How Many Sildenafil Should I Take? - Guide | Cured Pharmacy

How Many Sildenafil Should I Take?

Sildenafil

Featured Product

Sildenafil

£0.45UK-based prescribers · Discreet delivery · Free private prescription
Start Assessment →✓ Lowest price guarantee
Tarun Kumar, Prescribing Pharmacist at Cured Pharmacy

Medically reviewed by

Tarun Kumar, Prescribing Pharmacist (GPhC 2233073)

Reviewed on: 17 June 2026

Last Updated: 12 August 2026

If you have been prescribed sildenafil for erectile dysfunction and are wondering exactly how many sildenafil should I take, you are not alone. It is one of the most commonly searched questions by men who are starting treatment for the first time or who feel their current dose is not working as well as expected. Getting the dose right is genuinely important, and the answer is not always as straightforward as reading the leaflet inside the box. Factors including your age, other medicines you take, any underlying health conditions, and how your body responds to the medication all play a role in determining the correct amount for you personally.

Quick Summary

Sildenafil is available in three strengths — 25mg, 50mg, and 100mg — and the standard starting dose for most men is 50mg taken approximately one hour before sexual activity. You should never take more than one tablet in any 24-hour period, regardless of strength.

  • The recommended starting dose of sildenafil for most adult men is 50mg
  • Doses can be adjusted down to 25mg or up to a maximum of 100mg depending on response
  • You should only ever take one dose of sildenafil in a 24-hour period
  • Taking sildenafil with a large, fatty meal can significantly delay how quickly it works
  • Older adults, those on certain medications, and men with liver or kidney conditions may require a lower starting dose

Sildenafil Dose Reminder Calculator

Enter your planned time for sexual activity and your current sildenafil dose to get a personalised reminder of when to take your tablet.

Table of Contents

  1. Standard Sildenafil Doses Explained
  2. How Many Sildenafil Should I Take for My Situation
  3. Timing, Food, and Alcohol: What Affects How Well It Works
  4. Dose Adjustments for Older Adults and Special Groups
  5. What to Do If Sildenafil Is Not Working
  6. Sildenafil Safety, Side Effects, and Drug Interactions
  7. Sildenafil Dosage Comparison Table
  8. Key Takeaways
  9. When to Seek Professional Advice
  10. Scientific References
  11. Frequently Asked Questions

Standard Sildenafil Doses Explained

Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor, which means it works by relaxing the smooth muscle in the blood vessels of the penis and allowing increased blood flow in response to sexual stimulation. It is the active ingredient in the well-known branded medication Viagra, and since the patent expired it has been available as a much more affordable generic. In the UK, sildenafil is available in three licensed doses: 25mg, 50mg, and 100mg. Understanding these options is the first step in answering the question of how many sildenafil should I take.

The 50mg tablet is the standard recommended starting point for most adult men under the age of 65 who have no significant underlying health conditions and are not taking interacting medicines. It represents the middle ground between the lowest effective dose and the maximum licensed dose. The 25mg tablet is usually recommended for older men, those with mild liver or kidney impairment, or those who experience troublesome side effects on 50mg. The 100mg tablet is available for men who try 50mg and find it does not produce a sufficient response. It is always important to follow prescriber guidance rather than self-adjusting your dose.

  • 25mg: Starting dose for older adults, those on interacting medicines, or those with mild organ impairment
  • 50mg: Standard starting dose for most healthy adult men
  • 100mg: Maximum dose, used when 50mg is ineffective and well tolerated
  • Only one dose should be taken within any 24-hour window

How Many Sildenafil Should I Take for My Situation

The number of sildenafil tablets you take per episode is always one. You should never take two tablets at the same time even if you feel the first one did not work fully. If you are asking how many sildenafil should I take and wondering whether taking an extra tablet will improve the effect, the answer is no — this approach significantly increases the risk of side effects including a dangerous drop in blood pressure, severe headaches, prolonged erections, and dizziness without meaningfully improving efficacy. The correct approach is to speak to your prescriber about increasing the strength of the tablet rather than doubling up.

Most men using sildenafil 50mg find that one tablet taken on an as-needed basis is sufficient. If you try 50mg on at least four separate occasions and find it is not effective, your prescriber may consider increasing your dose to 100mg. Conversely, if 50mg works well but causes unwanted side effects, it is entirely reasonable to reduce down to 25mg. This process of dose finding is a normal part of using ED treatment and does not mean the medication is failing. It simply means you are finding the dose that best balances benefit and tolerability for your individual body.

  • Always take one tablet per episode — never two
  • Try your current dose at least four times before deciding it is ineffective
  • If side effects are troublesome on 50mg, discuss reducing to 25mg with your prescriber
  • If 50mg is ineffective after several attempts, ask about increasing to 100mg
  • Never exceed 100mg in any 24-hour period under any circumstances

Timing, Food, and Alcohol: What Affects How Well It Works

Even if you are taking the right dose, timing and lifestyle factors can dramatically affect how well sildenafil works. The medication should ideally be taken on an empty stomach or after a light meal. Consuming a large, fatty meal immediately before taking sildenafil can delay absorption by up to two hours, which is a common but easily overlooked reason why men report that their tablets do not appear to be working. For most men, the optimal approach is to take sildenafil approximately 30 to 60 minutes before anticipated sexual activity, ideally having not eaten a heavy meal within the preceding two to three hours.

Alcohol is another significant factor. Moderate alcohol consumption — one to two units — is unlikely to seriously interfere with sildenafil's effectiveness, but heavy drinking can worsen erectile dysfunction independently and also compound the blood pressure-lowering effects of the medication. In 2026, NHS guidance continues to emphasise that lifestyle factors including alcohol, smoking, and cardiovascular health are closely interconnected with erectile function, and optimising these alongside treatment gives the best outcome. If you regularly find sildenafil to be less effective than expected, it is worth reviewing your alcohol intake and considering whether stress, anxiety, or relationship factors may also be contributing.

  • Take sildenafil 30–60 minutes before sexual activity for best results
  • Avoid large or fatty meals immediately before taking your tablet
  • Limit alcohol to one to two units when using sildenafil
  • Sexual stimulation is required — sildenafil does not cause an automatic erection
  • Grapefruit and grapefruit juice can interact with sildenafil and should be avoided

Dose Adjustments for Older Adults and Special Groups

Certain groups of people require careful consideration when it comes to sildenafil dosing. Men aged 65 and over are typically advised to start at the lowest dose of 25mg. This is because age-related changes in liver and kidney function mean the body clears the medication more slowly, leading to higher plasma concentrations compared with younger men on the same dose. Starting low reduces the risk of side effects including orthostatic hypotension — a sudden drop in blood pressure when standing up — which can be particularly problematic in older adults.

Men with hepatic impairment (liver disease) or significant renal impairment should also begin at 25mg under medical supervision. Those taking certain medicines including alpha-blockers for prostate problems or blood pressure, antifungal drugs such as ketoconazole, or HIV protease inhibitors may need to reduce their sildenafil dose significantly due to pharmacokinetic interactions that raise sildenafil blood levels. Sildenafil Teva and other generic forms are bioequivalent to branded Viagra, so the same dose adjustments apply regardless of which manufacturer's product you use.

  • Men aged 65 and over: start with 25mg
  • Liver impairment: begin at 25mg, increase only under medical supervision
  • Kidney impairment: 25mg starting dose recommended
  • Men using alpha-blockers: a lower starting dose and careful titration is essential
  • Inform your prescriber of all current medications before starting sildenafil

What to Do If Sildenafil Is Not Working

One of the most frustrating experiences for men using sildenafil is when it does not seem to produce the desired effect. Before concluding that the medication is ineffective for you, it is worth considering some of the most common reasons why sildenafil may underperform. The most frequent mistake is taking the tablet too soon after a heavy meal, meaning absorption is delayed. Another common issue is not allowing sufficient time — sildenafil requires up to 60 minutes to reach peak plasma concentration, and some men take it only 10 to 15 minutes before activity expecting instant results.

Psychological factors are also highly relevant. Sildenafil only works in the presence of sexual stimulation. If anxiety, stress, or relationship difficulties are significant, they can prevent the psychological arousal that is necessary for the drug's pharmacological effects to translate into an erection. If you have tried your dose correctly on at least four separate occasions under reasonably relaxed conditions and it is still not effective, speak to your prescriber. They may increase your dose, switch you to a different medication such as Cialis (tadalafil), which has a longer duration of action, or refer you for further investigation if an underlying cause is suspected.

  • Ensure you are taking sildenafil correctly — on a light stomach, 30–60 minutes beforehand
  • Try your dose at least four times before deciding it is ineffective
  • Address stress, anxiety, and relationship factors where possible
  • Consider switching to a longer-acting PDE5 inhibitor if on-demand timing is inconvenient
  • Ask your prescriber about dose escalation to 100mg if 50mg consistently underperforms

Sildenafil Safety, Side Effects, and Drug Interactions

Understanding the safety profile of sildenafil is just as important as knowing the correct dose. The most commonly reported side effects include headache, facial flushing, indigestion, nasal congestion, and visual disturbances such as a temporary blue-tinged or blurred vision. These effects are generally dose-dependent, meaning they are more likely and more pronounced at higher doses. Most side effects are mild and resolve on their own within a few hours. Reducing from 50mg to 25mg often eliminates or significantly reduces them while still providing meaningful benefit for many men.

There are also important contraindications that every man should be aware of. Sildenafil must never be taken alongside nitrate medicines — including glyceryl trinitrate (GTN) sprays or tablets used for angina — because the combination causes a dangerous and potentially life-threatening drop in blood pressure. Vardenafil generic Levitra and other PDE5 inhibitors share the same contraindication. If you are unsure whether any of your current medications are nitrates, speak to a pharmacist before taking sildenafil. It is also contraindicated in men who have recently suffered a heart attack or stroke, and in those with severe hypotension or hypertension.

  • Common side effects: headache, flushing, nasal congestion, indigestion, visual changes
  • Side effects are more likely at 100mg — reducing the dose often helps
  • Never take sildenafil with nitrate medicines — this is a serious contraindication
  • Avoid if you have recently had a heart attack, stroke, or severe cardiovascular event
  • Priapism (prolonged erection lasting more than four hours) requires urgent medical attention

Sildenafil Dosage Comparison Table

Dose Who It Is For Timing Before Activity Key Considerations Maximum Frequency
25mg Men aged 65+, liver/kidney impairment, those on interacting medicines 30–60 minutes Lowest effective dose; reduces side effect risk in sensitive groups Once in 24 hours
50mg Most adult men as a starting dose 30–60 minutes Standard starting dose; effective in the majority of men Once in 24 hours
100mg Men where 50mg is ineffective and well tolerated 30–60 minutes Maximum licensed dose; higher incidence of side effects Once in 24 hours

It is worth noting that products such as Viagra Connect 50mg are available without a prescription at pharmacies for eligible men, but the same dosing principles and contraindications apply. Always read the patient information leaflet carefully and consult a pharmacist or prescriber if you have any questions about your individual suitability.

For men who find on-demand sildenafil inconvenient due to its relatively narrow timing window, longer-acting alternatives such as Tadalafil Teva — which can remain effective for up to 36 hours — may offer a more flexible approach to managing erectile dysfunction. Discussing the full range of options with your prescriber allows you to find the treatment that fits your lifestyle and health profile most effectively.

Key Takeaways

  • The standard starting dose of sildenafil for most men is 50mg — never take more than one tablet per day
  • Doses can be adjusted between 25mg and 100mg based on effectiveness and side effects under prescriber guidance
  • Take sildenafil 30 to 60 minutes before sexual activity on a light stomach for the best results
  • Sildenafil must not be taken alongside nitrate medicines due to the risk of severe blood pressure reduction
  • If your current dose is not working after several correct attempts, speak to your prescriber about dose adjustment or alternative ED treatments

When to Seek Professional Advice

You should seek professional advice from a pharmacist or prescriber if you are unsure which dose of sildenafil is right for you, if you experience troublesome side effects that are affecting your quality of life, or if the medication does not appear to be working after several correct attempts. Urgent medical attention is required if you experience an erection lasting longer than four hours (priapism), a sudden loss of vision or hearing, severe chest pain, or a significant drop in blood pressure causing dizziness or fainting after taking sildenafil.

If you have not yet been assessed for an underlying cause of your erectile dysfunction, this is also an important step. ED can sometimes be an early marker of cardiovascular disease, diabetes, or hormonal imbalance, and a thorough clinical assessment can identify and address any contributing conditions. Men with complex medical histories, multiple medications, or significant cardiovascular risk factors should always have their sildenafil treatment supervised by a prescriber rather than managing it entirely independently. You can speak confidentially to one of our UK-based prescribing pharmacists at Cured Pharmacy for personalised, professional guidance.

Scientific References

  1. Electronic Medicines Compendium (eMC). Sildenafil 50mg Film-coated Tablets — Summary of Product Characteristics. medicines.org.uk [Accessed 12 August 2026]
  2. British National Formulary (BNF). Sildenafil — Prescribing Information. bnf.nice.org.uk [Accessed 12 August 2026]
  3. NHS. Sildenafil (Viagra) — How and When to Take It. nhs.uk [Accessed 12 August 2026]
  4. Sildenafil 50mg and 100mg film-coated tablets – Summary of Product Characteristics, Electronic Medicines Compendium (EMC), Pfizer, 2023 [Accessed 12 August 2026]
  5. Cardiovascular disease: risk assessment and reduction, including lipid modification – NICE Clinical Guideline CG187, NICE, 2023 [Accessed 12 August 2026]
  6. Sildenafil monograph – British National Formulary (BNF), NICE/BMJ Group, 2024 [Accessed 12 August 2026]
  7. Sildenafil (Viagra) – Public Assessment Report, Medicines and Healthcare products Regulatory Agency (MHRA), 2012 [Accessed 12 August 2026]
  8. British Society for Sexual Medicine (BSSM) Guidelines on the Management of Erectile Dysfunction in Men, Hackett G et al., 2018 [Accessed 12 August 2026]
  9. Sildenafil: an orally active type 5 cyclic GMP-specific phosphodiesterase inhibitor for the treatment of penile erectile dysfunction – Boolell M et al., British Journal of Urology, 1996; cited in BMJ 2000 [Accessed 12 August 2026]

Find the Right Sildenafil Dose for You

Browse our full range of clinically approved erectile dysfunction treatments, reviewed by UK-based prescribers and delivered discreetly to your door.

Buy Now

Frequently Asked Questions

How long does sildenafil take to work?

Sildenafil typically takes between 30 and 60 minutes to start working. It is recommended to take it approximately one hour before sexual activity, on an empty stomach where possible, to allow the medication to be absorbed fully and reach its peak effect.

Is it safe to take sildenafil every day?

Taking sildenafil every day is not typically recommended for standard on-demand use. Most men take it as needed, no more than once in 24 hours. Daily low-dose regimens do exist for certain conditions, but this should only be followed under direct guidance from a prescribing clinician.

Can you take sildenafil with alcohol?

Taking sildenafil with alcohol is not recommended in large amounts. Alcohol can significantly reduce the effectiveness of sildenafil and increase the risk of side effects such as dizziness, flushing, and a dangerous drop in blood pressure. Small amounts of alcohol are generally considered acceptable, but heavy drinking should be avoided.

What is the correct dose of sildenafil for erectile dysfunction?

The correct dose of sildenafil for erectile dysfunction in most adult men is 50mg taken as needed, approximately one hour before sexual activity. Depending on effectiveness and tolerability, the dose may be adjusted to 25mg or increased to a maximum of 100mg, but only once per 24-hour period.

Back to blog