Sildenafil 100mg Tablets (Generic Viagra)

Sildenafil Tablets (25mg, 50mg & 100mg)

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Sildenafil tablets are available to buy from The Independent Pharmacy Online Doctor service, following a free consultation, to help to treat erectile dysfunction in men.

Sildenafil tablets are a generic treatment for erectile dysfunction (ED) in men. Sildenafil was first released under the well-known brand name Viagra, the ‘blue pill’ that has become iconic in the treatment of impotence. Once the patent on Viagra expired in 2013, generic treatments could be produced by drug manufacturers at a significant discount. Each manufacturer now produces different sizes and shapes of Sildenafil tablets, however they all contain the same active ingredient and should produce the same effect. Sildenafil is a PDE-5 inhibitor that treats erectile dysfunction by relaxing the blood vessels that feed blood to the penis, causing them to widen. This dilation allows a greater flow of blood to the penis, enabling it to become successfully erect.

Sildenafil 50mg tablets are the starting dose for patients who have not taken Sildenafil or other erectile dysfunction treatments before. Sildenafil 50mg is normally sufficient strength to treat most cases of ED however, as with all ED medicines, Sildenafil isn’t always successful the first time you take it, it can take a few attempts for your body to get used to the treatment. It is recommended to take Sildenafil at least eight times to allow it to build up a full effect before switching to a different erectile dysfunction treatment.

Sildenafil 100mg tablets are the highest dose for patients who have tried Sildenafil or other erectile dysfunction treatments before, without achieving satisfactory results. If you have tried Sildenafil 50mg, increasing the strength to 100mg can improve symptoms where 50mg is ineffective. 

Sildenafil 25mg tablets are the lowest strength of Sildenfail/Viagra available. Sildenafil 25mg tablets are normally used in patients who have experienced side effects when taking the starting dose of Sildenafil or Viagra 50mg tablets. Although they are the lowest strength treatment, Sildenafil 25mg tablets can still successfully treat ED in many patients with the lowest chance of side effects. Sildenafil 25mg tablets should, for those whom the 50mg strength are unsuitable, resolve the symptoms of erectile dysfunction. Even if the cause is psychological, its effect can help to break the cycle of anxiety associated with being unable achieve and maintain a satisfactory erection. 
Sildenafil increases the blood flow to the penis helping to achieve and maintain a satisfactory erection. Sildenafil will only help to produce an erection if you are sexually aroused, it will not help to get an erection without stimulation.

Sildenafil is the name of the drug contained in the branded medicine Viagra. Now that the patent on Viagra has expired other companies may make ‘generic’ versions of the drug, however they still must receive a product licence from the MHRA ensuring their safety. Due to increased competition ‘generic’ Sildenafil is available at a much lower price but still has the same effect and quality you would expect from a branded medication.

Pharmacist tip: Sildenafil should be taken 30 minutes to 1 hour before sexual intercourse. It lasts for 4 – 5 hours and you should try to avoid high fat meals around the same time as it may reduce the effectiveness of Sildenafil.

  • You should take one Sildenafil tablet at least 1 hour before sex.
  • Sildenafil can take up to an hour to take effect in some men, although it can take effect in as little as 20 minutes in some men.
  • Sildenafil can produce an effect for up to 4 – 5 hours.
  • You should never take more than tablet for erectile dysfunction (Viagra, Cialis, or Levitra) in a 24-hour period.
  • You should take Sildenafil on an empty stomach and try to limit your alcohol intake to ensure it remains effective.
Sildenafil does not always work for everyone the first time they use it. If this is the case you should not give up, guidance states that you should try your current dose of Sildenafil at least 8 times before trying an alternative treatment. If you find Sildenafil effective and do not experience any serious side effects you can request a repeat order via your online account. If you followed the above guidance and still find Sildenafil ineffective you may wish to try a different medicine such as Cialis, Spedra or Levitra. 

If you do experience side effects from Sildenafil they may include headache, flushing, light headedness and rarely a stuffy nose or indigestion. Sildenafil has a small risk of nausea, vomiting, diarrhoea, and skin rash as with all medicines. Please read the Patient Information Leaflet enclosed with your medicines for a full list of side effects.

If you experience any adverse effects from taking your prescribed medicine it is important to let us know immediately. Please log in to your online account and message one of our healthcare professionals or alternatively call us on 0333 2200 519. In a medical emergency you should contact the emergency services or go straight to your local Accident & Emergency.

Sildenafil tablets may not be suitable if any of the following apply:

  • You suffer from heart disease or heart rhythm problems
  • You have had a heart attack or stroke within the last six months
  • You have high or low blood pressure
  • You suffer from liver or kidney disease
  • You are a haemophiliac
  • You suffer from sickle cell anaemia or leukaemia
  • There is a physical deformity of the penis
  • You suffer from retinitis pigmentosa
  • You have a stomach ulcer.

If any of the above apply, it is important to let your doctor know so they can judge whether Sildenafil tablets will be safe for you to use.

Sildenafil tablets can lower the blood pressure. For most men this isn’t a concern. However, this effect on blood pressure can be exaggerated if Sildenafil is taken with a nitrate drug, such as Isosorbide or Glyceryl Trinitrate (GTN). If taking nitrate drugs then Sildenafil tablets should not be used. Sildenafil tablets should be used in caution if combined with alpha blockers due to the potential hypotensive effects.


Each Sildenafil tablet contains sildenafil as the active ingredient at a strength of either 25mg, 50mg or 100mg.

Each tablet also contains: microcrystalline cellulose, calcium hydrogen phosphate anhydrous, croscarmellose sodium, megnesium stearate, poly(vinyl alcohol), titanium dioxide (E171), macrogol 3350 & talc. 

Please note that different manufacturers may use different inactive ingredients. Please contact us for specific details or if you require a specific brand.

Need to know more about Erectile Dysfunction (ED)?

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Frequently Asked Questions

  • How does Sildenafil work?

    Sildenafil, like other ED treatments, works to expand the blood vessels that feed the penis. Normally, in men who suffer with erectile dysfunction, the blood vessels are narrowed and do not allow sufficient blood flow to the penis. Without adequate blood flow to the penis, a satisfactory erection cannot be achieved.

    By opening the blood vessels that feed the penis, Sildenafil allows the required amount of blood to enter the penis for a strong erection to be achieved.

    It is important to note that Sildenafil does not produce an erection; it simply allows one to occur naturally. Whilst taking Sildenafil you still need to have sexual stimulation to produce an erection.

  • What dose should I take?

    The dose of Sildenafil that you take will depend primarily on whether you have taken Sildenafil (Viagra) or another erectile dysfunction treatment before.

    If you have not tried an erectile dysfunction treatment before, you should start by trying Sildenafil/Viagra 50mg tablets and then adjust the dose according to your response.

    If you have taken an erectile dysfunction treatment before you can convert the doses roughly in the following way:

    Low strength

    • Viagra/Sildenafil 25mg
    • Cialis 5mg
    • Levitra 5mg
    • Spedra 50mg

    Regular Strength

    • Viagra/Sildenafil 50mg
    • Cialis 10mg
    • Levitra 10mg
    • Spedra 100mg

    High Strength

    • Viagra/Sildenafil 100mg
    • Cialis 20mg
    • Levitra 20mg
    • Spedra 200mg

    For example, if you have previously taken Cialis 20mg successfully and you wish to try Viagra or Sildenafil, you may wish to start with Viagra/Sildenafil 100mg.

  • Does Sildenafil start working straight away?

    For most men, Sildenafil will start to work around 30 minutes after it is taken, although it can produce an effect after anywhere from 20 – 60 minutes.

    The time it takes to kick in can vary from person to person, as well as being influenced by other outside factors. If Sildenafil is taken with a heavy or high-fat meal, or with high amounts of alcohol, it can take longer to have an effect and may even be less effective.

  • Does Sildenafil have any side effects?

    Like all medicines, Sildenafil can cause side effects. The good news is that they don’t affect everyone and are usually very mild if they are experienced. Suffering from side effects when taking Sildenafil is a good sign that the dose may be too high. If you do experience mild side effects you should consider reducing the dose you are taking.

    If you experience side effects they may include:

    • Flushing
    • Headaches
    • Feeling light headed
    • Congestion
    • Indigestion

    If you experience any serious side effects, such as chest pain, dizziness, facial swelling or skin reactions whilst taking Sildenafil you should seek medical attention immediately.

    If you have an erection for more than 4 hours you should seek medical attention.

    You can read a full list of side effects in the Patient Information Leaflet enclosed with Sildenafil.

  • How regularly can I take Sildenafil?

    Sildenafil can be taken as often as once daily, although this is not normally required. You should not take more than one Sildenafil tablet or other erectile dysfunction treatment in a 24-hour period.

  • How effective is Sildenafil?

    Sildenafil is thought to be effective at producing an erection in around 75% of men suffering from erectile dysfunction. It is the most well-known and popular erectile dysfunction tablet that has rightly gained a reputation as an effective, trusted treatment.

    Many men find that the starting dose of 50mg is a suitable dose however it can be increased to 100mg if required.

  • What happens if Sildenafil doesn’t work?

    It can take a number of attempts at using Sildenafil before it is effective. It is recommended to try taking Sildenafil on 8 separate occasions before increasing strength or trying a different ED tablet. Those that find Viagra/Sildenafil ineffective may wish to try an alternative ED treatment such as Cialis, Levitra or Spedra.

    Although most tablets for erectile dysfunction have a similar mechanism of action, some men may respond differently to individual treatments. If one tablet is ineffective, you may find you are more sensitive to a different treatment.

  • Are there any alternatives to Sildenafil?

    If you find Sildenafil (Viagra) ineffective, or you would prefer to try a different ED treatment for whatever reason, The Independent Pharmacy supplies a number of alternatives. These are:

    Cialis – Cialis contains the drug tadalfil and has a longer duration of action than Sildenafil; it can last for up to 36 hours. Cialis is the second most popular ED treatment after Sildenafil (Viagra).

    Levitra – Levitra contains the drug vardenafil and is similar to Sildenafil in many ways. It is thought that Levitra may be more effective for men who are suffering with ED as a secondary effect of diabetes.

    Spedra – Spedra is the newest erectile dysfunction treatment available and contains the drug avanafil. It is claimed to be the fastest acting treatment with it producing an effect in as little as 15-20 minutes.

    When looking for alternative to Sildenafil/Viagra you should always stick to licensed medicines that have been proved to be effective and undergo a strict manufacturing process. Erectile dysfunction treatment is a big market and there are thousand’s of unlicensed tablets and supplements available. Many of these undergo no regulation so you have no idea whether they work, or what you are taking!


  • How long will my erection last?

    Your erection should last for as long as there is sexual stimulation. As Sildenafil only gives you the ability to achieve an erection, rather than producing an erection itself, your erection should last for a normal period of time.

    You may find that the amount of stimulation required to achieve an erection is lower than usual and therefore you achieve an erection more easily or it lasts slightly longer than normal.

    Sildenafil should not produce an erection that lasts for long periods of time without subsiding. An erection that lasts for more than 4 hours requires immediate medical attention.

  • Can women take Sildenafil?

    Sildenafil is designed to treat erectile dysfunction in men by opening the blood vessels that supply the penis. It is not intended or licensed for use in women.

    Although there are reports of women using Sildenafil and having an increased sex drive or other effects, this is unlikely to be true for most women. Any effects felt are likely to be due to a placebo effect and women taking Sildenafil are more likely to experience side effects rather than any desired results.

  • Is there anything women can take instead of Sildenafil?

    There are currently no licensed treatments for women to take that would produce a comparable effect to that of Sildenafil in men.

    There is currently a drug in clinical trials, flibanserin, which may offer some improvement for women suffering with lack of sexual desire. It has recently been approved for use in America by the FDA and is due to be reviewed by the European Medicines Commission in the next 18 months.

  • Can I split or break pills in half?

    We do not recommend that you break Sildenafil tablets in half. This is because tablets are not always scored for accurate breaking and you are not always guaranteed to get the dose you want.

    As Viagra/Sildenafil tablets are available in a range of strengths (25mg, 50mg & 100mg), we would recommend that you purchase the strength that you require, even if this means purchasing more than one strength of tablets.


  • Does Viagra delay ejaculation?

    Sildenafil does not have any direct effect on the time it takes to reach climax. It is designed to treat erectile dysfunction and not to prolong the time to ejaculation.

    Some men may find that because the amount of sexual stimulation required to produce an erection is lower, they have an increased time to ejaculation as a secondary effect. This is because achieving climax requires a mixture of mental and physical stimulation. Sometimes if an erection has been achieved with the aid of Sildenafil, it takes time for the mind to be relaxed and stimulated enough to reach ejaculation.

  • Does Sildenafil have an effect on male fertility?

    There are no studies currently available showing a link between Sildenafil and any change in male fertility. Although there may be many individual stories available on the Internet claiming a decrease (or increase!) in male fertility after taking Sildenafil, these are not supported by any scientific evidence.

  • Does alcohol have an effect on Sildenafil?

    Alcohol may prolong the time it takes for Sildenafil to have an effect after being taken. This will depend on the amount of alcohol consumed and other factors such as any food consumed.

    More importantly, alcohol decreases the sensitivity of nerves, including those in the penis. This makes it harder to produce a response to physical stimulation as sensations are dampened.

    It is not uncommon for men to experience some form of erectile dysfunction after consuming alcohol, especially after binge drinking. If you are already suffering with erectile dysfunction, high volumes of alcohol can make it less likely that treatment like Sildenafil will be able to effectively help you to produce an erection.

    If you are taking Sildenafil you will see best results if you avoid alcohol, or stick to very small amounts.

  • How is Sildenafil different to the supplements I can buy online?

    There are many supplements available online that claim to help to treat erectile dysfunction. They include L-Arginine, Yohimbe, Dihydroepiandosterone (DHEA), Panax Ginseng, Horny Goat Weed and many more.

    The difference between Sildenafil and these other supplements is that Sildenafil is a licensed medicine hat has been clinically proven is clinical trials to be both safe and effective. As a medicine, it also undergoes a strict manufacturing process to ensure that every pack meets the required standards for human use.

    On the other hand, supplements like the ones named above, do not require any clinical proof of effectiveness or safety. They do not have any manufacturing legislation to ensure they are properly produced.

    In short, not only is there no definitive proof that any of the supplements available are effective, more importantly there is not always any evidence that they are safe for human consumption. This is especially true as most require high doses to be taken. Additionally, many supplements do not contain the advertised ingredients, as noted in many prominent news stories where people have harmed themselves by taking unproven supplements that have been bought online.

    We strongly advise our customers to avoid using supplements for the treatment of erectile dysfunction and stick to proven, licensed medicines.

  • Do I need to be a particular age to take Sildenafil?

    There is no particular age of men that Sildenafil is most suitable for. Although erectile dysfunction becomes more common in men as they age, it can be experienced at any age.

    This is because as well as narrowing of the blood vessels supplying the penis, erectile dysfunction can also be caused by anxiety. ED in older men is more likely to be caused by physical causes like narrowing of the blood vessels, whereas in younger men it is more often due to physiological causes like anxiety.

    Although Sildenafil can be successfully used to treat erectile dysfunction caused by physiological issues, it will not treat the underlying causes. There may be underlying issues that need to be discussed with a psychologist or sex therapist.

  • Can I take Sildenafil if I have heart problems?

    Men with heart problems should use Sildenafil in caution. This is because Sildenafil can also widen the blood vessels that feed the heart, increasing the blood flow and putting the heart under increasing strain.

    Any men suffering with heart issues should always see their doctor to discuss taking Sildenafil or any other ED treatment. Suitability will depend on individual circumstances and the severity of symptoms; therefore your own doctor should initiate any treatment. This ensures that a safe and appropriate solution is found.

  • Are there any medicines that interact with Sildenafil?

    There are a number of medicines that should not be taken at the same time as Sildenafil/Viagra due to serious interactions. Whilst taking Sildenafil you should avoid:

    • Nitrates – These are commonly taken for angina or chest pain and may be in the form of tablets or a spray. Common drug names include glyceryl trinitrate and isosorbide mononitrate.
    • Poppers (amyl nitrate) – Poppers are commonly used as recreational drugs and are also known as ‘room odourisers’.
    • Protease inhibitors (HIV treatment) - These should only be taken with Sildenafil/Viagra under strict instructions from your doctor due to potentially serious interactions. Examples of protease inhibitors include ritonavir, indinavir and nelfinavir.
    • Alpha-blockers – These are used to treat high blood pressure or prostate enlargement. They can cause increased side effects and should only be taken with Sildenafil under instruction form your doctor. Examples of alpha-blockers include doxazosin, tamsulosin, and mirtazapine.

    If you experience any serious side effects such as dizziness, chest pain or an allergic reaction, you should seek medical attention immediately.

  • How much Sildenafil can I buy at a time?

    You can buy up to 32 tablets of Viagra or Sildenafil tablets online from The Independent Pharmacy. This ensure that men can buy sufficient quantities of Viagra or Sildenafil in one order whilst ensuring that we are can maintain the safe and responsible operating of our pharmacy.

  • Is it safe to buy Sildenafil online?

    It is safe to buy Sildenafil online as long as you are buying from a reputable source like a registered online pharmacy. There are a number of things to look out for when buying Sildenafil online to ensure you are buying from a reputable source, you can read about them here.

  • What are the advantages of buying Sildenafil online?

     There are a number of advantages to buying erectile dysfunction treatment online such as:

    • Discretion – Many men do not like to discuss their condition as they may find it difficult or embarrassing. Buying online from The Independent Pharmacy bypasses the need for a face-to-face consultation without sacrificing service or safety.
    • Price – Buying Viagra or Sildenafil online may prove to be more cost effective than paying for a private prescription from a clinic or GP and then paying on the high street.
    • Quantity – Most GPs normally only prescribe around two boxes of Sildenafil at a time due to financial pressures on the NHS. The Independent Pharmacy allows men to buy up to eight boxes of Viagra or Sildenafil at a time to ensure an adequate supply.
    • Convenience – It is becoming increasingly difficult to get an appointment with your GP and find time away from work or family pressures to get the treatment you require. Ordering online allows you to buy at a time that suits you without the need to leave your living room.
    • Expert information – Often in busy GP surgeries and pharmacies you can end up not getting all the information you require with your treatment. The Independent Pharmacy website is information packed with everything you need to know about your condition and treatment. Plus, if you can’t find what you’re looking for our healthcare experts are available free of charge by telephone and email.
  • What’s the difference between Viagra and Sildenafil?

    In July 2013 the exclusive license for Viagra expired. This meant that any licensed drug manufacturer could produce it, whereas before July 2013 it could only be produced by Pfizer.

    Sildenafil is now produced by a number of different companies. These include Accord, Actavis, Mylan, Pfizer, Teva, Sandoz, Zentiva. Should you want a specific generic sildenafil please contact us to request it.

    Viagra is perhaps one of the most widely recognisable branded prescription medicines, which – following its discovery by Pfizer in 1996 – revolutionised the treatment of erectile dysfunction.

    Following years of market dominance and sales worth billions of pounds, in May 2013 Pfizer’s patent for Viagra expired allowing other drug manufacturers to enter the market. This has lead to the wide availability of sildenafil (the active drug contained in Viagra) tablets, pushing prices down. These unbranded sildenafil tablets are known as ‘generics’ and can come with some public stigma and often attracting differing opinions that can leave those looking for erectile dysfunction treatment confused.

  • How does generic Sildenafil compare to branded Viagra?

    Both generic medicines (like sildenafil) and branded medicines (like Viagra) are all subject to strict regulatory control by the MHRA in the UK, requiring a UK or EU product licence number in order to be on the market. This means that the public can be confident in that medicines that are obtained from reliable sources such as pharmacies are held to strict standards of quality.

    Therefore, when comparing the same strengths of sildenafil tablets and Viagra they will contain the exact same amount of the same drug. They will also contain very similar, if not the same excipients – the extras that are required to make a complete tablet.

    This means that generics like sildenafil should have the same results as their branded equivalents as they contain exactly the same drug, at the same strength, subject to the same manufacturing requirements. This is similar to well known drugs such as ibuprofen – most people would prefer to take the cheaper generic ibuprofen tablets rather than more expensive branded Nurofen tablets that exert the same effect.

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