Sildenafil vs Tadalafil: What's the difference?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Do not change your dose or stop taking this medicine on your own.

• Sildenafil is available in various dosage forms beyond oral tablets.
• Revatio is available as an injectable solution for intravenous use in PAH.
• The IV dose is 10mg administered three times a day as a bolus injection.
• There is also an oral suspension formulation of Revatio for pediatric use.
• A topical gel formulation of sildenafil has been investigated for ED.
• Orally disintegrating tablets and fast-dissolving films are also in development.
• Different formulations aim to improve onset of action or patient convenience.
• The bioavailability and pharmacokinetics differ between formulations.
• Only the oral tablet and IV solution are currently widely approved and available.
• Patients should never switch formulations without consulting their doctor.
• The dose and dosing frequency are specific to each formulation and indication.

Take sildenafil tablet or oral suspension 3 times a day, about 4 to 6 hours apart.

Country	Prescription Requirement	Over-the-Counter Availability	Regulatory Body
USA	Yes	No	FDA
UK	Yes	No	MHRA
Canada	Yes	No	Health Canada
Australia	Yes	No	TGA
India	Yes (in some states)	Some brands available OTC	CDSCO

Take at approximately the same times every day. Sildenafil oral suspension will be mixed for you by your pharmacist. Do not mix with other medicines or flavorings.

Patient Group	Recommended Dose	Frequency of Use	Notes
First-time users	20 mg	Once per day	Take 30-60 min before activity
Experienced users	May increase to 50 mg	As needed	Under medical supervision
Elderly patients	20 mg or lower	As needed	Start with lowest dose
Patients on other medications	Consult doctor	Varies	Adjust dose accordingly

Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon). When sildenafil is used for ED, it is used as needed, so you are not likely to miss a dose. If you are taking sildenafil for PAH and you miss a dose, take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time. If you take too much sildenafil, call your doctor or go to the nearest hospital emergency room.

Further information

If you need emergency medical care for a heart problem, it will be important for your healthcare provider to know when you last took sildenafil. Stop sexual activity and get medical help right away if you get symptoms such as chest pain, dizziness, or nausea during sex. Sexual activity can put an extra strain on your heart, especially if your heart is already weak from a heart attack or heart disease. Sildenafil does not protect you or your partner from getting sexually transmitted diseases, including Human Immunodeficiency Virus (HIV). Sildenafil may cause low blood pressure, which may cause you to feel faint or dizzy.

2.5 Dosage Adjustments in Special Populations

Lie down if you feel faint or dizzy. Tell your doctor if you get more short of breath after you start sildenafil. More shortness of breath than usual may be due to your underlying medical condition. Do not take Viagra while also taking Revatio. Tell your healthcare provider if you have any side effect that bothers you or does not go away.

Related treatment guides

These are not all of the possible side effects of sildenafil. Have allergies to sildenafil, Viagra, Revatio, Vybrique, or any of the ingredients in the sildenafil formulation you are taking Take other medicines for pulmonary arterial hypertension, such as riociguat (Adempas) Take other medicines for pulmonary arterial hypertension, such as riociguat (Adempas) Take other medicines that lower your blood pressure, such as nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, and some recreational drugs that also contain nitrates, such as "poppers". To make sure sildenafil is safe for you, tell your healthcare provider about all your medical conditions, including if you have: Or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure Had heart surgery within the last 6 months Low blood pressure, or high blood pressure that is not controlled A physical deformity of the penis (such as Peyronie's disease) Been told you should not have sexual intercourse for health reasons and you are a male Had an erection that lasted for more than 4 hours Problems with your blood cells, such as sickle cell anemia, multiple myeloma, or leukemia Retinitis pigmentosa, a rare genetic (runs in families) eye disease Ever had severe vision loss, including an eye problem called non-arteritic anterior ischemic optic neuropathy (NAION) Kidney problems or are having kidney dialysis Are pregnant or intending to become pregnant (for patients with PAH) Are breastfeeding or intending to breastfeed (for patients with PAH). Sildenafil for ED is not approved for males <18 years old. Sildenafil is not expected to harm an unborn baby. Drinking alcohol with sildenafil can cause side effects. Grapefruit juice and products may interact with sildenafil, leading to unwanted side effects. Avoid using any other medicines to treat impotence, such as alprostadil or yohimbine, without first talking to your doctor. Tell your healthcare provider about all the medicines you take, including prescription and over-the-countermedicines, vitamins, and herbal supplements. Sildenafil may affect the way other medicines work, and other medicines may affect the way sildenafil works, causing side effects. Especially tell your healthcare provider if you take: Nitrates for chest pain or heart problems.

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This includes nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate. Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers").

Overdose/Missed Dose

Tell your doctor if you are pregnant or plan to become pregnant. Women with pulmonary arterial hypertension should not stop taking sildenafil without talking to their doctor if they discover they are pregnant. It is not known whether sildenafil passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breastfeeding a baby. Women with pulmonary arterial hypertension should not stop taking sildenafil without talking to their doctor.

5.5 Hypotension when Co-administered with Alpha-blockers or Anti-hypertensives

Take sildenafil oral tablets exactly as your healthcare provider tells you to take it. Your healthcare provider will tell you how much to take and when to take it. Your healthcare provider may change your dose if needed. You may take sildenafil between 30 minutes to 4 sildenafil citrate 100 mg hours before sexual activity if needed. If you take sildenafil after a high-fat meal (such as a cheeseburger and fries), sildenafil may take a little longer to start working.

Dosage Forms and Strengths

If you accidentally take too much sildenafil, call your doctor or go to the nearest hospital emergency room right away. Sildenafil can help you have an erection when sexual stimulation occurs. An erection will not occur just by taking a pill. During sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. You could be having a serious side effect of sildenafil. Taking sildenafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure Alpha-blockers are sometimes prescribed for prostate problems orhigh blood pressure. In some patients, the use of sildenafil with alpha-blockers can lead to a drop in blood pressure or fainting Other drugs to treat high blood pressure or a prostate disorder Medicines to treat HIV, such as protease inhibitors, such as ritonavir and saquinavir Some types of oral antifungal medicines, such as ketoconazole and itraconazole Some types of antibiotics, such as erythromycin Other medicines that treat high blood pressure Medicines or treatments for ED, such as avanafil (Stendra), tadalafil (Cialis), or vardenafil (Levitra).

What other drugs will affect sildenafil?

Some medicines can cause unwanted or dangerous effects when used with sildenafil. Tell your doctor about all your current medicines, especially riociguat (Adempas). The most common side effects of sildenafil tablets for ED are: Abnormal vision, such as changes in color vision (such as having a blue color tinge) andblurred vision The most common side effects of sildenafil oral film for ED are: Abnormal vision, such as changes in color and blurred vision The most common side effects of sildenafil tablets/ oral suspension, and injection for PAH are: Sildenafil can cause the following serious side effects. If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis.

Common Side Effects

Sildenafil can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. This has occurred in a small number of people taking sildenafil, most of whom also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoked or were over 50 years old. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION). Stop taking sildenafil and call your healthcare provider right away if you havesudden vision loss in one or both eyes. Some people may also have ringing in their ears (tinnitus) or dizziness.

8.4 Pediatric Use

If you have these symptoms, stop taking sildenafil and contact a doctor right away. In addition, heart attack, stroke, irregular heartbeats, and death have happened rarely in people taking sildenafil. Most, but not all, of these people had heart problems before taking this medicine. It is not known if sildenafil caused these problems. Tell all your healthcare providers that you take sildenafil. Tell your doctor about all other medications you use for erectile dysfunction. Ask your healthcare provider or pharmacist for a list of these medicines if you are not sure. Keep a list of them to show to your healthcare provider and pharmacist when you get a new medicine. Other drugs may interact with sildenafil, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here. Store sildenafil tablets and oral film at room temperature, between 20°C and 25°C (68°F and 77°F).

What special dietary instructions should I follow?

Take sildenafil oral film (Vybrique) exactly as your healthcare provider tells you to take it. Your healthcare provider will tell you how much sildenafil to take and when to take it. Take sildenafil by mouth about 1 hour before sexual activity. You may take sildenafil between 30 minutes and 4 hours before sexual activity if needed. Do not take more than once a day.

What Are the Available Sildenafil Dosages?

If you take too much sildenafil, call your healthcare provider or go to the nearest hospital emergency room right away. Do not remove the film from the pouch unless ready for immediate use. Do not handle the oral film with wet hands. See the Vybrique Prescribing Information for more information about how to take sildenafil oral film. Take sildenafil exactly as it was prescribed for you. Store sildenafil reconstituted oral suspension below 30°C (86°F) or in a refrigerator between 2°C to 8°C (36°F to 46°F).

• Sildenafil interacts with nitrate medications, causing dangerous drops in blood pressure.
• Store sildenafil in a cool, dry place away from children.
• 20mg is often recommended as a starting dose for ED treatment.
• Food, especially high-fat meals, can delay its onset of action.
• Regular use can improve erectile response over time if prescribed.

Throw away the reconstituted oral suspension after 60 days.

Drug Class	Interaction Effect	Recommendation
Nitrates	Severe hypotension	Avoid combination
Alpha-blockers	Additive blood pressure lowering effect	Use with caution
CYP3A4 inhibitors (e.g., ketoconazole)	Increased sildenafil levels	Dose adjustment may be necessary
Antihypertensives	Enhanced blood pressure reduction	Monitor blood pressure
Grapefruit juice	Increased plasma concentration	Avoid during treatment

Active ingredient: sildenafil citrateInactive ingredients: dextrose and water for injection. Contains no ingredients made from gluten-containing grain (eg, wheat, barley, or rye).