Understanding How Viagra Works in the Body

Viagra, containing the active ingredient sildenafil, is one of the most recognised treatments for erectile dysfunction. Understanding how this medication works in your body can help you make informed decisions about your treatment. At EverydayMeds, we offer both branded Viagra and generic sildenafil options, allowing you to choose the most suitable treatment following a clinical assessment with our UK-licensed prescribers.

  • Blocks PDE5 enzyme to improve blood flow to the penis
  • Requires sexual arousal to work effectively
  • Takes 30-60 minutes to start working
  • Effects can last 4-6 hours in your system
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Not sure which one? Here's the honest comparison.

Sildenafil
~60 min
~4 hrs
you like to plan ahead
Tadalafil (as-needed)Most prescribed
~30 min
up to 36 hrs
you want a whole weekend covered
Tadalafil Daily
always active
continuous
you never want to think about timing
Vardenafil
~15–30 min
~8 hrs
you want the fastest onset

How ED treatment works in your body.

Increases blood flow

Increases blood flow

When PDE5 is suppressed, blood is able to flow more freely through the body—including to the (you guessed it) penis.

Increase erections

Increase erections

More blood flow to the penis means harder, more satisfying erections once you're sexually stimulated.

The Science Behind Viagra's Mechanism of Action

What Happens When You Take Viagra

When you take Viagra (sildenafil), the medication works by targeting a specific enzyme in your body called phosphodiesterase type 5 (PDE5). This enzyme is naturally present in the blood vessels of the penis and plays a crucial role in regulating blood flow. Under normal circumstances, when you become sexually aroused, your body releases nitric oxide, which triggers a cascade of reactions leading to increased blood flow to the penis.

The PDE5 Inhibition Process

Viagra belongs to a class of medications called PDE5 inhibitors. By blocking the PDE5 enzyme, sildenafil prevents the breakdown of a chemical messenger called cyclic guanosine monophosphate (cGMP). This chemical is responsible for relaxing the smooth muscles in the blood vessels of the penis, allowing them to widen and increase blood flow. The result is improved ability to achieve and maintain an erection when sexually stimulated.

Timing and Duration of Effects

After taking Viagra, you can typically expect the medication to start working within 30 to 60 minutes. However, the timing can vary depending on several factors, including whether you've eaten recently, particularly fatty foods, which may delay absorption. The effects of sildenafil can remain in your system for approximately 4 to 6 hours, though this doesn't mean you'll have an erection for this entire duration.

The Importance of Sexual Stimulation

It's crucial to understand that Viagra doesn't automatically cause an erection. Sexual arousal and stimulation are still necessary for the medication to be effective. The medication simply enhances your body's natural response to sexual stimulation by improving blood flow to the penis. Without arousal, the initial trigger of nitric oxide release won't occur, and the medication won't produce the desired effect.

Dosage and Effectiveness

Viagra is available in three strengths: 25mg, 50mg, and 100mg tablets. Most men start with a 50mg dose, which can be adjusted up to 100mg or down to 25mg based on effectiveness and any side effects experienced. At EverydayMeds, we provide both branded Viagra and generic sildenafil in these dosages, with the generic option offering the same active ingredient at a more affordable price point. Our prescribers will determine the most appropriate starting dose during your consultation.

Factors Affecting How Viagra Works

Several factors can influence how effectively Viagra works in your body. Age can play a role, as older men may require higher doses or experience slower onset times. Underlying health conditions, particularly those affecting cardiovascular health, can impact the medication's effectiveness. Additionally, psychological factors such as stress, anxiety, or relationship issues can influence the medication's success, as these can interfere with the arousal process necessary for the medication to work.

What you need to know about erectile dysfunction

It's one of the most common conditions we treat, and one of the most treatable.

What is Erectile Dysfunction?
ED means finding it hard to get or keep an erection firm enough for sex. It's not unusual to have an off night; the point at which it's worth doing something is when it's happening regularly, or when it's starting to bother you.
How will I feel when I take ED medication?
For most men, nothing feels different day to day. The medication works in the background — when you're sexually aroused, it helps blood flow where it's needed, so erections come more easily and last longer. It doesn't cause arousal on its own. Some men notice mild, short-lived effects like a headache, facial flushing or a stuffy nose, which usually pass as the dose wears off.
Why do I need a prescription for ED medication?
ED treatments are prescription-only medicines in the UK because they aren't suitable for everyone — for example, alongside certain heart conditions or medications like nitrates. That's why we ask you to complete a short online consultation first. A UK-registered prescriber reviews your answers to make sure your chosen treatment is safe and right for you before it's dispensed.
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