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Head-to-head evidence comparison — which supplement is right for you?
Sildenafil (Viagra) vs Tadalafil: they're closely matched on evidence (3.8 vs 3/10); they're alternatives for libido & male vitality — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Sildenafil (Viagra) and Tadalafil are closely matched across evidence, studies, and safety.
Verdict
Mostly mechanism / observational
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
Shared outcomes (1)
Outcomes where both Sildenafil (Viagra) and Tadalafil have evidence — compare verdict strength side-by-side.
Approved on-demand ED dosing is 25-100 mg taken ~30-60 minutes before activity (50 mg typical start). PAH dosing (Revatio) is 20 mg three times daily. Any off-label use is clinician-directed; this is not an approved longevity regimen.
any
Oral tablet (sildenafil citrate)
Off-label longevity/vascular use mirrors low approved dosing (e.g. tadalafil 2.5–5 mg once daily, the dose used for BPH/daily ED) under a clinician. Not an approved longevity regimen.
any
Low daily-dose oral tablet
Acute (~30-60 min onset)
Weeks
Years
Years
Years
Years
Acute to weeks
With interacting drugs
Oral sildenafil in the treatment of erectile dysfunction.
The New England Journal of Medicine (1998) · Rct
Two sequential double-blind randomized trials of on-demand oral sildenafil in men with erectile dysfunction
Efficacy of PDE-5-inhibitors for erectile dysfunction. A comparative meta-analysis of fixed-dose regimen randomized controlled trials administering the International Index of Erectile Function in broad-spectrum populations.
International Journal of Impotence Research (2006) · Meta analysis
Comparative meta-analysis pooling fixed-dose RCTs of sildenafil, tadalafil, and vardenafil
Sildenafil citrate therapy for pulmonary arterial hypertension.
The New England Journal of Medicine (2005) · Rct
SUPER-1: randomized, double-blind, placebo-controlled trial in 278 patients with PAH
Phosphodiesterase type-5 inhibitor use in type 2 diabetes is associated with a reduction in all-cause mortality.
Heart (British Cardiac Society) (2016) · Observational
Observational cohort of PDE5-inhibitor use in type-2 diabetics at high cardiovascular risk
Using Big Data to Uncover Association Between Sildenafil Use and Reduced Risk of Alzheimer's Disease.
Studies in health technology and informatics (2023) · Observational
Large real-world database study linking PDE5-inhibitor use to lower Alzheimer's incidence
Cardiovascular outcomes among sildenafil users: results of the International Men's Health Study.
International journal of clinical practice (2008) · Observational
Observational analysis of cardiovascular outcomes among PDE5-inhibitor users (international registry)
Both Sildenafil (Viagra) and Tadalafil are closely matched — the best choice depends on your specific health goals.
For libido & male vitality, Sildenafil (Viagra) has a higher relevance score (55 vs 52).
No known interactions between Sildenafil (Viagra) and Tadalafil have been documented in our database. However, always consult a healthcare provider before combining supplements.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.