Sildenafil: study card

Sildenafil — PDE5 inhibitor. Study the mechanism, listed uses and warnings from the US label on one sourced card.

Generic name: Sildenafil
Class: PDE5 inhibitor
Mechanism: During sexual stimulation, PDE5 inhibition enhances nitric oxide effects by reducing cGMP breakdown in the corpus cavernosum, supporting smooth-muscle relaxation and blood inflow. Recommended doses have no effect in the absence of sexual stimulation.
Used for: Erectile dysfunction
Common side effects: Headache; Flushing; Dyspepsia; Abnormal vision; Nasal congestion
Warnings: Nitrates or guanylate-cyclase stimulators such as riociguat are contraindicated; Prolonged erection or priapism: seek emergency medical help for an erection lasting more than 4 hours; Stop use and seek medical care for sudden vision loss or sudden decrease/loss of hearing
Interactions: Nitrates; Alpha-blockers / antihypertensives; CYP3A4 inhibitors (ritonavir)

Brand questions use only name pairings verified against the linked product source. Unverified pairings are withheld from these questions; the other study content remains available.

Read the source label ↗

Label date: 20260831 · For learning, not clinical decisions. US label and brand information; always consult the current source.

Source snapshot checked: 2026-10-21. The source document and selected fields were compared. The complete card has not had an independent clinical review.

Practice

Pronunciation

Sildenafil: sil-DEN-a-fil

Pronunciation is shown for the US English generic name.

Body system

Genitourinary · 11 Drug cards

Compare with related cards

Tadalafil

Same body system: Genitourinary

Mechanism: Inhibits PDE5, raising cGMP in corpus cavernosum smooth muscle; needs sexual stimulation to release nitric oxide.

On both cards: Used for — Erectile dysfunction · Common side effects — Headache; Flushing; Dyspepsia · Interactions — Nitrates; Alpha-blockers / antihypertensives

Only on the Tadalafil card: Used for — Benign prostatic hyperplasia (signs/symptoms); ED with BPH · Common side effects — Back pain; Myalgia · Warnings — Contraindicated with organic nitrates; Hypotension with alpha-blockers or alcohol; Priapism; sudden vision loss · Interactions — CYP3A4 inhibitors (e.g., ketoconazole, ritonavir)

An item counts as shared only when both cards use the same wording. If a card does not list an item, that is not a statement that the effect never occurs.