Sildenafil is a medication primarily known for treating erectile dysfunction (ED) and pulmonary arterial hypertension (PAH). It was originally developed by Pfizer for cardiovascular conditions, but its prominent effect on penile erection led to its approval for ED. Sildenafil is marketed under various brand names, most notably Viagra for ED and Revatio for PAH. It belongs to a class of drugs called phosphodiesterase-5 (PDE5) inhibitors (NIH MedlinePlus).
Sildenafil acts by increasing blood flow to specific tissues. For ED, this improved blood flow aids in achieving and maintaining an erection when sexual stimulation is present. For PAH, it helps to relax the blood vessels in the lungs, reducing blood pressure in the pulmonary arteries. The half-life of sildenafil is approximately 4 hours, meaning it takes about 4 hours for half of the drug to be eliminated from the body (FDA label). Individual responses to elimination can vary.
Deep dive
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Known interactions
Category rule: supplement × medication
Note
Some supplements change how the body processes medications (absorption, liver enzymes, or additive effects).
Specific pairs are checked against a licensed drug database and shown with their own severity. Always confirm with your provider or pharmacist.
Category rule: vitamin × medication
Note
Certain vitamins interact with specific medications (e.g., vitamin K with blood thinners).
Specific pairs are checked against a licensed source; confirm with your provider.
Compound-pair rule
Caution
PDE5 inhibitors add to the blood-pressure-lowering effect of antihypertensives.
Start PDE5 at the lowest effective dose and monitor for hypotension.
Compound-pair rule
Caution
PDE5 inhibitors add to the blood-pressure-lowering effect of antihypertensives.
Start PDE5 at the lowest effective dose and monitor for hypotension.
Compound-pair rule
Caution
PDE5 inhibitors add to the blood-pressure-lowering effect of antihypertensives.
Start PDE5 at the lowest effective dose and monitor for hypotension.
Compound-pair rule
Caution
PDE5 inhibitors add to the blood-pressure-lowering effect of antihypertensives.
Start PDE5 at the lowest effective dose and monitor for hypotension.
Compound-pair rule
Caution
PDE5 inhibitors add to the blood-pressure-lowering effect of antihypertensives.
Start PDE5 at the lowest effective dose and monitor for hypotension.
Compound-pair rule
Caution
PDE5 inhibitors add to the blood-pressure-lowering effect of antihypertensives.
Start PDE5 at the lowest effective dose and monitor for hypotension.
Compound-pair rule
Caution
PDE5 inhibitors lower blood pressure; amantadine can add orthostatic hypotension.
Rise slowly; monitor BP. Report dizziness or fainting.
Frequently asked
Sources referenced
* U.S. Food and Drug Administration (FDA) label
* National Institutes of Health (NIH) MedlinePlus
* European Medicines Agency (EMA) Summary of Product Characteristics (SmPC)
* PubChem
* Cochrane Library
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician.
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