Sildenafil / Viagra

ID: sildenafil

Aliases: Viagra, sildenafil, sildenafil citrate, Revatio, PDE5 inhibitor

Type: compound

Route/form: oral prescription tablet in Viagra ED context; pulmonary-hypertension products have separate dosing/route context

Status: approved

Evidence level: approved / labelled

Best data tier: approved label + human controlled/review

Support scope: human

Source types: human_physiology, label, meta_analysis, systematic_review

Linked sources: 7

Broad outcomes: Cardiovascular / lipids / blood pressure, Hormones / fertility / sexual health, Muscle growth / performance / recovery

Reading note: These are curation notes anchored to linked sources, not a clinical recommendation or protocol.

Targets / mechanism

• PDE5 inhibition
• NO/cGMP signaling preservation
• corpus cavernosum smooth-muscle relaxation
• pulmonary vascular tone modulation

Optimization domains

• erectile
• sexual
• vascular
• endothelial
• blood pressure
• cardiovascular
• exercise performance
• hypoxia
• pulmonary hypertension
• nitric oxide

Research basis

• Sildenafil has label-level evidence for erectile dysfunction and a deep RCT/meta-analysis base as the reference Viagra-class PDE5 inhibitor.
• The best performance-adjacent signal is environment-specific: acute hypoxia/altitude studies show plausible pulmonary-vascular and cardiac-output effects in some settings.
• Because sildenafil is shorter acting than tadalafil, it is useful as a separate entry rather than collapsing all Cialis/Viagra claims into one generic PDE5 bucket.

Limits, risks, and missing evidence

• Systematic reviews show sildenafil does not reliably improve hypoxic exercise performance, and the classic physiology study itself found no meaningful normoxia performance effect.
• The ED and pulmonary-vascular evidence does not prove gym performance, hypertrophy, recovery, or general cardiovascular longevity effects in healthy users.
• Nitrates, riociguat/GC stimulators, alpha-blockers, CYP3A4 inhibitors such as ritonavir, ocular/hearing warnings, blood-pressure effects, and cardiovascular suitability are central safety constraints.

Risk flags

• prescription only
• nitrate contraindication
• blood pressure interactions
• cyp3a4 interactions
• ocular hearing warnings
• hypoxia specific performance

Linked papers, labels, and reviews

1. VIAGRA (sildenafil citrate) tablets - Prescribing Information
   label / dailymed_viagra_label
   DailyMed label for oral sildenafil/Viagra, including ED dosing, nitrate/riociguat contraindications, CYP3A4 interaction cautions, and adverse-effect profile.
2. Oral phosphodiesterase-5 inhibitors and hormonal treatments for erectile dysfunction: a systematic review and meta-analysis
   meta_analysis / pubmed_pde5_ed_meta_2009
   Broad ED systematic review/meta-analysis covering sildenafil, tadalafil, vardenafil, and hormonal comparators.
3. Efficacy and safety of oral phosphodiesterase 5 inhibitors for erectile dysfunction: a network meta-analysis and multicriteria decision analysis
   meta_analysis / pubmed_pde5_ed_network_meta_2020
   Network meta-analysis comparing PDE5 inhibitors for ED efficacy and adverse effects; useful class-level efficacy/safety context.
4. Direct comparison of tadalafil with sildenafil for the treatment of erectile dysfunction: a systematic review and meta-analysis
   meta_analysis / pubmed_tadalafil_sildenafil_meta_2017
   Head-to-head tadalafil versus sildenafil systematic review/meta-analysis; useful for duration/tolerability preference framing without implying one is universally superior.
5. Sildenafil improves cardiac output and exercise performance during acute hypoxia, but not normoxia
   human_physiology / pubmed_sildenafil_hypoxia_performance_2006
   Healthy-human physiology study supporting the narrow altitude/hypoxia performance rationale and the lack of normoxia performance effect.
6. Sildenafil does not reliably improve exercise performance in hypoxia: a systematic review
   systematic_review / pubmed_sildenafil_hypoxia_review_2019
   Systematic review showing the hypoxia-performance signal is inconsistent; useful against gym-performance overclaiming.
7. Efficacy of Sildenafil on healthy humans in high-altitude hypoxia at rest and during exercise: A meta-analysis
   meta_analysis / pubmed_sildenafil_hypoxia_meta_2024
   Recent meta-analysis on sildenafil in healthy humans exposed to high-altitude hypoxia; supports route-specific and environment-specific performance context.