Viagra vs sildenafil: What’s the Difference?

Dr. Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 25 Nov 2022

Viagra and sildenafil are both prescription medications used to treat erectile dysfunction. They contain the same ingredients and work in the same way by improving blood flow to your penis, making getting an erection easier. While they work in the same way, these medications do differ in price, packaging, and how commonly they’re prescribed on the NHS.

Here, we compare these treatments and look at their benefits to help clear up when and why they may be prescribed.

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Viagra and sildenafil similarities

Viagra and sildenafil have different names, so you’d be forgiven for thinking that they were two completely different drugs. In fact, Viagra and sildenafil are identical in all of the following ways:

  • their active ingredients (sildenafil citrate)
  • dosages (drug strength)
  • efficacy (how well they work)
  • how long they take to start working
  • how long they work for
  • safety and side effects
  • the size of the packs they come in
  • restrictions based on your current health status or other medications you're taking

Active ingredient

Viagra and sildenafil both contain the same active ingredients, the main one being sildenafil citrate. Both tablets come in different strengths that range from 25mg to 100mg. The normal starting dose is 50mg. This dose is also available over-the-counter without a prescription under the name Viagra Connect. Your dose can be decreased to 25mg or increased to 100mg if you need it. You can find out what dose of viagra is right for you by speaking to your GP or a ZAVA doctor free of charge through your patient account.

Dosage

Viagra and sildenafil are both available in 25mg, 50mg and 100mg doses. The usual starting dose for Viagra and sildenafil is 50mg. This dose contains 5mg of the active ingredient sildenafil citrate. You can expect to get the same results from each type of treatment if you're taking the same dose.

How long they last and how quickly they work

It will usually take between 30 and 60 minutes before Viagra and sildenafil will start to take effect. Both treatments last for between 4 and 6 hours, depending on the dose taken and whether you have eaten before.

Side effects

The side effects of Viagra and sildenafil are the same because they share the same active ingredient. Common side effects are:

  • headaches
  • nausea
  • facial flushing
  • dizziness
  • stuffy nose
  • changes to vision (blurred vision, colour tinges)

These side effects are often mild and will usually go away on their own within a few hours. If you experience side effects that are unmanageable or do not go away, you should speak to your doctor. If you get a painful erection that lasts longer than 2 hours, you should seek immediate medical advice.

Why do they have different names?

It’s common for medicines to have more than one name. These are their generic name (usually the name of the active ingredient of the drug), and one or more different brand names. In this case, sildenafil is the generic name, and Viagra is one of the brand names, for a medication with the active ingredient sildenafil. In other words, Viagra is the brand name given to the generic medicine sildenafil.

Why do brands exist for medications?

When a new drug is discovered, the pharmaceutical company that discovers it takes out a legal patent so that other companies can’t market that same drug for a certain length of time. This means that they are the only people selling it on the market, and therefore have control over the pricing.

In 2013, Pfizer (the manufacturer of Viagra) lost their patent on Viagra, which allowed generic manufacturers to start producing their own versions. These were sold for a lower price and are now more commonly prescribed on the NHS.

Differences between Viagra and sildenafil

Price

Sildenafil is much cheaper than Viagra,averaging at 71p per tablet, whereas Viagra connect starts from £1.45 per pill and Viagra can be as much as £5 per pill. How much these medications cost can be affected by the dose, the number of tablets you’re buying and the price the pharmacy you're purchasing them from charges. Prices will also be affected by whether or not you have a private prescription or not.

Collage von den Packungen und Tabletten von Viagra und Sildenafil

Appearance

The packaging of Viagra will display the brand name and dosage, show off the Pfizer logo and have blue finishes. The packaging for sildenafil has either purple or burgundy finishes alongside the generic name and dosage. Viagra pills are bright blue and diamond-shaped. sildenafil tablets can be blue or white and are either round or teardrop shaped.

Availability on the NHS

Sildenafil is much more readily available on the NHS because it’s cheaper and works in the same way. Viagra is rarely prescribed on the NHS and you have to fall under strict criteria to get a prescription. However, Viagra Connect doesn’t require a prescription, so you can get it over the counter at your local pharmacy, but you’ll need to answer a few questions beforehand to make sure it’s safe and suitable for you. When you order from ZAVA, you will have to answer similar questions to make sure treatment is right for you before it’s dispatched.

Is Viagra better than generic Sildenafil?

No. Viagra and sildenafil are exactly the same medication and work in exactly the same way, so they are both just as effective as each other. If you have ED, both medications should improve your erections. The key difference between the medications is the price. Viagra is much more expensive than sildenafil.

How do I choose between Viagra and sildenafil?

If you’re looking for an NHS prescription and want to save money on your ED medication, then sildenafil will be the best choice for you. It’s difficult to get an NHS prescription for Viagra, but you can still get it prescribed if you’re happy to pay full price. If you would rather purchase your ED pills over the counter, then Viagra Connect is your only option.

Viagra and sildenafil FAQs

Which one is better for me?

Both medications work in the same way and contain the same active ingredient, so there are very similar reviews from both options. The main reasons for choosing one over the other would be if you were allergic to any of the ingredients in each medication or if you’re looking for a cheaper option when comparing the two.

What are the differences between Viagra and sildenafil compared with Cialis?

Viagra and sildenafil are ED treatments that contain the same active ingredient, whereas Cialis is an ED treatment that contains the active ingredient tadalafil. Both sildenafil citrate and tadalafil work by relaxing the blood vessels in the penis, allowing a better blood flow to your penis to make getting an erection easier.

So, what about Cialis vs. Viagra? There are a few differences between these medications beyond the active ingredient. Cialis is available in more doses, it’s available in four different regular doses (2.5mg, 5mg, 10mg, 20mg). It’s also available as Cialis daily, which is a tablet you take daily so you’re able to get erections more easily at any time, regardless of whether you’ve just taken a pill. Cialis also starts working faster than Viagra, getting to work in just 30 minutes, and it can last for up to 36 hours.It is important to note, that Cialis is slightly less effective than Viagra, working for between 60 and 70% of people who take it.

Is sildenafil 100mg the same as Viagra 100mg?

Yes, as sildenafil and Viagra contain the same ingredients and work in exactly the same way, both of these doses would have an identical effect.

Does sildenafil last longer than Viagra?

No, both sildenafil and Viagra normally last between 4-6 hours but can last for up to 12. Both medications peak and work their best an hour after taking them.

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Medically reviewed by:
Dr Babak Ashrafi Clinical Lead for Service Expansion

Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.

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Last reviewed: 25 Nov 2022





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