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What is Viagra tablets?

If you suffer from erectile dysfunction or impotence, then Viagra Connect may be an ideal treatment for you. Viagra Connect contains the same active ingredient as Viagra and takes about 30 - 60 minutes to begin working and can last up to 4 hours. 

Medicine type Phosphodiester type 5 inhibitor
Mechanism of Action  Increases blood flow to the penis when sexually stimulated. 
Active Ingredient Sildenafil
Effective Within 30-60 minutes
Pack Size 4-16 tablets
Strength Ingredient 50mg
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Sufyan Tahir

Authored by

Sufyan Tahir

Clinical Governance Lead

Registration Number: 2221275

Ubayd Ali

Reviewed by

Ubayd Ali

Superintendent Pharmacist

Registration Number: 2219322

NHS Pharmacist and founding member of HEBA, with years of experience in healthcare across innovative organisations.
Review Date 10 March 2026
Next Review 10 March 2028
Published on 10 March 2026
Last Update 10 March 2026

Overview

What Is Viagra?
Viagra (sildenafil) is a widely recognised prescription medicine for erectile dysfunction (ED), a condition where men find it difficult to achieve or maintain an erection. The key ingredient in Viagra tablets is sildenafil citrate, which works by increasing blood flow to the penis, thus helping to achieve a firm and lasting erection when sexually aroused. It's a safe and effective solution for many men experiencing ED, designed to improve sexual performance and confidence. Viagra is known for its quick action, usually taking effect within 30 to 60 minutes, and its effects can last for approximately 4 to 5 hours. It’s a prescription medication, ensuring that it's used under medical guidance to address erectile dysfunction effectively and safely.

Treating erectile dysfunction with Viagra
We understand that figuring out where to buy erectile dysfunction medication online can be a real minefield. Due to its popularity, Viagra (along with other erectile dysfunction medications) is often counterfeited or sold by unlicensed, untrustworthy retailers. Luckily, we provide a legal and safe way to buy Viagra online, and we can have it delivered directly to your door (in discreet packaging) by the next day.

Simply select your preferred medication and complete a quick questionnaire to discover if Viagra is suitable for you. Our qualified UK prescriber will review your answers and issue a private prescription if Viagra is suitable for you. They can also advise you on the most appropriate dosage and any known side effects. If Viagra isn't right for you, please get in touch with our team to explore other treatment options.

Order before 3pm for same-day dispatch in the UK.

What is erectile dysfunction?
Erectile dysfunction affects around 1 in 10 men, but it is treatable. Its medical definition is the inability to achieve or sustain an erection long enough for sexual intercourse. While there is no straightforward ED cure, Viagra can help men to achieve a firmer, harder erection and maintain a normal, healthy sex life.

There are many reasons why a man may experience ED or impotence. These include factors or conditions such as diabetes, heart disease, obesity, smoking, alcoholism, sleeping disorders, poor diet, high blood pressure, stress, depression, anxiety, low energy, or relationship problems. The reasons may be physical or psychological. It is most common in men aged 50 years and above, but it affects men at any age – even young men.

How Does Viagra Work
Viagra is a popular ED solution and treatment with a global reputation. Viagra tablets are manufactured by Pfizer and are the best-known brand for the treatment of erectile dysfunction (ED). Viagra 100mg tablets have a strong effect in increasing blood flow to the penis by widening the blood vessels, which helps in achieving an erection. This increase in blood flow to the penis is caused by the active ingredient sildenafil citrate and normally results in a satisfactory erection being achieved.

It usually takes 30 to 60 minutes for Viagra tablets to work, and the effect lasts about 4 to 5 hours. This allows them to be taken discreetly before they are required.

Does Viagra Work Every Time?
For the majority (around 70%) of men, Viagra is a highly effective treatment for ED that will continue to work no matter how often it is taken. The approved advice is to try sildenafil on at least eight separate occasions before switching to another medication. It may also be worthwhile to take Viagra when masturbating, as the issue may be purely psychological and unrelated to the effects of the drug.

However, if you’ve had success with Viagra tablets in the past but the drug isn’t working as well as it used to, this will need to be addressed. If your erections are softer than usual or harder to maintain now, other factors may be to blame. These include:

An anomaly — A simple case of bad luck. The treatment may have been taken incorrectly, or you may just need to wait a little longer before the drug takes effect.
Loss of efficacy — In rare cases, your body may become ‘tolerant’ to sildenafil. If your current ED medication isn’t helping you to achieve strong, long-lasting erections, it’s time to talk to your GP. They may recommend that you switch to another type of ED treatment, such as Cialis (tadalafil) or Levitra (vardenafil).
Drugs or alcohol — Drinking alcohol or taking certain recreational drugs can worsen the effects of your ED to the point of diminishing (or even eliminating) the effects of your medication altogether.

Viagra Dosage
Viagra 50mg tablets are the starting, standard dose for patients new to Viagra and are often the first erectile dysfunction treatment that many men try. Viagra 100mg pills are the highest dose of Viagra (sildenafil) available and are generally used when patients have tried Viagra 50mg tablets at least 8 times with limited success. If treatment with Viagra tablets is still unsuccessful after 8 attempts, it is more appropriate to try a different erectile dysfunction treatment, such as Cialis, Levitra or Spedra (avanafil).

Patients who find a strength of Viagra that works for them may wish to consider switching to the generic ED treatment Sildenafil, which is available at a significant discount following the expiry of Pfizer's patent on Viagra. Many men do not notice a difference between taking Viagra and generic sildenafil pills for ED.

Understanding ED, Viagra & Sex
Viagra 100mg tablets will, for most, resolve the symptoms of erectile dysfunction and impotence. As they open the blood vessels that supply blood to the penis, they are effective at treating the physical causes of erectile dysfunction. However, if the cause of ED is psychological, its effect can help to break the cycle of anxiety associated with being unable to achieve and maintain a satisfactory erection. If you suffer from ED due to psychological causes it is recommended that you discuss your condition with your GP or a sexual health therapist.

Viagra 100mg tablets will not cause sexual arousal. It is a common misconception that erectile dysfunction treatments have this effect. An erection cannot be achieved or maintained without the necessary sexual stimulation. To fully understand how Viagra works, it is first necessary to understand the mechanics of an erection. When a man becomes sexually stimulated, the nervous system in the erectile tissue of the penis starts to release nitric oxide. This triggers a reaction that relaxes the muscles in the penis. This muscle relaxation has two effects:

  1. The arteries in the penis widen, making it easier for blood to flow
  2. The erectile tissue fills with blood
    It's these two processes that result in a successful erection. Viagra helps by keeping the muscle-relaxing substance (cGMP) at the right level in the penis. However, if a man isn't sexually stimulated, then nitric oxide isn't released, and no cGMP will be produced, resulting in no erection.

Viagra Alternatives
It's important to note that Viagra isn't always successful the first time you take it. It is recommended to try taking Viagra at least eight times before trying a different erectile dysfunction treatment such as Cialis (see how it compares to Viagra here), Spedra (avanafil) or Levitra (vardenafil). And if you're looking rather for a topical treatment, you could consider Vitaros Cream.

You can also buy the generic and low-cost version of Viagra in the form of Sildenafil, which has exactly the same active ingredient (sildenafil citrate) and has been available in the UK since the expiration of the original Viagra patent in 2013.

There are a number of non-prescription steps you can take to treat Erectile Dysfunction, such as:

  • Changes to diet (cutting down alcohol and fat consumption)
  • Stopping Smoking
  • Reducing Stress
  • Counselling
  • Vacuum Devices (Penis Pumps)

Directions

How to Use Viagra
Guidelines state you should take one Viagra tablet at least 1 hour before sexual intercourse.
Viagra 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.
Viagra can produce an effect for up to 4 - 5 hours.
You should never take more than a tablet for erectile dysfunction (Viagra, Cialis, or Levitra) in a 24-hour period.
Avoid eating any foods before taking Viagra, and try to limit your alcohol intake to ensure it remains effective.
Viagra does not always work for everyone the first time they use it. If this is the case, you should not give up. Guidelines state that you should try Viagra at least 8 times before trying an alternative treatment such as Cialis, Spedra or Levitra. Depending on your response, you may need to increase or decrease your strength as appropriate.

If you find Viagra effective and do not experience any serious side effects you can request a repeat order via your online account.

Side Effects

Viagra Side Effects
If you do experience side effects from Viagra (sildenafil) they may include headache, blurred vision, flushing, lightheadedness and rarely a stuffy nose or indigestion. Viagra 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 at 0333 2200 519.

In a medical emergency, you should contact the emergency services or go straight to your local Accident & Emergency.

You or your partner should call 911 if you experience any of these medical emergencies (very rare):

  • Allergic reactions like trouble breathing, itching and swelling of your throat, face or tongue, or severe dizziness
  • Priapism (painful erection that lasts more than 4 hours)
  • Sudden decrease or loss of vision
  • Chest pains
  • Heart attack

Further Information

Verified customer reviews

Frequently asked questions

  • Does Viagra start working straight away?

    For most men, Viagra 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 Viagra 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.

  • How regularly can I take Viagra?

    Viagra can be taken as often as once daily, although this is not normally required. You should not take more than one Viagra tablet or other erectile dysfunction treatment in a 24-hour period. We wouldn’t recommend taking a dose of more than three to four tablets per week.

  • How effective is Viagra?

    Viagra 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 usual starting dose of 50mg is a suitable dose of sildenafil (Viagra). However, it can be increased to 100mg if required.

  • 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 Viagra?

    Viagra 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 Viagra 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 Viagra are more likely to experience side effects rather than any desired results.

  • 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 have an effect on male fertility?

    There are no studies currently available showing a link between Viagra 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 Viagra, these are not supported by any scientific evidence.

  • Can I take Viagra if I have heart problems?

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

    Any men suffering from heart issues should always see their healthcare provider to discuss taking Viagra 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.

  • Is it safe to buy Viagra online?

    It is safe to buy Viagra 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 Viagra online to ensure you are buying from a reputable source, you can read about them here.

  • What does Viagra look like?

    Viagra is traditionally a diamond-shaped tablet that is blue in colour. It has the letters VGR and the dosage engraved on one side, with the Pfizer logo on the other. They are never scored or white. Viagra comes in packs of four – it will never be supplied loose. This is how you know it’s genuine Viagra. Counterfeit Viagra may be a different shape, size or colour, and you may notice it has a flavour. When you buy Viagra directly through the Independent Pharmacy, you can rest assured that you’re getting the real deal.

  • Can you buy Viagra at Boots or over the counter?

    Yes, Viagra is stocked and available at Boots and most major pharmacies. But remember — you will always need a prescription from your GP, and you can’t just buy Viagra over the counter in the UK. At HEBA Online Pharmacy, we take care of the prescription for you to save you a trip to the GP!

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