What does Viagra do?

Reviewed by Dr Gigi Taguri

Viagra is a well-known brand of medicine used to treat erectile dysfunction (also known as “impotence”). Commonly referred to as “the little blue pill”, its name is famous around the world.

However, many people still aren’t familiar with how it works and may often find themselves asking the question “What exactly does Viagra do?”. In this article we’ll explain what Viagra does and whether it’s safe for you.  

What is Viagra?

Viagra is a blue tablet containing the active ingredient “sildenafil citrate”. It is taken by men who suffer from erectile dysfunction. It’s taken about an hour before sex to help gain and maintain an erection. Despite the common misconception, Viagra is not an aphrodisiac - any man taking Viagra will need to be sexually aroused in order to achieve an erection.

Viagra is commonly available in three different dosages: 25mg, 50mg and 100mg. The dosage you can take will vary depending on the person. Sometimes it may need to be increased or decreased by your doctor.  

How does Viagra work?

To understand what Viagra does and how it works, you must first understand the way in which a man gains an erection.

When the brain becomes aroused, it sends signals to the penis which leads to the release of a chemical called cGMP. This chemical relaxes certain muscle cells in the erectile tissue of the penis, allowing blood-flow to increase to that area.

After ejaculation, the body releases an enzyme called PDE-5, which breaks down cGMP causing the loss of the erection. Viagra, and other ED medicines, work by inhibiting the effect of PDE-5 thus increasing the blood flow to the penis and making it easy to gain and maintain an erection.

How long before sex should you take Viagra?

For Viagra to work properly, it should be taken an hour before sex on an empty stomach. You will need to be sexually aroused to achieve an erection. You should avoid drinking alcohol before taking Viagra, as this can limit its effectiveness. 

What happens when you take Viagra?

You may have heard that taking Viagra gives you an instant, spontaneous erection. But, that’s not quite how it goes. Let's take a closer look at the Viagra timeline: 

What does Viagra do to your body?

Viagra works with enzymes in your body to increase blood flow to your penis. Helping you gain and maintain an erection. Find out more about the chemical process involved below: 

How does Viagra make you feel?

Viagra won’t change how you feel or think about or during sex. It helps you get and keep an erection. It could mean you can get an erection when you normally couldn’t or it’s a lot firmer than your usual erections. Which may boost your confidence or make sex more enjoyable.

Does Viagra make you last longer?

Viagra won’t make you last longer in bed, see our guide for helpful tips. But, as shown in independent studies, Viagra lasts for around four to six hours. Typically, it takes effect 30-60 minutes after you take it. You'll need to be sexually aroused and not have eaten a fatty meal within the past few hours.

Once the effects of Viagra have worn off, it is important that you do not take any more within 24 hours. This means you should not take Viagra in combination with any other ED tablets. 

What can I do to make Viagra work faster?

Viagra usually starts to work in 30 minutes. One study found that participants got an erection in as little as 12 minutes. You’ll need to be sexually aroused. To help Viagra work faster you can take it on an empty stomach. Taking Viagra after a large fatty meal can make it take longer to have an effect.  

How effective is Viagra?

In clinical trials, a 25mg dose of Viagra was effective for 62% of men. A 100mg dose of Viagra was effective for 82% of men. However, Viagra won’t work on its own. You need to be sexually aroused to have an erection. Taking it sober on an empty stomach can bring the best results.  

How does Cialis work compared to Viagra?

Most ED treatments last for the same amount of time as Viagra, however Cialis (tadalafil) is one exception. If you are looking for an erectile dysfunction medicine that will last for longer than six hours, then Cialis may be right for you. Taken correctly (30 minutes before sex, without alcohol) Cialis can last for up to 36 hours. 

The table below gives some more details about the effects of ED medicines: 

Finding the right ED medication for you will be influenced by your health. Our clinicians will review your online questionnaire to make sure any treatments are safe for you to take.   

Is Viagra safe?

While most men with erectile dysfunction should be able to use Viagra. There are some exceptions. If you fall into the following categories, you shouldn't use Viagra or any other ED medicines.

Viagra is not safe if you:

• are taking nitrates
• use recreational drugs that contain nitrates, such as poppers
• have severe heart or liver problems
• have recently had a stroke or heart attack
• have taken alpha-blockers within the past 6 hours
• have already taken Viagra or another type of ED medicine within the past 24 hours
• don't experience erectile dysfunction
• are a woman 

How to make sure it’s safe

You should only get Viagra through a prescription from a medical professional. Although there are a lot of websites which offer cheap erectile dysfunction medicines. It's almost impossible to be sure where these come from and whether they are safe to take.

If you do want to start taking Viagra, speak to your GP. Or use a trusted and regulated Online Doctor service. 

Which dosage is safe for me?

When you order Viagra a doctor will prescribe the safest dosage for you. If you find you're having unwanted side effects or it's working for you, you may need to change your dosage.

Keep in mind that you will need to try a dosage of Viagra at least eight times before changing to a higher dosage. Sometimes it takes a while to begin working. 

What are the side effects of Viagra?

Most men can take Viagra without experiencing any side effects. However, as with all medicines, there are some risks. These include:

• nausea
• headache
• blocked nose
• indigestion
• flushing (redness in the face)
• dizziness
• blurred vision

For a full list of side effects, refer to the information on your medication. If you are experiencing frequent unpleasant side effects from Viagra, stop taking it and speak to your doctor.

Conclusion

When it comes to what Viagra does there a few key takeaways:

• It won’t increase your sex drive or interest in sex
• It can help you get and keep an erection
• It can cause mild side effects which are usually temporary
• You’ll need a prescription to use Viagra 

To order Viagra from Online Doctor, visit our secure online clinic.

References

www.nhs.uk/medicines/sildenafil-viagra/
www.medicines.org.uk/emc/medicine/30907
www.medicines.org.uk/emc/product/9472/pil#gref
https://www.medicines.org.uk/emc/product/8725#gref
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1874251/
https://bpspubs.onlinelibrary.wiley.com/doi/pdf/10.1046/j.0306-5251.2001.00034.x