Sildenafil does not have one universal dosage regimen. Current U.S. labeling uses markedly different schedules for erectile dysfunction and pulmonary arterial hypertension, and formulation-specific instructions can differ even when the active ingredient is the same.
For erectile dysfunction, current sildenafil tablet labeling describes a usual labeled starting dose of 50 mg taken as needed, generally about 1 hour before sexual activity, with a permitted timing window of 30 minutes to 4 hours. The labeled dose may be decreased to 25 mg or increased to a maximum of 100 mg based on effectiveness and tolerability, with a maximum recommended frequency of once per day.
PAH labeling uses a scheduled rather than as-needed framework and includes oral tablets, oral suspension and intravenous sildenafil. This page summarizes those label-defined frameworks for reference and explains why strength, indication, formulation and individual dose selection should not be treated as interchangeable concepts.
Dosage describes how a sildenafil product is administered within a defined regimen, including the amount used at one administration, timing, frequency and any label-defined modification rules. It is broader than tablet or formulation strength alone.
This distinction is particularly important for sildenafil because products containing the same active ingredient are approved in different clinical contexts. An ED regimen may be used as needed, whereas PAH labeling uses scheduled repeated administration.
A dosage statement is therefore meaningful only when its indication and product context are clear. A number such as 20 mg, 50 mg or 100 mg cannot by itself identify the intended regimen.
| Term | Meaning |
|---|---|
| Strength | Amount of sildenafil contained in one tablet, film, measured suspension volume or other dosage form. |
| Dose | Amount administered at one time within a defined regimen. |
| Frequency | How often administration occurs under the applicable label. |
| Dosage regimen | Combined amount, timing and frequency framework. |
Approved prescribing information connects sildenafil dosage to a specific indication, dosage form and product. This prevents dosing information for one sildenafil context from being transferred automatically to another merely because the active ingredient name is the same.
Current U.S. ED tablet labeling, for example, describes an as-needed regimen with 25 mg, 50 mg and 100 mg tablet strengths. Current REVATIO labeling for PAH uses 20 mg tablets, a 10 mg/mL oral suspension and an intravenous formulation within scheduled regimens.
Product labeling can also differ because of formulation-specific administration instructions, approved populations and regulatory history. General information on this page therefore describes what labels say rather than selecting a regimen for a particular person.
| Factor | Why It Matters |
|---|---|
| Indication | ED and PAH use fundamentally different dosing frameworks. |
| Product | The applicable prescribing information defines the approved regimen. |
| Formulation | Tablet, oral film, suspension and injection have different administration contexts. |
| Population | Age, organ function and other factors can change label-defined recommendations. |
| Drug interactions | Some interacting medicines lead to specific dosage modifications in labeling. |
For most patients with erectile dysfunction, current U.S. sildenafil tablet labeling describes 50 mg taken as needed approximately 1 hour before sexual activity. The medication may be taken anywhere from 30 minutes to 4 hours before sexual activity.
Based on effectiveness and tolerability, labeling permits the dose to be decreased to 25 mg or increased to a maximum recommended dose of 100 mg. The maximum recommended dosing frequency is once per day.
These numbers describe the general approved framework, not an instruction to choose a particular dose. The appropriate starting or subsequent dose can depend on the specific product label, interacting medicines and clinical factors.
| ED Label Element | General U.S. Label Information |
|---|---|
| Usual labeled dose for most patients | 50 mg as needed |
| Typical timing | Approximately 1 hour before sexual activity |
| Permitted timing window | 30 minutes to 4 hours before sexual activity |
| Labeled lower dose | 25 mg |
| Maximum recommended dose | 100 mg |
| Maximum recommended frequency | Once per day |
Pulmonary arterial hypertension uses a fundamentally different sildenafil dosing framework from erectile dysfunction. Current REVATIO labeling recommends 20 mg orally three times a day in adults, with titration up to a maximum of 80 mg three times a day if required based on symptoms and tolerability.
REVATIO injection uses a different formulation and amount: the adult labeled dose is 10 mg by intravenous bolus three times a day. The label states that a 10 mg intravenous dose is predicted to provide a pharmacological effect of sildenafil and its N-desmethyl metabolite equivalent to a 20 mg oral dose.
Current REVATIO labeling also contains weight-based pediatric PAH regimens for patients 1 to 17 years old. Because other sildenafil PAH products can have different pediatric labeling due to product-specific regulatory circumstances, the label for the particular product remains essential.
| PAH Label Context | Current REVATIO Framework |
|---|---|
| Adults, oral | 20 mg three times a day; may be titrated up to 80 mg three times a day if required based on symptoms and tolerability |
| Adults, intravenous | 10 mg intravenous bolus three times a day |
| Pediatric patients ≤20 kg | 10 mg orally three times a day |
| Pediatric patients 20 kg to 45 kg | 20 mg orally three times a day |
| Pediatric patients >45 kg | 20 mg orally three times a day; labeling allows titration up to 40 mg three times a day if required based on symptoms and tolerability |
Sildenafil is available in several current U.S. formulation contexts, and the dosage form cannot be separated from its approved use. Conventional ED products include film-coated tablets, while VYBRIQUE provides sildenafil as an oral film. PAH products include tablets and oral suspension, and REVATIO also has an intravenous formulation.
VYBRIQUE illustrates why formulation and strength should be distinguished from dosage. Its oral film is available in 25 mg, 50 mg, 75 mg and 100 mg strengths, while its general ED dosing framework remains 50 mg as needed for most patients, with labeled adjustment down to 25 mg or up to 100 mg.
For PAH, current oral suspensions are commonly labeled at 10 mg/mL, while REVATIO injection contains 10 mg/12.5 mL. Those concentration or strength statements describe the formulation and do not independently define how it should be administered.
| Formulation | Current Label Context |
|---|---|
| ED film-coated tablet | Common strengths 25 mg, 50 mg and 100 mg; as-needed ED regimen |
| VYBRIQUE oral film | 25 mg, 50 mg, 75 mg and 100 mg films; as-needed ED regimen |
| PAH tablet | 20 mg tablet within a scheduled PAH regimen |
| PAH oral suspension | 10 mg/mL formulation within a scheduled PAH regimen |
| REVATIO injection | 10 mg/12.5 mL single-dose vial for intravenous administration |
Strength describes how much sildenafil is contained in a single dosage form or unit concentration. Dosage describes how one or more of those units are used within the applicable labeled regimen.
This explains why two products can contain sildenafil yet use very different strengths. A 20 mg PAH tablet belongs to a scheduled PAH framework, while 25 mg, 50 mg and 100 mg tablets commonly belong to the ED product framework.
Strength should therefore never be used as shorthand for indication or regimen. Even the presence of a particular strength, such as the 75 mg VYBRIQUE oral film, does not mean that the strength itself defines a universal starting dose.
| Concept | Example |
|---|---|
| Strength | A tablet containing 50 mg sildenafil |
| Liquid concentration | An oral suspension containing 10 mg/mL |
| Dose | The amount administered at one scheduled or as-needed administration |
| Frequency | Once-daily maximum in the ED label versus three-times-daily scheduled PAH regimens |
Dose describes the amount administered, while exposure describes the resulting sildenafil concentrations over time. AUC characterizes integrated exposure and Cmax characterizes the observed peak concentration.
The distinction is important because the same administered dose can produce different exposure in different physiological or interaction contexts. Older age, hepatic impairment, severe renal impairment and inhibition of sildenafil metabolism are examples of factors that can raise systemic exposure without changing the nominal dose.
This is why product labels sometimes recommend a different starting regimen in populations with higher expected exposure. Pharmacokinetic data explain the rationale, but dose selection itself remains a clinical and label-based decision.
| Concept | Meaning |
|---|---|
| Dose | Amount of sildenafil administered |
| AUC | Integrated systemic exposure |
| Cmax | Peak observed plasma concentration |
| Tmax | Time of the observed concentration peak |
| Exposure modifier | A factor that changes concentrations without necessarily changing the administered amount |
Dose proportionality is a pharmacokinetic concept describing how sildenafil exposure changes across studied doses. Current ED labeling states that sildenafil pharmacokinetics are dose-proportional over the recommended dose range.
That observation means measures such as AUC and Cmax generally increase as dose increases under comparable study conditions. It does not mean that clinical response or adverse effects increase in an identical linear proportion.
Dose proportionality also does not provide an algorithm for choosing an individual dose. Detailed analysis of the relationship between administered dose and exposure remains on the dedicated research page.
| Topic | Dedicated Resource |
|---|---|
| Dose and exposure relationship | Sildenafil Dose Proportionality |
| Strength reference | Sildenafil Strengths Guide |
The meaning of a missed sildenafil dose depends first on whether the applicable regimen is scheduled or used as needed. ED sildenafil is generally labeled as an as-needed medicine rather than as a fixed daily schedule, so the conventional concept of replacing a missed scheduled dose does not map directly onto that regimen.
PAH sildenafil, by contrast, uses scheduled repeated administration. Missed-dose instructions should therefore come from the specific PAH product's current patient information or the prescribing clinician rather than being borrowed from an ED product.
A universal missed-dose instruction would be inappropriate on a general sildenafil page because formulation, indication, age group and product labeling can differ. Product-specific instructions remain the authoritative source.
| Regimen Context | Missed-Dose Interpretation |
|---|---|
| ED as-needed regimen | Not a conventional fixed scheduled-dose framework |
| PAH scheduled regimen | Product-specific missed-dose guidance is relevant |
| Pediatric PAH | Follow the specific product and prescriber instructions |
ED-oriented sildenafil labels contain several specific situations in which a lower starting dose or a modified maximum frequency is recommended or considered. These are label examples of how pharmacokinetic exposure and interaction risk can influence the dosage framework.
Current tablet labeling recommends or considers a 25 mg starting dose in several contexts, including age over 65 years, hepatic impairment, severe renal impairment with creatinine clearance below 30 mL/min, use with an alpha-blocker and use with certain strong CYP3A4 inhibitors or erythromycin. Ritonavir has a more restrictive labeled framework because it can produce a very large increase in sildenafil exposure.
These rules are product- and indication-specific. For example, REVATIO PAH labeling does not simply copy the ED renal-impairment adjustment framework; current REVATIO labeling states that no dose adjustment is required for renal impairment, including severe impairment. This is why dose-adjustment information should never be transferred automatically between ED and PAH labels.
| ED Label Context | General Label Framework |
|---|---|
| Age >65 years | Consider a 25 mg starting dose |
| Hepatic impairment | Consider a 25 mg starting dose |
| Severe renal impairment, CrCl <30 mL/min | Consider a 25 mg starting dose |
| Concomitant alpha-blocker | Patient should be stable on alpha-blocker therapy; ED labeling uses a 25 mg sildenafil starting dose |
| Strong CYP3A4 inhibitor or erythromycin | Consider a 25 mg starting dose |
| Ritonavir | ED labeling limits the recommended dose to 25 mg within a 48-hour period |
Viagra, Revatio and generic sildenafil share the sildenafil active moiety but do not represent one interchangeable dosing framework. Viagra and conventional generic ED sildenafil tablets use an as-needed erectile-dysfunction regimen, while Revatio is labeled for scheduled PAH treatment.
Current U.S. sildenafil products also extend beyond those older brand relationships. VYBRIQUE is an ED oral-film product using an as-needed sildenafil regimen, while LIQREV is a PAH oral suspension using a scheduled regimen. These examples reinforce that brand name, dosage form, strength and indication all need to be identified before interpreting dosage information.
Even products used for the same indication can have formulation-specific administration details. The active ingredient alone therefore does not tell a reader how a particular sildenafil product should be taken.
| Product Context | Dosage Framework |
|---|---|
| Viagra / conventional generic ED tablets | As-needed ED dosing; generally 25 mg to 100 mg within the labeled framework |
| VYBRIQUE oral film | As-needed ED dosing with formulation-specific administration instructions |
| Revatio | Scheduled PAH oral and intravenous regimens |
| LIQREV | Scheduled PAH oral-suspension regimen |
| Other generic sildenafil products | Interpret according to the specific approved product and reference-product context |
A label-based page can report approved dosing frameworks, but it cannot determine which regimen is appropriate for a particular person. The same sildenafil dose can produce different exposure depending on interacting medicines, age, organ function and other clinical variables.
The numerical information on this page should therefore be read as regulatory reference information. Statements such as 50 mg for most ED patients or 20 mg three times daily in an adult PAH label describe approved population-level frameworks rather than recommendations generated for an individual reader.
Actual prescribing also requires confirmation of indication, contraindications, drug interactions and the current label for the specific product being used.
| Covered | Not Covered |
|---|---|
| Current label-based regimen examples | Selection of an individual's dose |
| Differences between ED and PAH dosing | Diagnosis or indication selection |
| General label-defined adjustment contexts | Personalized interaction management |
| Formulation-specific administration context | Individual treatment planning |
Current U.S. ED tablet labeling states that for most patients the recommended dose is 50 mg taken as needed approximately 1 hour before sexual activity. It may be taken from 30 minutes to 4 hours beforehand, with labeling allowing adjustment to 25 mg or up to a maximum of 100 mg based on effectiveness and tolerability.
Current U.S. ED labeling states that the maximum recommended dosing frequency is once per day.
No. ED labeling generally uses an as-needed regimen, while current PAH labeling uses scheduled repeated dosing. For example, current REVATIO adult oral labeling recommends 20 mg three times a day, with label-defined titration possible in that PAH context.
No. Strength describes how much sildenafil is contained in a tablet, film or measured volume, while dosage describes the amount, timing and frequency used within the applicable regimen.
ED labels use lower starting-dose frameworks in certain settings associated with higher exposure or interaction risk, including older age, hepatic impairment, severe renal impairment and some interacting medicines. The exact rule depends on the specific product and indication.
No. Sildenafil products can differ by indication, dosage form, strength and approved labeling. ED tablets and oral film, PAH tablets and suspension, and intravenous sildenafil should be interpreted using their own product-specific prescribing information.