Sildenafil is the nonproprietary name of an active pharmaceutical drug in the phosphodiesterase type 5, or PDE5, inhibitor class. Many sildenafil medicines use the citrate salt, sildenafil citrate, while the pharmacologically active drug is referred to simply as sildenafil. It is a prescription medicine in the United States and appears in both branded and generic products.
Sildenafil is best known through two major product contexts: erectile dysfunction and pulmonary arterial hypertension. Viagra is a branded sildenafil product associated with erectile dysfunction, while Revatio is a sildenafil product family labeled for pulmonary arterial hypertension. The same active drug therefore appears in products with different indications, strengths, dosage forms and prescribing frameworks.
This page provides the high-level map needed to understand sildenafil as a medicine: what the name means, its drug class, major approved uses, brands, formulations, basic mechanism, pharmacokinetics and safety context. Each of those subjects is linked to a dedicated page when deeper detail would otherwise duplicate another part of the site.
Sildenafil is the nonproprietary name of the pharmacologically active drug rather than the name of one specific brand or finished product. It belongs to the PDE5 inhibitor class, a group of medicines defined by inhibition of phosphodiesterase type 5.
That distinction between active drug and finished product is important. A medicine containing sildenafil also has a particular dosage form, strength, manufacturer, labeling and sometimes a proprietary brand name. Those product-level characteristics can change while sildenafil remains the active pharmaceutical ingredient.
This is why the word sildenafil can appear on generic erectile-dysfunction tablets as well as within branded products such as Viagra and Revatio. For a more detailed vocabulary map, see sildenafil terminology.
| Term | Meaning |
|---|---|
| Sildenafil | Nonproprietary name of the active drug |
| PDE5 inhibitor | Pharmacological class to which sildenafil belongs |
| Brand | Proprietary identity of a specific sildenafil-containing product |
| Generic product | Approved medicine marketed under the nonproprietary drug identity rather than the original brand |
| Dosage form | Physical form in which a particular sildenafil product is supplied |
The terms sildenafil and sildenafil citrate are closely related but describe slightly different pharmaceutical concepts. Sildenafil refers to the active drug moiety, while sildenafil citrate is the citrate salt form used in many sildenafil medicine products.
For example, Viagra tablets contain sildenafil citrate in amounts equivalent to specified quantities of sildenafil. The citrate salt helps define the pharmaceutical substance used to manufacture the product, but it does not represent a second PDE5-inhibitor drug with a different core mechanism.
In general medical discussion, the shorter term sildenafil is used when referring to the drug's pharmacology, uses or systemic exposure. The salt relationship is explained more fully on sildenafil citrate.
| Term | What It Describes |
|---|---|
| Sildenafil | Active drug moiety |
| Sildenafil citrate | Citrate salt form used in pharmaceutical products |
| Different PDE5 mechanisms? | No |
Sildenafil is a phosphodiesterase type 5 inhibitor. PDE5 is an enzyme that breaks down cyclic guanosine monophosphate, or cGMP, in tissues where this signaling pathway is active. By inhibiting PDE5, sildenafil changes the persistence of cGMP signaling rather than creating the upstream signal itself.
Tadalafil, vardenafil and avanafil are also PDE5 inhibitors, but they are separate active ingredients. Sharing a primary molecular target does not make their pharmacokinetics, food effects, selectivity profiles or labeled uses identical.
For a structured view of those class-level similarities and differences, see sildenafil vs other PDE5 inhibitors.
| Active Drug | Drug Class | Same Molecule as Sildenafil? |
|---|---|---|
| Sildenafil | PDE5 inhibitor | Yes |
| Tadalafil | PDE5 inhibitor | No |
| Vardenafil | PDE5 inhibitor | No |
| Avanafil | PDE5 inhibitor | No |
Sildenafil appears in more than one approved clinical-use context. In current U.S. labeling, sildenafil products are used in erectile dysfunction and pulmonary arterial hypertension, but those indications belong to specific finished products rather than to every sildenafil product automatically.
This product-specific distinction matters because an ED sildenafil tablet and a PAH sildenafil product can contain the same active drug while having different strengths, formulations, patient populations and administration frameworks. The active ingredient explains the shared pharmacology; the product label defines the approved use.
The complete indication map is covered on sildenafil uses.
| Major U.S. Use Context | Example Product Context | General Purpose |
|---|---|---|
| Erectile dysfunction | Viagra and generic ED sildenafil products | Treatment of erectile dysfunction |
| Pulmonary arterial hypertension | Revatio and corresponding sildenafil products | Treatment of PAH within the applicable label |
Erectile dysfunction is the clinical context most commonly associated with the name sildenafil. Current U.S. sildenafil ED tablet labeling identifies sildenafil as a PDE5 inhibitor indicated for the treatment of erectile dysfunction.
In this setting, sildenafil does not directly produce the entire erectile response. Sexual stimulation initiates nitric-oxide signaling, which increases cGMP; sildenafil inhibits PDE5-mediated cGMP breakdown and thereby supports the physiological signaling process.
The clinical-use page sildenafil for erectile dysfunction covers the indication itself, while how sildenafil works explains the mechanism in greater depth.
| ED Concept | High-Level Meaning |
|---|---|
| Active drug | Sildenafil |
| Drug class | PDE5 inhibitor |
| Physiological pathway | NO-cGMP signaling |
| Sexual stimulation | Remains part of the physiological response framework |
Sildenafil also has an established pulmonary arterial hypertension product context. Current U.S. Revatio labeling identifies sildenafil as a PDE5 inhibitor for PAH, specifically WHO Group I, rather than for erectile dysfunction.
In adults, the Revatio label describes treatment intended to improve exercise ability and delay clinical worsening. Current labeling also includes pediatric patients 1 through 17 years old, with outcome language adapted for whether standardized exercise testing can be performed.
This use illustrates why sildenafil cannot be defined only as an erectile-dysfunction medicine. The same active drug can be developed into products for different clinical settings. See sildenafil for pulmonary hypertension for the indication-specific overview.
| PAH Context | High-Level Meaning |
|---|---|
| Condition | Pulmonary arterial hypertension, WHO Group I |
| Adult Revatio context | Improve exercise ability and delay clinical worsening |
| Pediatric Revatio context | Includes patients 1–17 years old in current U.S. labeling |
| Same product framework as ED sildenafil? | No |
Viagra and Revatio are two of the best-known sildenafil brand names, but they identify separate finished medicine products rather than different active drugs. Viagra is associated with the erectile-dysfunction context, while Revatio belongs to the pulmonary-arterial-hypertension context.
The distinction between brand and active drug helps explain why the same word sildenafil appears in multiple parts of prescribing information. Sildenafil identifies the pharmacologically active compound; the brand name identifies the specific commercial and regulatory product in which that compound appears.
For the full naming framework, see sildenafil brand names. The individual relationships are explained on sildenafil and Viagra and sildenafil and Revatio.
| Brand | Active Drug | Primary U.S. Label Context |
|---|---|---|
| Viagra | Sildenafil | Erectile dysfunction |
| Revatio | Sildenafil | Pulmonary arterial hypertension |
Generic sildenafil refers to approved medicine products marketed under the established drug name rather than the original proprietary brand identity. In the ED context, approved generic sildenafil products contain the same active drug as Viagra and are evaluated under applicable generic-drug requirements.
The word generic should therefore not be interpreted as meaning a different molecular form of sildenafil or a different PDE5 mechanism. Product-level characteristics such as manufacturer, tablet appearance and some inactive ingredients can vary while the active drug remains sildenafil.
Generic product identity is covered on generic sildenafil, while the more specific brand-versus-generic comparison is on sildenafil vs Viagra.
| Identity | Meaning |
|---|---|
| Sildenafil | Nonproprietary active-drug name |
| Generic sildenafil product | Approved product marketed using the nonproprietary drug identity |
| Viagra | Proprietary sildenafil product |
| Different core active molecule? | No in the corresponding generic-versus-reference-product context |
Sildenafil is not limited to one tablet product. Current U.S. medicine labeling includes oral tablets as well as product-specific oral suspension and intravenous formulations. Current labeling also includes an oral-film sildenafil product in the erectile-dysfunction context.
The dosage form matters because it changes how the product is administered and, in some cases, how sildenafil reaches systemic circulation. An oral tablet or suspension requires gastrointestinal absorption, while an intravenous formulation delivers sildenafil directly into systemic circulation.
Not every formulation is approved for every sildenafil indication. The product label therefore needs to be considered together with the dosage form rather than assuming that all sildenafil formulations can be used interchangeably. The site's main formulation framework is covered on sildenafil formulations.
| Dosage Form | Route | General Current U.S. Context |
|---|---|---|
| Tablet | Oral | Appears in ED and PAH product contexts |
| Oral suspension | Oral | PAH product context |
| Injection | Intravenous | Revatio PAH product context |
| Oral film | Oral | Current ED product context |
At the molecular level, sildenafil selectively inhibits PDE5, an enzyme responsible for breaking down cGMP. When PDE5 activity is inhibited, cGMP can persist longer within biological pathways in which it has already been generated.
Sildenafil does not directly manufacture nitric oxide or independently generate cGMP. Instead, it modifies the balance between cGMP production and degradation. The physiological consequence depends on the tissue and clinical context in which the NO-cGMP pathway is operating.
That high-level mechanism is enough to define the drug on this overview page. The full plain-language explanation belongs on how sildenafil works, while the technical target and pathway pages are sildenafil PDE5 inhibition and the NO-cGMP pathway.
| Mechanism Component | Role |
|---|---|
| PDE5 | Enzyme involved in cGMP breakdown |
| Sildenafil | Inhibits PDE5 |
| cGMP | Second messenger whose breakdown is reduced by PDE5 inhibition |
| Nitric oxide | Part of the upstream signaling pathway rather than something sildenafil directly creates |
After oral administration, sildenafil is absorbed into systemic circulation, distributed through the body, metabolized and ultimately eliminated. These processes are collectively described as pharmacokinetics, or PK.
Researchers characterize sildenafil exposure with measurements such as bioavailability, Tmax, Cmax and AUC, while clearance and half-life help describe how concentrations decline. Food, metabolic interactions, organ function and other variables can change parts of this concentration-time profile.
Those technical parameters are intentionally not expanded here because they form their own research silo. See sildenafil pharmacokinetics for the master PK overview.
| PK Stage | What It Describes |
|---|---|
| Absorption | Entry of sildenafil into systemic circulation |
| Distribution | Movement of the drug between blood and tissues |
| Metabolism | Enzymatic transformation of sildenafil |
| Elimination | Removal of parent drug and metabolites |
Sildenafil medicine products are supplied under prescription-drug labeling in the United States. This applies independently of whether the finished medicine is a branded product or an approved generic product.
Prescription status is an access and regulatory characteristic rather than part of sildenafil's molecular identity. Other jurisdictions can use different legal frameworks, so prescription requirements should always be interpreted for the relevant product and location.
The access question is treated separately on sildenafil prescription requirements so that this page remains focused on what sildenafil is rather than how to obtain it.
| Concept | Meaning |
|---|---|
| Active-drug identity | Sildenafil |
| U.S. medicine status | Prescription drug |
| Brand vs generic | Does not by itself remove prescription requirements |
| Jurisdiction | Can affect legal access rules |
Sildenafil has a defined safety profile that includes common adverse reactions, more serious warnings, contraindications and clinically important drug interactions. These categories serve different purposes in prescribing information and should not be treated as synonyms.
For example, headache and flushing belong to the adverse-reaction context, while prolonged erection, sudden vision or hearing changes and cardiovascular considerations appear in warnings and precautions. Nitrates and guanylate cyclase stimulators such as riociguat belong to important contraindication contexts in U.S. ED labeling.
This page only establishes the safety framework. Dedicated pages cover sildenafil side effects, sildenafil warnings, sildenafil contraindications and sildenafil drug interactions.
| Safety Category | What It Covers |
|---|---|
| Side effects | Reported adverse reactions |
| Warnings and precautions | Important risks requiring particular clinical attention |
| Contraindications | Situations in which the applicable label states the product should not be used |
| Drug interactions | Effects of combining sildenafil with other medicines or substances |
Many apparent contradictions about sildenafil disappear once the layers of medicine identity are separated. Sildenafil can refer to the active drug, while sildenafil citrate describes its salt form, a brand identifies a particular finished product and a formulation describes the physical dosage form in which that product is supplied.
The product label then adds another layer by defining the approved indication, population, strength, route and prescribing information. Two products can therefore contain the same active sildenafil while differing substantially in their practical clinical context.
This framework is especially useful for understanding why Viagra and Revatio share sildenafil but are not interchangeable finished products. For terminology depth, see sildenafil terminology.
| Identity Layer | Example |
|---|---|
| Active drug | Sildenafil |
| Salt form | Sildenafil citrate |
| Drug class | PDE5 inhibitor |
| Brand product | Viagra or Revatio |
| Dosage form | Tablet, suspension, injection or oral film depending on product |
| Label context | Product-specific approved indication and prescribing information |
Sildenafil is one active pharmaceutical drug, but it is not one single brand, one fixed tablet or one indication. Viagra is not another active ingredient separate from sildenafil, and Revatio is not a different PDE5 inhibitor simply because it has a different brand name.
Sildenafil is also not synonymous with erectile-dysfunction treatment alone. Its current medicine-product landscape includes pulmonary arterial hypertension, different dosage forms and product-specific populations in addition to ED products.
The most accurate way to interpret any statement about sildenafil is therefore to ask which level is being discussed: the active drug, a particular brand, a dosage form or a specific approved label.
| Statement | Correct? |
|---|---|
| Sildenafil is an active pharmaceutical drug | Yes |
| Sildenafil is simply another name for the Viagra brand | No |
| Every sildenafil product has the same indication | No |
| Every sildenafil product has the same dosage form | No |
| Different sildenafil brands can share the same core active-drug mechanism | Yes |
The simplest complete model has several layers. Sildenafil is the active drug; PDE5 inhibition describes its pharmacological class and primary target; individual products then add a salt form, dosage form, strength, brand or generic identity and a regulatory label.
That framework explains why one molecule can appear in products as different as an ED tablet and a PAH oral suspension or injection. The molecular pharmacology can remain related while the clinical purpose, administration and prescribing information change substantially.
From this overview, the most useful next steps depend on the question being asked: sildenafil uses for indications, how sildenafil works for mechanism, sildenafil brand names for product identity and sildenafil formulations for dosage forms.
| Question | Best Next Topic |
|---|---|
| What conditions is sildenafil used for? | Sildenafil Uses |
| How does sildenafil work? | How Sildenafil Works |
| Which brands contain sildenafil? | Sildenafil Brand Names |
| What dosage forms exist? | Sildenafil Formulations |
| How does the body process sildenafil? | Sildenafil Pharmacokinetics |
Sildenafil is the nonproprietary name of a prescription active pharmaceutical drug in the PDE5 inhibitor class. It appears in multiple branded and generic medicine products.
Sildenafil is a phosphodiesterase type 5, or PDE5, inhibitor. PDE5 inhibition reduces the breakdown of cGMP within relevant physiological signaling pathways.
Sildenafil refers to the active drug moiety, while sildenafil citrate is the citrate salt form used in many pharmaceutical products. They are related pharmaceutical terms rather than two different PDE5-inhibitor drugs.
Current U.S. sildenafil products include approved contexts for erectile dysfunction and pulmonary arterial hypertension. The applicable use depends on the particular product and its labeling.
Sildenafil is the nonproprietary active-drug name, while Viagra is a specific branded sildenafil citrate product used in the erectile-dysfunction context.
Yes. Revatio is a branded sildenafil product family used in the pulmonary-arterial-hypertension context. It contains the same active drug but has a different product and label framework from Viagra.
Current U.S. sildenafil products include oral tablets, oral suspension, intravenous injection and an oral-film product in specific clinical and brand contexts. Not every dosage form is approved for every indication.
Sildenafil inhibits PDE5, reducing PDE5-mediated breakdown of cGMP. It modifies an existing signaling pathway rather than directly creating nitric oxide or cGMP.
Sildenafil medicine products are prescription drugs in the United States. Prescription rules can differ by jurisdiction and product.
No. Sildenafil also appears in products approved for pulmonary arterial hypertension, including current Revatio labeling for adults and pediatric patients 1 through 17 years old.
No. An approved generic sildenafil counterpart uses sildenafil as the active drug. Brand and generic products can differ in product-level characteristics while sharing the relevant active ingredient.
Sildenafil safety information includes adverse reactions, warnings and precautions, contraindications and drug interactions. These categories describe different aspects of the medicine's safety profile.