How Does Viagra Work: UK Prescription Guide | Cured

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How Does Viagra Work: UK Prescription Requirements

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Sildenafil - UK-licensed prescription Treatment
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Sildenafil

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Tadalafil - UK-licensed prescription Treatment
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Tadalafil

From £9.99

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Sildenafil Eropid - UK-licensed prescription Treatment
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Sildenafil Eropid

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Tadalafil (Teva) - UK-licensed prescription Treatment
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Tadalafil (Teva)

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Avarante Tablets Tadalafil Tablets 10mg - UK-licensed prescription Treatment
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Avarante Tablets Tadalafil Tablets 10mg

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Viagra Connect 50mg - UK-licensed prescription Treatment
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How Does Viagra Work: UK Prescription Requirements

Understanding how does viagra work uk prescription requirements is essential before starting treatment for erectile dysfunction. Viagra (sildenafil citrate) is a PDE5 inhibitor that enhances blood flow to the penis during sexual stimulation, and in the UK, it requires a clinical assessment by a registered prescriber before dispensing. At Cured Pharmacy, you'll access genuine UK-licensed sildenafil from £0.45 with a free online consultation completed in under three minutes.

How Does Viagra Work: The Science Behind Sildenafil

Viagra contains sildenafil citrate, which belongs to a class of medications called phosphodiesterase type 5 (PDE5) inhibitors [1]. During sexual arousal, the body releases nitric oxide in the erectile tissue of the penis, which activates an enzyme that produces cyclic guanosine monophosphate (cGMP). This chemical messenger relaxes smooth muscle cells in the blood vessels, allowing increased blood flow to create an erection.

The enzyme PDE5 naturally breaks down cGMP, which can limit erectile function in men with ED. Sildenafil works by selectively inhibiting PDE5, preventing the breakdown of cGMP and maintaining higher concentrations in the erectile tissue [1]. This allows the smooth muscle to remain relaxed for longer periods, facilitating improved blood flow and stronger erections when sexually stimulated.

It's crucial to understand that Viagra does not cause automatic erections — sexual stimulation is still required to trigger the initial nitric oxide release. Clinical trials demonstrate that sildenafil significantly improves erectile function scores, with approximately 70-80% of men experiencing improved erections across various ED severities [2].

UK Prescription Requirements for Viagra and Sildenafil

In the UK, Viagra 25mg, 50mg, and 100mg tablets are prescription-only medicines (POM) regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). This means you must receive a valid prescription from a UK-registered prescriber before a pharmacy can legally dispense the medication. Viagra Connect 50mg is available over the counter, but higher doses require prescription authorisation.

UK prescribers assess several factors before issuing a sildenafil prescription: your medical history, current medications, cardiovascular health, and any contraindications such as recent stroke, severe heart failure, or use of nitrate medications for angina [3]. Men taking nitrates must not use sildenafil, as the combination can cause dangerous drops in blood pressure.

At Cured Pharmacy, our UK-registered clinical team conducts a comprehensive online assessment that typically takes under three minutes to complete. You'll answer questions about your health history, current medications, and ED symptoms. A qualified prescriber reviews your responses and, if clinically appropriate, issues a prescription for the most suitable dose and formulation.

Online Prescription Process at Cured Pharmacy

Our streamlined online consultation ensures you receive safe, appropriate treatment without the need for face-to-face appointments. After completing your medical questionnaire, our prescribers typically review and approve suitable applications within hours. If your assessment raises any concerns, our clinical team may request additional information or recommend an in-person GP consultation to ensure your safety.

How Long Does Viagra Take to Work and How Long Does It Last?

Sildenafil is rapidly absorbed after oral administration, with peak plasma concentrations reached approximately 60 minutes after taking the tablet on an empty stomach [4]. Most men notice effects within 30-60 minutes, though this can vary based on individual metabolism, food intake, and alcohol consumption. Taking Viagra with a high-fat meal can delay absorption by up to one hour.

The effects of sildenafil typically last for 4-6 hours, during which time you may find it easier to achieve and maintain erections with sexual stimulation [4]. This doesn't mean you'll have an erection for four hours continuously — rather, the medication remains active in your system, allowing you to respond to sexual arousal during this window.

The half-life of sildenafil is approximately 3-5 hours, meaning half the dose is eliminated from your body during this period. Factors such as age, liver function, and kidney function can affect how long the medication remains active. Older men and those with hepatic or renal impairment may experience longer duration of effects and may require dose adjustments.

Optimising Viagra Effectiveness

For best results, take sildenafil on an empty stomach or after a light meal, approximately one hour before anticipated sexual activity. Avoid excessive alcohol consumption, as this can impair erectile function and reduce the medication's effectiveness. If you don't achieve satisfactory results on your first attempt, try the medication on at least 4-6 separate occasions before concluding it's ineffective, as response can improve with repeated use [2].

Treatment Active Ingredient Duration of Action Starting Price
Sildenafil Sildenafil citrate 4-6 hours From £0.45
Sildenafil Eropid Sildenafil citrate 4-6 hours From £8.99
Viagra Connect 50mg Sildenafil citrate 4-6 hours From £11.49
Tadalafil Tadalafil Up to 36 hours From £9.99
Tadalafil (Teva) Tadalafil Up to 36 hours From £9.99
Cialis (Tadalafil) Tadalafil Up to 36 hours From £53.00

Sildenafil vs Viagra: Understanding Generic and Branded Options

Viagra is the original branded version of sildenafil citrate, manufactured by Pfizer. Since the patent expired in 2013, numerous pharmaceutical companies have produced generic sildenafil containing the identical active ingredient at the same doses. Generic sildenafil is bioequivalent to Viagra, meaning it works in exactly the same way with identical efficacy and safety profiles.

The primary difference between branded Viagra and generic sildenafil is cost. At Cured Pharmacy, generic sildenafil starts from £0.45 per tablet, offering significant savings compared to branded alternatives. All our sildenafil products are UK-licensed, MHRA-approved medications manufactured to the same stringent quality standards as branded Viagra.

Some men prefer branded Viagra due to familiarity or perceived quality, while others opt for generic sildenafil to reduce costs without compromising effectiveness. Our range includes both options: generic Sildenafil and Sildenafil Eropid, as well as branded Viagra Connect 50mg for those who prefer the original formulation.

Common Side Effects and Safety Considerations

Sildenafil is generally well-tolerated, but like all medications, it can cause side effects in some men. The most commonly reported side effects include headache (affecting approximately 16% of users), facial flushing (10%), dyspepsia or indigestion (7%), and nasal congestion (4%) [1][3]. These effects are usually mild to moderate and diminish with continued use.

Visual disturbances, including a blue tinge to vision or increased light sensitivity, occur in approximately 3% of men taking sildenafil [3]. This happens because PDE5 is also present in the retina, and sildenafil can have minor effects on colour perception. These visual changes are temporary and resolve once the medication is eliminated from the body.

Serious side effects are rare but require immediate medical attention. Priapism — a painful erection lasting more than four hours — occurs in less than 1% of users but constitutes a medical emergency requiring prompt treatment to prevent permanent damage [3]. Sudden vision loss or hearing loss, while extremely rare, should prompt immediate discontinuation and medical consultation.

Men with cardiovascular conditions should exercise particular caution. Sildenafil can cause small, temporary decreases in blood pressure, which is usually not problematic for healthy men but may pose risks for those with unstable angina, recent heart attack or stroke, or severe heart failure. Your prescriber will assess your cardiovascular risk before approving treatment.

Drug Interactions to Avoid

Never combine sildenafil with nitrate medications (such as glyceryl trinitrate for angina) or recreational drugs containing nitrites ('poppers'), as this combination can cause life-threatening drops in blood pressure [3]. Alpha-blockers used for prostate problems or hypertension can also interact with sildenafil, requiring dose adjustments or careful timing of administration. Always disclose all medications and supplements during your consultation.

Alternative Erectile Dysfunction Treatments Available at Cured Pharmacy

While sildenafil is the most widely prescribed ED treatment in the UK, it's not suitable for everyone. Tadalafil (the active ingredient in Cialis) offers a longer duration of action, remaining effective for up to 36 hours compared to sildenafil's 4-6 hours [5]. This extended window allows for more spontaneity, as you don't need to time the medication as precisely before sexual activity.

Tadalafil is also available as a low-dose daily tablet (2.5mg or 5mg), which maintains constant medication levels in your system, allowing you to be ready for sexual activity at any time without planning ahead. This option suits men who prefer not to take medication on demand or who engage in sexual activity more than twice weekly.

At Cured Pharmacy, we offer both sildenafil and tadalafil in multiple formulations, including generic versions and branded options. Our prescribers will discuss which medication best suits your lifestyle, preferences, and medical history during your online consultation. Both medications are highly effective, with choice often coming down to personal preference regarding duration of action and dosing schedule.

Scientific References

  1. Corbin, J. D., & Francis, S. H. (1999). Cyclic GMP phosphodiesterase-5: target of sildenafil. Journal of Biological Chemistry, 274(20), 13729–13732. https://doi.org/10.1074/jbc.274.20.13729
  2. Goldstein, I., et al. (1998). Oral sildenafil in the treatment of erectile dysfunction. New England Journal of Medicine, 338(20), 1397–1404. https://doi.org/10.1056/NEJM199805143382001
  3. Medicines and Healthcare products Regulatory Agency. (2021). Sildenafil 25mg, 50mg and 100mg film-coated tablets: Summary of Product Characteristics. GOV.UK. https://products.mhra.gov.uk/
  4. Nichols, D. J., et al. (2002). Pharmacokinetics of sildenafil after single oral doses in healthy male subjects: absolute bioavailability, food effects and dose proportionality. British Journal of Clinical Pharmacology, 53(Suppl 1), 5S–12S. https://doi.org/10.1046/j.0306-5251.2001.00027.x
  5. Carson, C. C., et al. (2004). The efficacy and safety of tadalafil: an update. BJU International, 93(9), 1276–1281. https://doi.org/10.1111/j.1464-410X.2004.04808.x

Information on this page is for educational purposes only and is not medical advice. All prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting any new medication. Erectile dysfunction can be a symptom of underlying health conditions, and appropriate medical evaluation is recommended.

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Faq

How does Viagra work in the body?
Viagra works by inhibiting the PDE5 enzyme, which breaks down cGMP in erectile tissue. This allows blood vessels in the penis to remain dilated for longer during sexual stimulation, facilitating improved blood flow and stronger erections.
Do I need a prescription for Viagra in the UK?
Yes, Viagra 25mg, 50mg, and 100mg tablets are prescription-only medicines in the UK. You must complete a clinical assessment with a UK-registered prescriber before the medication can be legally dispensed.
How long does it take for Viagra to work?
Most men notice effects within 30-60 minutes of taking sildenafil on an empty stomach. Peak concentrations occur approximately one hour after administration, though high-fat meals can delay absorption.
Can I buy Viagra online with a UK prescription?
Yes, at Cured Pharmacy you can complete a free online consultation with UK-registered prescribers who will assess your suitability and issue a prescription if clinically appropriate. Genuine UK-licensed medication is then dispensed and delivered discreetly.
What's the difference between Viagra and generic sildenafil?
Generic sildenafil contains the identical active ingredient as branded Viagra at the same doses and works in exactly the same way. The main difference is cost — generic sildenafil offers significant savings while maintaining identical efficacy and safety.
How does Viagra work if I have diabetes?
Sildenafil works through the same mechanism in men with diabetes, though effectiveness may be slightly reduced due to vascular and nerve damage associated with the condition. Clinical trials show approximately 50-60% of diabetic men respond well to sildenafil.
Can I take Viagra with alcohol?
Small amounts of alcohol are unlikely to affect Viagra's effectiveness, but excessive drinking can impair erectile function and increase the risk of side effects such as dizziness and low blood pressure. Moderation is advised.
How does the UK prescription process work at Cured Pharmacy?
Complete our online medical questionnaire (under 3 minutes), which a UK-registered prescriber reviews. If clinically suitable, a prescription is issued and your medication is dispensed from our UK pharmacy with discreet next-day delivery available.
How much does Viagra cost at Cured Pharmacy?
Viagra prices at Cured Pharmacy start from competitive rates depending on the dosage and quantity you require. Our online consultation is completely free, and we offer transparent pricing with no hidden fees, making effective erectile dysfunction treatment accessible and affordable across the UK.
Is Viagra available without a prescription in the UK?
No, Viagra is a prescription-only medication in the UK and cannot legally be purchased without one. Cured Pharmacy provides a free, confidential online consultation with our UK-registered clinicians who can issue a prescription if Viagra is suitable and safe for you.
How quickly can I get Viagra delivered in the UK?
Cured Pharmacy offers discreet next-day delivery across the UK when you order before our cut-off time. Your Viagra will arrive in plain, unmarked packaging to protect your privacy, and all orders are dispatched from our registered UK pharmacy once your prescription is approved.
What is the difference between Viagra and Sildenafil?
Viagra is the brand name while Sildenafil is the generic version containing the same active ingredient at identical dosages. Both work in exactly the same way to treat erectile dysfunction, but generic Sildenafil is typically more affordable, and Cured Pharmacy offers both options following your online consultation.
Is Viagra safe to use long term?
Viagra is generally safe for long-term use when taken as prescribed and under medical supervision. Our clinicians at Cured Pharmacy conduct thorough assessments to ensure Viagra is appropriate for your health profile and can provide ongoing prescriptions for continuous treatment of erectile dysfunction.
Tarun Kumar, Prescribing Pharmacist

Medically reviewed by

Tarun Kumar, Prescribing Pharmacist (GPhC 2233073)

Last reviewed: 17 July 2026