Sildenafil (Viagra, Revatio): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD
What is sildenafil used for?
Sildenafil is commonly used for the following conditions and may also be prescribed for additional health issues as deemed appropriate by your healthcare professional.
- Erectile dysfunction, which is characterized by difficulties in achieving or maintaining a satisfactory erection during sexual activity, significantly impacting quality of life.
- Pulmonary arterial hypertension, a serious condition characterized by elevated blood pressure in the arteries supplying blood to the lungs, leading to various complications if left untreated.
There are other potential uses for sildenafil that a healthcare provider might consider, based on individual patient needs and medical history.
How does sildenafil work (mechanism of action)?
The therapeutic effects of sildenafil are achieved through its mechanism of action, which involves the inhibition of the enzyme phosphodiesterase type 5 (PDE5). By blocking PDE5, sildenafil promotes relaxation of blood vessels, which enhances blood flow in specific areas. In patients with erectile dysfunction, this increased blood flow occurs in the penis upon sexual arousal, facilitating the ability to achieve and sustain an erection. In the context of pulmonary arterial hypertension, sildenafil acts to relax pulmonary blood vessels, effectively reducing blood pressure in the lungs and easing the 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
For patients requiring more immediate intervention or unable to take oral forms, sildenafil can also be given via injection, typically administered by healthcare professionals within a clinical setting under strict medical supervision.
How should I store sildenafil?
Oral Tablet. To ensure the efficacy of sildenafil oral tablets, they should be kept at room temperature, ideally between 68 F to 77 F (20 C to 25 C). Temporary exposure to slightly higher or lower temperatures (between 59 F to 86 F or 15 C to 30 C) may be acceptable during transport. Always store in a cool, dry location, away from direct sunlight and excessive moisture.
Oral Liquid. Proper storage of sildenafil oral liquid is crucial for maintaining its integrity, so it should be kept at room temperature, preferably below 86 F (30 C), or can be refrigerated at temperatures ranging from 36 F to 46 F (2 C to 8 C). Freezing is not recommended, and any unused liquid should be discarded after 60 days post-mixing by a qualified pharmacist or healthcare professional.
Injection Liquid. Sildenafil in injectable form is designed for administration by trained healthcare providers in hospitals or clinics, and therefore should not be stored or administered by patients at home.
Side Effects
What are the most common side effects of sildenafil?
As with any medication, sildenafil may cause side effects, some of which are relatively common and may vary in frequency and intensity depending on the condition being treated. It’s important to notify your healthcare provider if any of these side effects become bothersome or persistent.
- Headache
- Flushing
- Upset stomach
- Vision changes (see below)
- Nasal congestion
- Pain in your muscles, back, arms, or legs
- Nausea
- Dizziness
- Rash
- Diarrhea
- Painful, prolonged erection (see below)
It is worth noting that there could be additional side effects associated with sildenafil that are not explicitly mentioned here. If you suspect that you are experiencing a side effect from this medication, it is critical to reach out to your healthcare provider for further guidance. In the United States, side effects can also be reported to the FDA via www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can contact Health Canada at www.health.gc.ca/medeffect or call 866-234-2345.
What are the serious side effects of sildenafil?
While serious side effects are not common, it is vital to be aware of them for timely intervention. Below are some of the serious side effects associated with sildenafil, along with recommended actions if they occur.
Severe Allergic Reactions. This medication can provoke allergic reactions in susceptible individuals, which can become severe. If you experience any of the following signs of a severe allergic response, discontinue sildenafil and seek immediate medical attention:
- Breathing problems or wheezing
- Racing heart
- Fever or feeling generally unwell
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Difficulty swallowing or sensations of throat tightness
- Itching, rash, or hives
- Nausea or vomiting
- Dizziness, lightheadedness, or fainting
- Stomach cramps
- Joint pain
Painful, Prolonged Erection (Priapism). This condition may present as a painful and prolonged erection, which can occur without any form of sexual stimulation. It is crucial that priapism is treated promptly to avoid lasting damage. If you experience any of the following indicative symptoms, seek emergency medical assistance immediately:
- Erection lasting more than four hours
- Erection not related to sexual arousal
- Pain or tenderness in the penis
Vision Changes. You may experience mild, temporary visual disturbances while taking sildenafil; these can include seeing a blue tint, abnormal color perception, blurred vision, or heightened sensitivity to light. Although rare, some users have reported instances of permanent vision loss. If you experience sudden vision loss in one or both eyes, discontinue sildenafil and seek immediate medical help.
Hearing Loss. There have been instances of sudden hearing loss linked to sildenafil use, often accompanied by dizziness and ringing in the ears. Immediately discontinue use and consult your healthcare provider if you experience sudden changes in hearing or difficulty hearing.
Low Blood Pressure (Hypotension). Sildenafil may cause a temporary drop in blood pressure, which can pose a risk to individuals with specific health conditions or who are taking medications for blood pressure management. If you feel faint or dizzy, lying down can help. Report any of the following symptoms to your healthcare provider promptly:
- Dizziness or feeling faint
- Unexplained fatigue or weakness
- Fainting spells
- Confusion or disorientation
Nosebleeds. Nosebleeds may occur while taking sildenafil, particularly if you are on blood-thinning medications. If you experience frequent or severe nosebleeds, it's important to consult with your healthcare provider. Should a nosebleed continue despite applying pressure, immediate medical assistance is necessary.
Warnings & Precautions
Who should not take sildenafil?
Allergies to Ingredients. Individuals who have known allergies to sildenafil or any of the components in these medications should refrain from taking sildenafil.
- Sildenafil
- Revatio
- Viagra
- Any specific ingredients in the formulation provided
Consult your pharmacist for information regarding the contents of the specific sildenafil products available at the pharmacy.
Drug Interactions. It is crucial to avoid taking sildenafil concurrently with certain medications. Prior to initiating sildenafil, inform your healthcare provider of all prescription and over-the-counter (OTC) drugs, as well as vitamins and herbal supplements you may be using. Detailed information on interactions can be found in the Interactions section for more information.
What should I know about sildenafil before taking it?
Do not use sildenafil unless your healthcare provider has prescribed it for you. Adhere strictly to their dosing instructions.
Avoid sharing your sildenafil medication with anyone else, even if they display similar symptoms. Doing so can potentially harm others.
Store sildenafil out of the reach of children. In the event that you keep sildenafil oral liquid in a refrigerator, ensure it is stored away from the reach of children who may access the refrigerator.
Engaging in sexual activity can impose additional stress on the heart, which may not be advisable for individuals with certain medical histories, such as those who have recently experienced a heart attack. Discuss with your healthcare provider whether your cardiovascular health permits sexual activity. Should you experience chest discomfort, dizziness, or nausea while engaging in sexual activity, stop immediately and contact your healthcare provider.
It is essential to understand that sildenafil does not offer protection against sexually transmitted infections, including HIV.
As a phosphodiesterase-5 (PDE-5) inhibitor, sildenafil is part of a class of medications employed to treat erectile dysfunction and pulmonary arterial hypertension. Patients should not use more than one PDE-5 inhibitor concurrently. Other medications in this class include avanafil (Stendra), tadalafil (Cialis), and vardenafil (Levitra).
When measuring your dose of sildenafil oral liquid, use a precise measuring device. Household spoons lack precision and can lead to inaccurate 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 existing health conditions and any medications you are currently taking, whether they are prescription or over-the-counter, as well as any vitamins and supplements. This will assist your healthcare provider in making an informed decision regarding the appropriateness of sildenafil use for you.
Of particular importance is the disclosure of any of the following:
Current and Past Health Conditions. Communicate with your healthcare provider if you have recently experienced any of the following health issues:
- Cardiac problems, including arrhythmias, chest pain, or heart failure
- Recent heart attack, stroke, or cardiac surgery
- Experiencing low blood pressure
- Persistently high blood pressure despite medications
- Peyronie's disease, which involves abnormal curvature of the penis
- History of prolonged erections lasting over four hours
- Blood disorders, such as sickle cell anemia
- Genetic eye diseases like retinitis pigmentosa
- Previous vision loss or issues related to the optic nerve
- Conditions increasing the likelihood of optic nerve issues, including diabetes or high cholesterol
- Hearing issues or past hearing loss
- Bleeding disorders or tendencies
- Peptic ulcers
- Any liver or severe kidney conditions
- Pulmonary veno-occlusive disease, characterized by blockages in the lung's blood vessels
Pregnancy. The effects of sildenafil on pregnancy or potential risks to an unborn child are not fully understood. Notify your healthcare provider should you become pregnant or plan to during treatment.
Breastfeeding. As sildenafil can be transmitted into breast milk, inform your healthcare provider if you are breastfeeding or intend to breastfeed. They will provide guidance on the safety of continuing sildenafil under these circumstances.
Interactions
Does sildenafil interact with foods or drinks?
When taking sildenafil, consuming a high-fat meal—like a cheeseburger and fries—before administration may delay its onset of action, as high-fat foods can hinder the absorption of the medication.
Your healthcare provider may advise you to limit or avoid grapefruit products during sildenafil treatment, as grapefruit and its juice can increase sildenafil concentrations in your bloodstream, thereby elevating the risk for potential side effects.
As of now, no significant interactions have been reported between sildenafil and alcohol intake.
Does sildenafil interact with other medicines (drug interactions)?
It is essential to keep your healthcare provider informed regarding any medications being taken, whether they are prescribed or obtained over-the-counter, along with any vitamins, minerals, herbal remedies, and supplements. This information will enable your healthcare provider to determine any potential interactions.
Specifically, be sure to discuss any current usage of the following medications prior to starting sildenafil:
- Nitrates, including nitroglycerin (various forms like Nitro-Dur, Nitrostat) or isosorbide, often prescribed for chest pain associated with heart disease, or illicit substances like amyl nitrite (“poppers”)
- Guanylate cyclase stimulators, such as riociguat (Adempas) or vericiguat (Verquvo) used for pulmonary arterial hypertension or heart failure
- Alpha-blockers, such as alfuzosin (Uroxatral), doxazosin (Cardura), or tamsulosin (Flomax), which are utilized for managing hypertension or urinary symptoms from prostate enlargement
- Antihypertensive medications, for example, amlodipine (Norvasc)
- Bosentan (Tracleer), a treatment option for pulmonary arterial hypertension
- Protease inhibitors, including ritonavir (Norvir) typically used in HIV therapy
- Antifungal agents such as ketoconazole or itraconazole (Sporanox)
- Antibiotics like erythromycin or clarithromycin (Biaxin)
- Any other medicines prescribed for erectile dysfunction or pulmonary arterial hypertension
Some medications can also alter the systemic levels of sildenafil in your body. It’s crucial to inform your healthcare provider about all the medications you are currently taking or have recently used.
This list may not capture all medications that may interact with sildenafil; always verify with your healthcare provider for comprehensive information.
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 you suspect an overdose of sildenafil has occurred, it is critical to seek medical assistance immediately by calling emergency services or a poison control center at 800-222-1222. Take this situation seriously, as overdose can lead to severe health consequences.
What should I do if I miss a dose of sildenafil?
Erectile Dysfunction. For this indication, sildenafil is prescribed on an as-needed basis. It is best to take it as your healthcare provider suggests, typically 30 minutes to four hours before planned sexual activity. Avoid taking multiple doses at once or exceeding the recommended frequency.
Pulmonary Arterial Hypertension. In this context, sildenafil is generally administered three times daily according to your healthcare provider's directions. If a dose is missed, take it promptly when you remember. However, if it's nearly time for your next scheduled dose, skip the missed dose and proceed with your regular dosing schedule. Always consult with your healthcare provider if you have any uncertainties regarding managing a missed dose, and do not double up on doses.