professional in clinical settings such as a hospital.
How should I store sildenafil?
Oral Tablet. Sildenafil oral tablets need to be stored at room temperature, ideally maintained between 68°F to 77°F (20°C to 25°C). It's permissible for them to be exposed to temperatures ranging from 59°F to 86°F (15°C to 30°C) for brief intervals, such as during transport. Always keep in a cool, dry location away from moisture.
Oral Liquid. When it comes to sildenafil oral liquid, it should also be kept at room temperature, below 86°F (30°C) or in the refrigerator between 36°F to 46°F (2°C to 8°C). It must not be frozen, and any unused liquid must be discarded 60 days after being mixed by a pharmacist or healthcare provider.
Injection Liquid. The injectable form of sildenafil is typically administered by healthcare professionals in a hospital or clinic setting; hence, it is not stored at home.
Side Effects
What are the most common side effects of sildenafil?
The most frequently reported side effects associated with sildenafil are noted below. These side effects can differ based on the specific condition being treated. It is essential to inform your healthcare provider if you are experiencing any of these side effects that are troubling you.
- Headache
- Flushing
- Upset stomach
- Changes in vision (further details to follow)
- Nasal congestion
- Muscle, back, arm, or leg pain
- Nausea
- Dizziness
- Rash
- Diarrhea
- Prolonged, painful erection (details are below)
There might be additional side effects that are not listed here. If you suspect you are experiencing a side effect from sildenafil, reach out to your healthcare provider without delay. In the United States, side effects can be reported to the FDA through www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, individuals can report side effects to Health Canada via www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of sildenafil?
Although less common, sildenafil may lead to serious side effects that are outlined below, along with suggested actions if they occur.
Severe Allergic Reactions. Sildenafil has the potential to initiate serious allergic reactions, which can be life-threatening. If you experience any of the following symptoms indicative of a severe allergic reaction, discontinue use of sildenafil immediately and seek urgent medical assistance.
- Difficulty breathing or wheezing
- Rapid heartbeat
- Fever or feeling unwell
- Swelling of the lymph nodes
- Swelling in the face, lips, mouth, tongue, or throat
- Trouble swallowing or a feeling of throat tightness
- Itching, skin rash, or the appearance of small red bumps on the skin known as hives
- Nausea or vomiting
- Dizziness, lightheadedness, or fainting spells
- Stomach cramps
- Joint pain
Painful, Prolonged Erection (Priapism). In some instances, sildenafil may result in an unwanted erection that is not only persistent and painful but may occur even without sexual stimulation. Should priapism not be treated promptly, it could lead to permanent damage to the penis. If you experience any of the following signs of priapism, stop taking sildenafil and immediately seek emergency medical care.
- Erection lasting for more than four hours
- Erection not linked to sexual arousal
- Pain or tenderness in the penile region
Vision Changes. Sildenafil may induce mild and temporary alterations in vision, including seeing a blue tint, unusual color perception, blurred vision, or heightened sensitivity to light. Though it is rare, some individuals have experienced permanent vision loss. If you notice sudden vision loss in one or both eyes, stop using sildenafil immediately and seek medical help.
Hearing Loss. Cases of sudden hearing loss have been reported as a result of taking sildenafil. This may coincide with symptoms such as dizziness and ringing in the ears. If you experience sudden hearing loss or an unexpected difficulty hearing, discontinue sildenafil usage and seek immediate medical attention.
Low Blood Pressure (Hypotension). Another potential side effect of sildenafil is a temporary and mild decrease in blood pressure. Individuals with specific health conditions or those on blood pressure medications may be at an elevated risk. If you experience sensations of faintness or dizziness, it is advisable to lie down. Inform your healthcare provider right away if you experience any of the following symptoms associated with low blood pressure.
- Dizziness or feeling lightheaded
- Feeling excessively weak or fatigued
- Fainting episodes
- Experiencing confusion
Nosebleeds. Individuals taking sildenafil might also experience nosebleeds. The risk of this side effect may be heightened if you are concurrently using blood-thinning medications. Speak to your healthcare provider if you frequently experience nosebleeds while on sildenafil. In the event of a severe nosebleed that does not cease after applying pressure, you should seek immediate medical attention.
Warnings & Precautions
Who should not take sildenafil?
Allergies to Ingredients. Individuals with a known allergy to any of the following substances should avoid taking sildenafil.
- Sildenafil itself
- Revatio
- Viagra
- Any of the ingredients found in the specific formulation provided
Your pharmacist can provide you with detailed information regarding all of the ingredients contained in the specific sildenafil products they have available.
Drug Interactions. It is crucial to avoid taking sildenafil in conjunction with certain other medications. Prior to initiating sildenafil therapy, disclose to your healthcare provider any prescription or over-the-counter (OTC) medications, vitamins, minerals, herbal products, and other dietary supplements that you are currently utilizing. Please refer to the Interactions section for comprehensive information.
What should I know about sildenafil before taking it?
You should only take sildenafil if it has been prescribed specifically for you by a qualified healthcare provider. It is imperative to adhere to the prescribed directions.
Sharing sildenafil with others, even if they are experiencing similar symptoms as you, is discouraged as it may result in adverse effects for them.
Ensure that sildenafil is kept out of children’s reach. In cases where sildenafil oral liquid is stored in a refrigerator, it is advisable to keep it away from children who might have access to the refrigerator.
Engaging in sexual activity can impose additional stress on your heart, which may be unsafe for individuals with specific health conditions, such as those who have recently experienced a heart attack. Consult with your healthcare provider to assess if your heart is in a suitable condition for sexual activity. Should you experience chest pain, dizziness, or nausea during sexual activity, it is crucial to stop and immediately contact your healthcare provider.
Sildenafil does not provide protection against sexually transmitted infections, including HIV.
Sildenafil is classified within a category of medications known as phosphodiesterase-5 (PDE-5) inhibitors, which are utilized for the treatment of erectile dysfunction or pulmonary arterial hypertension. You should refrain from taking more than one PDE-5 inhibitor medication simultaneously. This category includes avanafil (Stendra), sildenafil (Viagra, Revatio, and other variants), tadalafil (Cialis and related products), and vardenafil (Levitra, Staxyn).
To ensure proper dosage, employ an accurate measuring device for sildenafil oral liquid. A standard household spoon is not a reliable measuring tool and may lead to incorrect dosing. Consult your pharmacist for recommendations on suitable measuring devices.
What should I tell my healthcare provider before taking sildenafil?
Inform your healthcare provider about all existing health conditions, as well as any prescription or over-the-counter (OTC) medications, vitamins, minerals, herbal products, and other supplements you might be taking. This information is pivotal in determining if sildenafil is appropriate for you.
Specifically, ensure that you discuss any of the following conditions with your healthcare provider.
Current and Past Health Conditions. Make sure to communicate with your healthcare provider if you have any of these health concerns.
- Cardiovascular issues, including irregular heart rhythms, angina, or heart failure
- Having suffered a heart attack, stroke, or heart surgery in the past six months
- Experiencing low blood pressure
- Having high blood pressure that remains elevated despite treatment
- Conditions such as Peyronie's disease, which results in abnormal curvature of the penis
- History of prolonged erections exceeding four hours
- Presence of blood disorders, including sickle cell anemia
- An inherited condition affecting the eyes known as retinitis pigmentosa
- Vision loss or issues relating to the optic nerve, which transmits visual information from the eyes to the brain
- Health conditions impacting the optic nerve, such as diabetes, high cholesterol, older age, or having a "crowded disc" observed during an eye exam
- Auditory problems
- Disorders leading to bleeding
- History of stomach ulcers
- Liver dysfunction or disease
- Severe kidney impairment or individuals undergoing dialysis
- Pulmonary veno-occlusive disease, a condition characterized by blockage in the lung blood vessels
Pregnancy. There is insufficient data to ascertain the effects of sildenafil on pregnancy or whether it could potentially harm an unborn child. Make sure to inform your healthcare provider if you are pregnant or planning to become pregnant.
Breastfeeding. Sildenafil can be excreted in breast milk. Notify your healthcare provider if you are currently breastfeeding or plan to initiate breastfeeding. Your healthcare provider will provide guidance on whether sildenafil can be taken safely while breastfeeding.
Interactions
Does sildenafil interact with foods or drinks?
When sildenafil is taken following the consumption of a high-fat meal, such as a greasy burger and fries, the onset of its action may be delayed.
Your healthcare provider might suggest avoiding grapefruit or its juice while on sildenafil, as it can elevate the levels of sildenafil in your bloodstream, thereby increasing the risk of side effects.
No specific interactions between sildenafil and alcoholic beverages have been identified.
Does sildenafil interact with other medicines (drug interactions)?
It is essential to disclose all prescription and over-the-counter (OTC) medications, vitamins, minerals, herbal products, and dietary supplements you are currently taking to your healthcare provider.
You should especially mention if you are using any of the following prior to initiating sildenafil treatment.
- Nitrates, such as nitroglycerin (Nitro-Dur, Nitrostat, and others) or isosorbide, commonly prescribed for chest pain associated with cardiovascular disease, or recreational drugs like amyl nitrite (“poppers”)
- Guanylate cyclase stimulators like riociguat (Adempas), aimed at treating high blood pressure in the lungs, or vericiguat (Verquvo), intended for managing certain heart failure types
- Alpha-blockers, including alfuzosin (Uroxatral), doxazosin (Cardura), dutasteride, prazosin (Minipress), silodosin (Rapaflo), tamsulosin (Flomax), or terazosin (Hytrin), which are often used for high blood pressure and enlarged prostate-related urinary issues
- Blood pressure medications such as amlodipine (Norvasc)
- Bosentan (Tracleer), utilized for managing pulmonary arterial hypertension
- Protease inhibitors like ritonavir (Norvir), which are commonly used for treating HIV
- Fungal infection treatments like ketoconazole or itraconazole (Sporanox, Tolsura)
- Antibiotics such as erythromycin (Ery-Tab, and others) or clarithromycin (Biaxin), used for bacterial infections
- Any other medications prescribed for erectile dysfunction or pulmonary arterial hypertension
Other medications may potentially alter the levels of sildenafil in your system. It is important to inform your healthcare provider of all medications you are currently taking or have recently used.
This list may not be exhaustive and other medications that interact with sildenafil may exist. Therefore, always verify information 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 that you or someone else ingests an excessive amount of sildenafil, it is crucial to seek medical assistance immediately by calling 911 or reaching out to a Poison Control center at 800-222-1222.
What should I do if I miss a dose of sildenafil?
Erectile Dysfunction. In this instance, sildenafil is typically used on an as-needed basis. It is expected to be taken as directed by your healthcare provider, often administered between 30 minutes to four hours before planned sexual activity. Avoid taking double or additional doses.
Pulmonary Arterial Hypertension. For this condition, sildenafil is usually taken as per the healthcare provider's instruction, often three times a day. If you miss a dose, consume it as soon as you remember. If you are close to your next scheduled dose, skip the missed dose and proceed with the upcoming dose only. Consult your healthcare provider for clarity regarding missed doses. Steer clear of taking double or extra doses.