Is sildenafil (generic Viagra) as effective as brand-name Viagra?

Yes. Generic sildenafil contains the same active ingredient at the same strength and is bioequivalent. The 95% price drop after generic introduction in 2017-2018 made effective ED treatment widely affordable.

Can I take a PDE5 inhibitor with alcohol?

Light to moderate alcohol consumption is generally compatible. Heavy drinking can impair erection independently and may worsen PDE5i side effects like headache and flushing. Both alcohol and PDE5i lower blood pressure, so the combination warrants caution in patients with cardiovascular risk.

Is daily tadalafil (Cialis) better than on-demand?

Daily 2.5-5 mg tadalafil removes the timing question — readiness is continuous rather than dose-event coupled. Trade-offs: higher monthly cost, modestly more side-effect exposure. Patients with frequent sexual activity or who find timing pressure itself contributes to ED often prefer daily; infrequent users typically prefer on-demand.

What happens if I have a PDE5 inhibitor with nitrates?

Severe, potentially life-threatening hypotension. Nitrates (nitroglycerin, isosorbide) are an absolute contraindication. Patients on nitrates for angina cannot use PDE5i; alternative ED treatments (vacuum, injection) are used instead.

PDE5 inhibitors

Target: Phosphodiesterase type 5

Reviewed by the glpzoom Editorial Team against primary clinical sources — FDA labeling, peer-reviewed trials, and specialty-society guidelines.

Content current as of June 2026; updated when guidance or availability changes.

Last verified June 1, 2026by glpzoom Editorial Team against primary sources

~0%: of users respond to first-line PDE5i
0-60 min: typical onset
0-36 h: duration range (sildenafil → tadalafil)
~0%: cash price drop after generics (2017-2018)

What are pde5 inhibitors?

Phosphodiesterase type 5 (PDE5) inhibitors are the first-line oral treatment for erectile dysfunction. They work by blocking PDE5 from breaking down cyclic GMP, the secondary messenger that drives smooth-muscle relaxation in the corpus cavernosum.

How do pde5 inhibitors work?

Sexual stimulation triggers nitric oxide release in penile tissue, which generates cGMP. PDE5 inhibitors prevent its breakdown, allowing sustained vasodilation and erection. The class requires sexual arousal to function — these drugs are not aphrodisiacs and don't act on libido.

History of pde5 inhibitors

Sildenafil (Viagra, 1998) was the first oral ED drug and remains the prototypical PDE5 inhibitor. Tadalafil (Cialis, 2003) introduced a long half-life (~17.5 hours, marketed as 'weekend pill'). Vardenafil and avanafil followed. Generic sildenafil and tadalafil arrived 2017-2018 and dropped cash prices 95%.

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Sources

Primary sources cited above. FDA labeling, peer-reviewed trials, and specialty-society guidelines only.

Erectile Dysfunction: AUA Guideline · American Urological Association, 2018
Tadalafil for treatment of erectile dysfunction (long-term efficacy + safety) · Journal of Sexual Medicine, 2008 · PMID 18761596