What is Viagra? Vital specs and info

What is Viagra?

You’ve probably heard of it. The Little Blue Pill. And you probably know that it helps with erections. It’s seen as the “first” ED treatment to appear on the market, and it’s been used by millions of men. Because the pharma company Pfizer got there before anyone else, they own the Viagra brand name as well as the distinctive, diamond-shaped pill design. 

All of this has helped the Viagra pill become the biggest player in the ED field. But let’s put its status to one side for a moment. How does it work? The main ingredient in Viagra is something called sildenafil citrate, and it helps with erections by relaxing the blood vessels of the penis.

An erection from relaxed blood vessels?

It sounds counterintuitive, but it’s not — when your blood vessels are too tight, blood can’t get to the penis quite as well. Sildenafil citrate improves your circulation, and this allows you to get firmer erections that last long enough for sex. 

While it’s the brand-name treatment, there are other names for Viagra too. The product Sildenafil (with a capital S) is generic Viagra. Sildenafil works in exactly the same way as Viagra but is made by different companies. While it contains the same active ingredient, a Sildenafil pill can have a unique design and packaging depending on who makes it. And because it doesn’t come with that brand-name price tag, Sildenafil is usually cheaper.

Viagra and Sildenafil are taken as-needed, meaning you’ll pop a tablet around an hour before sex. It’ll work for about five hours, and you shouldn’t take more than one in a 24-hour period. Don’t worry, though — that doesn’t mean you’re going to have an erection for five whole hours. ED meds like Viagra and Sildenafil help you get an erection, but you still have to be aroused for them to work.

Page reviewed by:
Mr Craig Marsh
Mr Craig Marsh
Pharmacist Prescriber
Visit author profile
Last updated August 9, 2021
Viagra Sildenafil Citrate
Viagra is a prescription pill that helps you get and keep an erection.
  • Active Ingredient: Sildenafil
  • Administration Route: Oral
  • Dosage Form: Tablet
  • Drug Class: PDE5 Inhibitor
  • Available Strength: 20mg (generic only), 25mg, 50mg, 100mg
  • Dose Schedule: No more than once every 24 hours
  • Alcohol Warning: None
  • Breastfeeding Warning: N/A
  • Pregnancy Warning: N/A
  • Food Warning: May interact with grapefruit
  • Maximum Intake: 100mg
  • Prescription Status: Prescription-only

Some quick Viagra history

Although Viagra has been FDA-approved to treat erectile dysfunction for over two decades, it was originally developed in 1989 by two Pfizer scientists — Peter Dunn and Albert Wood — to treat high blood pressure and angina.[1]

Yes, the last name of one of the guys who invented Viagra is Wood.

Trials for Viagra as a treatment for heart disease got underway in the early 90s, but showed little promise. However, participants in the trials did notice an increase in the number of erections they were getting. This led to pilot studies of its use as an ED treatment. The FDA approved Viagra as an ED medication in 1998.[2]

Pfizer retained the Viagra patent for 15 years, until its expiration in 2013. This allowed other companies to start making their own versions of Viagra with the same active ingredient (like Sildenafil). Even Pfizer started producing a generic Viagra.

These days, sildenafil citrate (the main ingredient in Sildenafil and Viagra) is also sold as Revatio, a medication for pulmonary arterial hypertension, or PAH.

What does a Viagra pill look like?

The Viagra pill or tablet is blue in color, and shaped like a diamond. Viagra pills have “Pfizer” written on one side and the dosage on the other (so either VGR25, VGR50 or VGR100 to indicate 25mg, 50mg or 100mg doses).

What are the benefits of Viagra?

In terms of the benefits of Viagra for men, you’re getting a tried-and-tested ED treatment with a household name to boot. Most men find that Viagra works the first or second time they try, and there’s flexibility with the available doses: 25mg, 50mg and 100mg. If you find that the 25mg dose isn’t strong enough, you can switch to the 50mg tablet, and if this doesn’t work as well as you’d like it to, the 100mg option is there for you. 

Another string to Viagra’s bow is that it’s easy to use. You take one tablet one hour before sex and it should remain active in the body for up to five hours. So plenty of time to enjoy intimacy with your partner.

Can you only get Viagra for men?

Yes. Viagra pills are for men only. There is a medication for women called Addyi, which is sometimes known as “female Viagra,” but it’s used to treat a completely different issue and works in an entirely different way. While Viagra helps make sex physically possible, you still need arousal to get an erection. Addyi is prescribed to help increase arousal rather than impact the physical mechanics of sex, so it shouldn’t be confused with male Viagra.

What is Generic Viagra?

Sildenafil is the generic version of the ED treatment Viagra, which is made by Pfizer. Viagra has the same active ingredient (sildenafil citrate) but a specific look, branding, formulation and price. Sildenafil can be made by multiple companies and will have a different appearance, price and inactive ingredient list depending on the manufacturer. All Sildenafil is bioequivalent, though, which means it has the same active ingredient and works in the same way. 

Think of it like ibuprofen, the medication you might take for headaches. You can go to the store and pick up Advil, which is a brand-name version of ibuprofen and probably a bit more expensive. The store might also have several other types of ibuprofen, including their own line (likely the cheapest). These medications will all help you with your headache, but the size and color of the pill, the branding on the box and the inactive ingredients will all be a little bit different.

Sildenafil was released in 2013 after the Viagra patent expired, and as the generic, it tends to cost a lot less. So if you’re looking for a cheaper product, you may want to go with Sildenafil pills instead.

Sildenafil vs sildenafil citrate: what’s the difference?

Semantics, really. Sildenafil citrate is the name of the active ingredient in Viagra (and Sildenafil) whereas Sildenafil (with a capital ‘S’) is the generic version of Viagra — a medication containing sildenafil citrate. However, sometimes “sildenafil” is used as shorthand for sildenafil citrate. Depending on the sentence you see it in, you can usually figure out whether it’s referring to the medication or the ingredient. 

Although dosage can differ, all sildenafil citrate tablets should work just about the same, no matter what company makes them. The main differences between them will be the packaging, price and inactive ingredients.

What about Viagra Connect?

Viagra Connect is a 50mg dose of sildenafil that’s only available in the UK. (This means you can’t currently get Viagra Connect in the USA.) 

Pfizer launched Viagra Connect in the UK in 2018, and it’s a rebranded version of Viagra 50. It works in the same way as Viagra, and it’s got the same active ingredient in it.

The one big difference is that you don’t need a prescription to buy it, but it’s not an “over the counter” medication as such. While it’s available to purchase in pharmacies, you still need to speak with a pharmacist to make sure it’s safe for you to take. Because you can only get it in a 50mg dose, it won’t necessarily be the best choice for every man, but some may find it’s a little easier to get hold of as a non-prescription product.

How to take Viagra

Taking Viagra is simple. Just have your pill with a glass of water. It doesn’t matter if you take Viagra with food or not, and it doesn’t interact with alcohol — though alcohol can make ED worse, so consume it in moderation. 

To decide when to take Viagra, you’ll need to do a bit of mental planning about your night. It’s important to know how long before sex you should take Viagra, which is about sixty minutes. That’s how long it takes to become effective, but it doesn’t mean you’ll get an automatic erection in an hour — you still need to be aroused for Viagra to work.

Your medication will come with an informational pamphlet containing detailed instructions. Always read the pamphlet before taking Viagra for the first time.

How long does it take for Viagra to work?

Viagra kicks in within 30-60 minutes of taking it and is active in the body for up to five hours, although your age, diet and health can all impact on how long Viagra takes to work. A five-hour window means you don’t have to worry too much about timing your Viagra dose.

How much Viagra should I take?

You shouldn’t take more than one Viagra tablet over a 24 hour period. If you use Viagra and find that it doesn’t work as effectively as it should, or if you get any side effects, let your doctor know. They may decide to change your dose. 

Viagra comes in multiple dosages, from 25mg up to 100mg. This is a bigger range than with other ED drugs, so it’s easier to find the dose that’s right for you. The “typical” dose is 50mg, which is what you’ll normally start with when taking the drug for the first time.

The lower doses are better for people who experience side effects with 50mg, or who have risk factors (like diabetes) that make them prone to side effects. On the flip side, a doctor may prescribe the 100mg tablet if you’ve tried 50mg and it wasn’t strong enough.

How often can you take Viagra?

The daily Viagra dosage depends on what you’ve been prescribed by your doctor, but you shouldn’t use Viagra more than once a day. However there are other medications that can last longer (like a whole weekend), or that you take every day (so you’re ready to go whenever).

Does Viagra work?

Yes. Viagra works for about 3 in 4 men, so it’s pretty effective.[3] Viagra results in clinical trials reflect good performance too. For the 25mg dose, 62% of men found that it gave them better erections, while 74% of men taking the 50mg dose reported improved erections.[4] The 100mg dose also produced strong outcomes, with 82% of men experiencing greater erectile potency.

How long does Viagra last?

The effects of Viagra normally last for up to 5 hours, but this can vary from one person to the next, so the best way to know how long it’s active for you is to try it. 

Viagra duration also depends on a number of factors. If you’re over 65, you may find that it lasts for longer than 5 hours as your body doesn’t remove it from your system as readily. Drinking alcohol reduces blood flow to the penis, which makes it more difficult to get an erection. And your Viagra pill might need some extra time to kick in if you eat a big meal that’s high in fat versus taking it on an empty stomach.

If you feel that the effects of Viagra are not lasting long enough, you should discuss increasing your dose with your doctor.

Does Viagra work the first time?

Viagra works the first time (or the second) for most men who start out on the 50mg dose. 

Sometimes the 50mg dose can cause side effects such as a headache or feeling sick, and in these instances your doctor may recommend reducing your dose to 25mg. On the other hand, if you find that the 50mg dose isn’t giving you a sustained erection for long enough, it’s worth speaking to your physician about increasing your dose to 100mg provided you haven’t had any side effects on the 50mg tablet.

Does Viagra make you bigger?

No — and there aren’t any other tablets that can either. 

However, Viagra does help you reach “peak size.” So while it doesn’t give you any extra length or girth, Viagra can make your erections as firm as possible. Think of it like a medication that’s able to fully maximize what you’ve got.

It’s worth mentioning that any pills claiming to make your penis larger should be looked at with a lot of caution (and side-eye). They’re usually not licensed medications, and they can be very dangerous.

What should I do if Viagra isn’t working?

If you find that Viagra doesn’t work, talk to your doctor about switching to a higher dose. But if you’ve already had your dose adjusted and that hasn’t improved things, it’s worth exploring different ED medications. There are lots of ED products available with proven effectiveness, and you may have to try a few different options before determining the right medication for you when Viagra doesn’t work.

How does Viagra work?

Viagra and many other ED meds are what are called PDE5 inhibitors. PDE5 stands for Phosphodiesterase Type 5 and it’s an enzyme in the walls of your blood vessels. What happens when you take Viagra (and similar medications with the active ingredient sildenafil citrate) is that your blood vessels relax, so blood can get to where you need it most. Put simply, Viagra helps you get and maintain an erection.

Is Viagra safe?

Viagra is quite safe and has undergone rigorous scientific testing before being FDA-approved to treat erectile dysfunction. That said, it still has possible side effects as well as contraindications and interactions with other medications. Make sure to always read the product information that comes with your prescriptions before taking them, and talk to the doctor about your medical history and any other medications you take, including vitamins and recreational drugs, so they can make sure Viagra is safe for you. 

Does Viagra expire? Yes. Like all medications, your ED treatment will eventually expire. It won’t happen nearly as quickly as with your produce — the sildenafil shelf life is around two years. Still, if you’ve found an old bottle of expired Viagra jammed in the back of your medicine cabinet, it’s probably best to just get a new prescription. Old medication will likely be less effective, and it’s possible that it can grow mold or bacteria.

Store your Viagra between 68°F and 86°F, out of direct sunlight, so it stays safe and effective as long as possible.

Does Viagra make you last longer?

Does Viagra help with premature ejaculation? There’s some evidence to support this. However, the evidence isn’t 100% conclusive and Viagra isn’t prescribed to treat premature ejaculation. 

Although most studies of Viagra and its main ingredient, sildenafil, have focused on its treatment of erectile dysfunction, there are two that looked at whether Viagra can delay ejaculation. The first study[4] found that sildenafil is “very effective and safe to treat PE” and the second[5] that sildenafil increased confidence, the perception of ejaculatory control and overall sexual satisfaction.

So while you won’t get a sildenafil prescription for premature ejaculation, it’s possible that the medication will help you if you experience PE as well as erectile dysfunction. If you’re interested in this potential effect, talk to the doctor during your EveAdam consultation and they can give you more information and advice.


[1] Wilson, J. 2013. Viagra: the little blue pill that could. CNN health [online]. Available at: https://edition.cnn.com/2013/03/27/health/viagra-anniversary-timeline/index.html [Accessed 24 June 2021].

[2] EMC. 2021. Sildenafil 100mg film-coated tablets. Available at: https://www.medicines.org.uk/emc/medicine/30907 [Accessed 30 June 2021].

[3] Wagner, G., Montorsi, F., Auerbach, S., Collins, M. 2001. Sildenafil Citrate (VIAGRA) Improves Erectile Function in Elderly Patients With Erectile Dysfunction: A Subgroup Analysis. Oxford Academic. [online]. The Journals of Gerontology: Series A, Volume 56, Issue 2, 1 February 2001, Pages M113–M119. Available at: https://academic.oup.com/biomedgerontology/article/56/2/M113/563357 [Accessed 28 June 2021].

[4] Wang, W.-F., Wang, Y., Minhas, S. and Ralph, D.J. (2007). Can sildenafil treat primary premature ejaculation? A prospective clinical study. International Journal of Urology, 14(4), pp.331–335. Available at: https://pubmed.ncbi.nlm.nih.gov/17470165/ [Accessed 6 July 2021].

[5] McMahon, C.G., Stuckey, B.G.A., Andersen, M., Purvis, K., Koppiker, N., Haughie, S. and Boolell, M. (2005). Efficacy of Sildenafil Citrate (Viagra) in Men with Premature Ejaculation. The Journal of Sexual Medicine, 2(3), pp.368–375. Available at: https://pubmed.ncbi.nlm.nih.gov/16422868/ [Accessed 6 July 2021].