Sildenafil. The on-demand option. Works in 30 minutes. Lasts up to 6 hours.
Sildenafil is one of the most prescribed medications in the world. FDA-approved since 1998, it has over 25 years of clinical data behind it and a safety profile that makes it the benchmark for on-demand ED treatment.
Where tadalafil is the daily option (always in your system, ready whenever), sildenafil is the on-demand choice. Take it when you need it. It kicks in within 30 to 60 minutes and delivers reliable performance for up to 6 hours.
The mechanism is straightforward: sildenafil blocks PDE5, the enzyme that breaks down cGMP — the signaling molecule that allows smooth muscle in the penile arteries to relax. With cGMP preserved, blood flow responds to arousal the way it’s supposed to. The drug doesn’t create desire; it removes the mechanical barrier between desire and response.
Effective doses typically range from 25 mg to 100 mg, with 50 mg being the common starting point. Take it 30 to 60 minutes before activity — a high-fat meal can delay onset, so most men take it on a lighter stomach.
Generic since 2017, sildenafil isn’t an expensive drug anymore; what matters is getting the right dose for your physiology, with physician oversight that catches interactions like nitrates (a hard contraindication) before they become a problem.
Sildenafil
Sildenafil Protocol Pricing
One flat rate. Physician supervision, compounded medication, and ongoing support included.
Sildenafil 100mg, 6 pills. Generic Viagra.
Sildenafil 100mg, 18 pills total.
Sildenafil 100mg, 36 pills total.
Sildenafil 100mg, 72 pills total.
The numbers that go further than the bedroom.
Sildenafil has been studied extensively since 1998. The data on its broader health benefits is compelling.
Individual results vary. Cardiovascular and Alzheimer's data are from observational cohort studies; association does not confirm causation. Prescription required.
What sildenafil is prescribed for.
How does it work?
Fill in a brief health assessment form, 100% online — takes under 10 minutes.
Our board-certified physicians review your answers and determine if semaglutide is appropriate for you.
Fast, free delivery if granted a prescription — supplies included, discreet packaging, right to your door.
Safety & Considerations
Sildenafil is a prescription medication. Your Obsidian Genetics provider will review your full health history before prescribing.
⚠ Important Safety Information
Never take sildenafil with nitrates. This includes nitroglycerin, isosorbide, and recreational drugs known as "poppers" (amyl nitrite). Combining sildenafil with nitrates can cause a severe, potentially life-threatening drop in blood pressure.
Frequently asked question
What is sildenafil and how does it work?
Sildenafil is a PDE5 inhibitor that blocks an enzyme in smooth muscle cells, allowing blood vessels to relax and dilate. This increases blood flow to the penis in response to sexual stimulation, resulting in an erection. It is FDA-approved for erectile dysfunction since 1998 and also approved for pulmonary arterial hypertension. Emerging research suggests broader cardiovascular and cognitive benefits.
Is sildenafil the same as Viagra?
Sildenafil is the active ingredient in Viagra, a brand-name medication manufactured by Pfizer. Obsidian Genetics offers physician-prescribed generic sildenafil at a fraction of branded costs. The molecule is identical; what differs is formulation, delivery, and price.
How is sildenafil taken?
Sildenafil is taken as-needed, typically 30–60 minutes before sexual activity. Available doses are 50mg, the standard starting dose, and 100mg, the full therapeutic dose. Most men should avoid taking sildenafil more than once per day. Your Obsidian Genetics provider will recommend the best dose and timing based on your individual response.
How long does sildenafil last?
Sildenafil’s effects typically last 4–6 hours after taking the dose. You can remain responsive to sexual stimulation throughout this window. The onset is usually 30–60 minutes after dosing, so plan accordingly for the best results.
What if sildenafil doesn't work for me?
Your Obsidian Genetics provider will adjust your dose or try alternative strategies. If 50mg does not work, your provider may increase to 100mg. If sildenafil is not effective, your provider may recommend switching to tadalafil, also known as Cialis, or exploring combination therapy. Not all medications work the same way for every person.
Can food affect sildenafil's effectiveness?
Yes. High-fat meals can slow sildenafil’s absorption and delay its onset by 30 minutes or more. For faster response, take sildenafil on an empty stomach or after a light meal. Alcohol may also reduce effectiveness and increase side effects — use caution when combining the two.
Can I combine sildenafil with other ED medications?
Combining sildenafil with tadalafil or other PDE5 inhibitors is generally not recommended without specific provider guidance. However, sildenafil can sometimes be combined with other classes of ED medications or with PT-141, a melanocortin agonist, under provider supervision for enhanced effect. Always consult your provider before combining any medications.
Important: This content is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. Sildenafil is a prescription medication. A licensed Obsidian Genetics physician will evaluate your health history and determine whether sildenafil is appropriate for you. Prescription required. Individual results vary. Sildenafil is FDA-approved for erectile dysfunction and pulmonary arterial hypertension. References to cardiovascular, cognitive, and performance benefits reflect emerging clinical research and represent off-label areas of ongoing study. Always disclose all medications and health conditions to your physician. Do not take sildenafil if you use nitrates in any form.