BNF Sildenafil UK: Clinical Guide | Cured Pharmacy

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BNF Sildenafil: Doctor-Reviewed Treatment Guide

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BNF Sildenafil: Doctor-Reviewed Treatment Guide

Published on: June 03, 2026

Searching for BNF sildenafil UK online pharmacy guidance? At Cured Pharmacy, our UK-registered clinical team provides evidence-based sildenafil treatment from £0.45 per tablet, with transparent pricing and free online consultations under 3 minutes. All prescriptions are issued by UK prescribers following clinical assessment.

What Is Sildenafil According to the BNF?

Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor listed in the British National Formulary (BNF) for the treatment of erectile dysfunction in adult men [1]. The medication works by relaxing blood vessels in the penis, allowing increased blood flow during sexual stimulation to help achieve and maintain an erection suitable for intercourse.

The BNF specifies that sildenafil is licensed for use approximately one hour before sexual activity, with effects lasting up to four hours in clinical studies [1]. Unlike daily treatments, sildenafil is taken on demand, making it suitable for men who prefer flexible dosing rather than continuous medication. At Cured Pharmacy, sildenafil is available from £0.45 per tablet following assessment by a UK prescriber.

As a prescription-only medicine in the UK, sildenafil requires clinical evaluation to ensure it is safe and appropriate for your individual circumstances. Our superintendent pharmacist Tarun Kumar (GPhC 2233073) oversees all dispensing to ensure you receive genuine UK-licensed medication.

BNF Sildenafil Dosage and Administration

Clinical studies demonstrate that sildenafil achieves peak plasma concentrations within 30 to 120 minutes after oral administration, with a median time of 60 minutes [2]. Taking the tablet on an empty stomach may result in faster absorption, whilst a high-fat meal can delay onset by up to one hour.

At Cured Pharmacy, our UK prescribers provide personalised dosing guidance based on your individual response and any concurrent medications that may interact with sildenafil, such as nitrates or alpha-blockers.

Standard Dosing Recommendations

The BNF recommends an initial sildenafil dose of 50mg taken approximately one hour before sexual activity [1]. Depending on efficacy and tolerability, your UK prescriber may adjust this to 25mg or increase to a maximum of 100mg per dose. The medication should not be taken more than once in a 24-hour period.

For men over 65 years or those with hepatic or renal impairment, the BNF advises starting with a lower 25mg dose to minimise potential side effects [1]. Your prescriber will review your medical history, current medications, and any underlying health conditions during your free online consultation to determine the most appropriate starting dose.

Clinical Evidence for Sildenafil Efficacy

Sildenafil has been extensively studied since its approval, with over 20 years of clinical data supporting its efficacy in treating erectile dysfunction across diverse patient populations [2]. In randomised controlled trials, approximately 70-80% of men reported improved erections compared to 25% on placebo, demonstrating significant clinical benefit.

A meta-analysis of 27 double-blind, placebo-controlled trials involving over 6,000 participants found that sildenafil significantly improved erectile function scores across all doses (25mg, 50mg, and 100mg) [3]. Men with diabetes, cardiovascular disease, and post-prostatectomy erectile dysfunction also showed meaningful improvements, though response rates were slightly lower in these subgroups.

The International Index of Erectile Function (IIEF) questionnaire, used in most clinical trials, consistently shows sildenafil improves not only erectile function but also orgasmic function, sexual desire, intercourse satisfaction, and overall sexual satisfaction [3]. These improvements are maintained with long-term use, as demonstrated in open-label extension studies lasting up to four years.

Treatment Active Ingredient Duration Starting Price
Sildenafil Sildenafil citrate Up to 4 hours From £0.45
Tadalafil Tadalafil Up to 36 hours From £9.99
Viagra Connect Sildenafil citrate Up to 4 hours From £11.49
Cialis Tadalafil Up to 36 hours From £53.00

Sildenafil vs Tadalafil: BNF Comparison

Both medications are PDE5 inhibitors with similar efficacy rates in clinical trials, though individual response varies [4]. Tadalafil is also available as a low-dose daily option (2.5mg or 5mg), which maintains constant drug levels and allows for sexual activity at any time without planning. At Cured Pharmacy, tadalafil is available from £0.45 following prescriber assessment.

Your UK prescriber will discuss your lifestyle, frequency of sexual activity, and any preference for on-demand versus daily dosing to recommend the most suitable treatment. Both sildenafil and tadalafil are available through our online consultation service, with same-day dispatch for orders placed before 3pm on weekdays.

Duration of Action

The primary difference between sildenafil and tadalafil lies in their duration of action. Sildenafil remains effective for approximately four hours, making it suitable for planned sexual activity [1]. Tadalafil, by contrast, has a half-life of 17.5 hours and can remain effective for up to 36 hours, earning it the nickname 'the weekend pill' [4].

For men who prefer spontaneity or engage in sexual activity more than once per weekend, tadalafil may offer greater flexibility. However, sildenafil's shorter duration means it clears the body faster, which some men prefer if they experience side effects or take other medications.

Common Side Effects and Safety Considerations

Sildenafil is contraindicated in men taking nitrates for angina or chest pain, as the combination can cause a dangerous drop in blood pressure [1]. It should also be used with caution in men taking alpha-blockers for prostate problems or hypertension. During your online consultation, our UK prescribers will review your full medication list to identify any potential interactions.

At Cured Pharmacy, we only dispense genuine UK-licensed sildenafil from reputable manufacturers. Counterfeit erectile dysfunction medications purchased from unregulated sources may contain incorrect doses, contaminants, or no active ingredient at all, posing serious health risks.

Frequently Reported Side Effects

The BNF lists the most common side effects of sildenafil as headache, facial flushing, dyspepsia, and nasal congestion, which occur in approximately 10-16% of users [1]. These effects are generally mild to moderate and resolve within a few hours as the medication is metabolised. Visual disturbances, including a blue tinge to vision or increased light sensitivity, occur in about 3% of men taking the 100mg dose.

Serious side effects are rare but include priapism (a prolonged erection lasting more than four hours), sudden vision loss, and sudden hearing loss [1]. If you experience any of these symptoms, you should seek immediate medical attention. Men with a history of cardiovascular disease should be assessed carefully, as sexual activity itself carries cardiac risk.

How to Access BNF Sildenafil UK Online Pharmacy

Cured Pharmacy offers transparent upfront pricing with no hidden consultation fees. Sildenafil starts from £0.45 per tablet, with the exact cost depending on the strength and quantity prescribed. You'll see the full price before completing your consultation, ensuring complete transparency.

Our service is designed for convenience without compromising clinical safety. All prescribers are registered with the General Medical Council (GMC) and follow MHRA guidelines for remote prescribing. If sildenafil is not suitable for you, your prescriber may recommend an alternative treatment such as tadalafil or suggest you consult your GP for further investigation of underlying causes.

Free Online Consultation Process

Accessing sildenafil through Cured Pharmacy begins with a free online consultation that takes under three minutes to complete. You'll answer questions about your medical history, current medications, cardiovascular health, and the nature of your erectile dysfunction. A UK-registered prescriber reviews your responses to determine whether sildenafil is safe and appropriate for you.

If approved, your prescription is sent electronically to our UK-registered pharmacy (GPhC 9012511), where our team dispenses your medication in discreet, unmarked packaging. Orders placed before 3pm on weekdays are dispatched the same day via Royal Mail, with next-day delivery available for an additional fee.

Scientific References

  1. Joint Formulary Committee. (2024). British National Formulary (BNF) 87. BMJ Group and Pharmaceutical Press. https://bnf.nice.org.uk/ [accessed 13 August 2026]
  2. Goldstein, I., Lue, T. F., Padma-Nathan, H., Rosen, R. C., Steers, W. D., & Wicker, P. A. (1998). Oral sildenafil in the treatment of erectile dysfunction. New England Journal of Medicine, 338(20), 1397–1404. https://doi.org/10.1056/NEJM199805143382001 [accessed 13 August 2026]
  3. Fink, H. A., Mac Donald, R., Rutks, I. R., Nelson, D. B., & Wilt, T. J. (2002). Sildenafil for male erectile dysfunction: a systematic review and meta-analysis. Archives of Internal Medicine, 162(12), 1349–1360. https://doi.org/10.1001/archinte.162.12.1349 [accessed 13 August 2026]
  4. Carson, C. C., & Lue, T. F. (2005). Phosphodiesterase type 5 inhibitors for erectile dysfunction. BJU International, 96(3), 257–280. https://doi.org/10.1111/j.1464-410X.2005.05614.x [accessed 13 August 2026]
  5. NHS. (2026). Erectile dysfunction (impotence). https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ Accessed 13 August 2026.

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.

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Faq

What is the BNF sildenafil UK online pharmacy recommended dose?
The BNF recommends starting with 50mg sildenafil approximately one hour before sexual activity, which may be adjusted to 25mg or 100mg based on efficacy and tolerability. Your UK prescriber will determine the most appropriate dose during your consultation.
How long does sildenafil take to work?
Sildenafil typically takes 30 to 60 minutes to become effective, with peak plasma concentrations reached within one hour. Taking it on an empty stomach may speed absorption, whilst a high-fat meal can delay onset.
Can I take sildenafil every day?
Sildenafil is designed for on-demand use and should not be taken more than once in 24 hours. If you require daily treatment, your prescriber may recommend low-dose daily tadalafil as an alternative.
Is sildenafil available without prescription in the UK?
No, sildenafil is a prescription-only medicine in the UK and requires assessment by a registered prescriber. At Cured Pharmacy, you complete a free online consultation which is reviewed by a UK prescriber before any medication is dispensed.
What is the difference between sildenafil and Viagra?
Sildenafil is the active ingredient in Viagra, the original branded product. Generic sildenafil contains the same active ingredient and works identically but costs significantly less—from £0.45 per tablet at Cured Pharmacy compared to branded alternatives.
Can I drink alcohol with sildenafil?
Small amounts of alcohol are unlikely to affect sildenafil, but excessive drinking can impair erectile function and increase the risk of side effects such as dizziness or low blood pressure. Moderation is advised.
How much does BNF sildenafil cost at UK online pharmacy?
At Cured Pharmacy, sildenafil starts from £0.45 per tablet with transparent upfront pricing. The final cost depends on the strength and quantity prescribed by your UK prescriber following clinical assessment.
What should I do if sildenafil doesn't work?
If sildenafil is ineffective after several attempts, contact your prescriber to discuss dose adjustment or alternative treatments such as tadalafil. Underlying causes like low testosterone, diabetes, or psychological factors may require further investigation by your GP.
Tarun Kumar, Prescribing Pharmacist

Medically reviewed by

Tarun Kumar, Prescribing Pharmacist (GPhC 2233073)

Reviewed on: June 03, 2026

Last reviewed: 13 August 2026

Last updated on 13 August 2026.

Review History

Our experts continually monitor new findings in health and medicine, and we update our articles when new information becomes available.

Why this page was updated on 13 August 2026

Content checked and updated as part of our periodic review, to ensure accuracy and currentness.

Current version (13 August 2026)

Edited by: The Editorial Team

Medically reviewed by:

Tarun Kumar, GPhC No. 2233073, Prescribing Pharmacist


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