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Erectile Dysfunction
Looking for ED treatment? Viagra (sildenafil) is probably the most famous. Here’s everything you need to know about it and how to get it in Canada.

What is Sildenafil?

What Is Sildenafil? The Ultimate Guide to Generic Viagra for Erectile Dysfunction

Erectile dysfunction (ED) is very common, affecting millions of men around the world. It can be very distressing for the men who experience it.

But ED is treatable.

One of the most common treatments for ED is a class of medications called Phosphodiesterase 5 (​​PDE5) inhibitors. Of this class of medications, Viagra and its generic equivalent sildenafil are probably the most widely known.

So what exactly is sildenafil? Does it work? What are the side effects? And how can you get some? This article has answers to all of that and more.

What causes erectile dysfunction?

To get an erection, many different bodily systems have to work together. Sexual stimuli send signals through the brain and nerves, which release a chemical called nitric oxide in the penis. Nitric oxide relaxes muscles in the penis and allows blood vessels to dilate and get larger. The dilated blood vessels fill the penis with blood, making it grow rigid.

Because this process relies upon so many systems—psychological, neurological, and vascular—there are many things that can go wrong. That’s why there are many potential causes of ED. Some of the most common causes of erectile dysfunction include:

  • Psychological factors and mental health. Stress, anxiety, depression, and other psychological factors can impair the body’s ability to achieve and maintain an erection.
  • Lifestyle factors. Lifestyle factors can play a role in ED. Limited sleep, drug use, tobacco products, alcohol, and a sedentary lifestyle each can make ED more likely.
  • Medical conditions. Several medical conditions can contribute to ED, including cardiovascular disease, diabetes, hypertension, and high cholesterol.
  • Medications. Some medications are known to play a role in contributing to ED.
  • Physical injury. Damage to nerve tissue or to the pelvic area can impede erectile function.

What is sildenafil and what does it do?

Sildenafil and other PDE5 inhibiting medication work by helping blood vessels in the penis relax so they can fill with blood. They do that by increasing nitric oxide. More nitric oxide allows the muscles in the penis to relax and let more blood flow in.

PDE5 inhibitors work best for guys who are experiencing ED because of psychological factors or because of some issues with blood vessels in the penis not relaxing like they should. The result is that these medications:

  • Make it easier to get an erection
  • Reduce recovery time after orgasm

Note that sildenafil and other PDE5 inhibiting medication are not appropriate treatments for all forms of erectile dysfunction. For example, if you have nerve damage to the penis, they may not work. The right treatment depends on what’s causing the ED—that’s why you need a doctor to prescribe these treatments for you.

Also, note that sildenafil does not enhance sexual desire or libido. It does not cause an erection without sexual stimulation. It just makes it easier for an erection to occur when sexual stimuli is present.

Does sildenafil work?

Yes, there is a large body of research that has found that Viagra and sildenafil are effective treatments for erectile dysfunction. Studies find that it’s effective for between 77% and 84% of men.

However, Viagra and sildenafil are more effective for some people than for others. For example, while it has been found to lead to significant improvement of erectile function in all age groups, it appears to be more effective for younger men than older men. It also appears to be more effective for men with mild to moderate ED compared to those with severe ED.

Also, sildenafil may work differently if you take it with food. Food slows down absorption and can delay its effects.

Sildenafil safety and side effects

Is sildenafil safe?

Yes, research consistently finds that sildenafil is safe and well-tolerated by most men. However, there are some potential adverse effects that can occur from using sildenafil. Here are some of the adverse effects that sildenafil can cause, together with the percentage of participants in one systematic review that experienced those effects:

  • Flushing skin (12%)
  • Headache (11%)
  • Dyspepsia (5%)
  • Visual disturbance (3%)

Other potential side effects of sildenafil include:

  • Nosebleeds
  • Upset stomach
  • Trouble sleeping
  • Fever
  • An erection that lasts longer than normal
  • Respiratory infection
  • Nausea
  • Vomiting
  • Bronchitis
  • Sore throat
  • Runny nose
  • Low blood pressure
  • Priapism (unwanted, persistent erection)
  • Vision problems
  • Hearing problems
  • Heart problems

Remember to always follow the directions of your physician.

Important safety warnings for using sildenafil

Sildenafil isn’t right for everyone. Make sure that you answer all your doctor’s questions truthfully and completely so that they can determine if it’s safe for you.

Sildenafil interactions

Don’t take sildenafil if you take any nitrate medications, like nitroglycerine. Taking both can cause a dangerous drop in blood pressure. Similarly, do not consume grapefruits or grapefruit juice while taking sildenafil (or tadalafil): this can also cause a dangerous interaction.

Also be careful with other drugs that lower blood pressure, such as alpha-blockers or antifungal medications. If you’re using these medications, make sure you tell your doctor. They may provide an alternate ED treatment or recommend starting with a lower dose.

Can you drink alcohol while using sildenafil?

Sure, moderate alcohol consumption won’t hurt you. But heavy drinking can also lower blood pressure, which can be dangerous when you’re on sildenafil. So avoid heavy drinking while on ED medications.

Get assessed for other health conditions

Also, note that erectile dysfunction can sometimes signal more serious health issues. For example, ED can sometimes be caused by cardiovascular disease. So while it’s important to consult your doctor to treat your ED symptoms, it’s also important to seek treatment so your doctor can do further assessments to see if anything else is wrong.

Sildenafil alternatives

There are a number of treatment options for ED besides sildenafil. Here is how they compare.

Sildenafil vs. Viagra

Viagra is the brand name version of sildenafil—they have the same active ingredients. To be approved by Health Canada, the manufacturing company must show that generic versions are pharmaceutically equivalent to their brand-name counterparts. So don’t worry: generic sildenafil will have the same results as the brand name Viagra. It’s just as effective.

The only difference between the two is the price: sildenafil is much cheaper than Viagra.

Sildenafil vs. tadalafil (generic Cialis)

Both sildenafil and tadalafil have been shown to be effective at treating erectile dysfunction. Neither one is clearly more effective than the other. However, they do differ in how quickly they work and how long they work:

  • Sildenafil begins to work in about 60 minutes and lasts for about 4 hours (although its effects can linger for up to 36 hours). Food can delay its effects. Because it takes longer to work and is delayed by food, it’s not great for spontaneity. It requires some planning.
  • Tadalafil can be taken like sildenafil. It works in about 30 minutes and isn’t delayed by food, so it is slightly faster than sildenafil and requires less planning. It also lasts longer—up to 36 hours. We find that men prefer tadalafil over sildenafil because it’s faster-acting and longer-lasting.
  • Tadalafil can also be taken in smaller doses every day. Daily tadalafil requires the least planning and offers more opportunities for spontaneous sex.

Read more: What is Tadalafil? Your Complete Guide to Generic Cialis for ED

Read more: What is Daily Tadalafil? Your complete guide to the once-a-day treatment for ED

Do you need a prescription to buy sildenafil in Canada?

Yes, you need a prescription to buy sildenafil and tadalafil in Canada.

But that doesn't mean you have to go into the doctor’s office. You can start your online visit and be evaluated by a medical professional right now. If you’re approved, you’ll get a prescription and we’ll ship the medication to your home.

Where to buy sildenafil in Canada?

Once you have a prescription, you can buy sildenafil in pharmacies or from online ED clinics like Essential Clinic.

Some online sites try to sell viagra and sildenafil without a prescription. These are not only illegal but also dangerous because the drugs are often counterfeit. Knockoff medications often contain harmful chemicals that can do some serious damage to your health. Don’t take the risk.

It’s much better to get a convenient prescription online and buy your ED medications from a reputable source.

Get treatment for erectile dysfunction

Erectile dysfunction can be distressing and embarrassing. Many men do not seek treatment because they feel awkward talking about it.

Online consultations can help. Our experts are professionals and see patients experiencing erectile dysfunction every day, so they know exactly how common it is. And we make sure that we ship all ED medication in discreet packaging, so you don’t have to feel embarrassed picking up your meds.

We make the process as comfortable as possible.

ED doesn’t have to mean the end of your sex life. Start your online visit to get it sorted out today.


Ayta, I. A., McKinlay, J. B., & Krane, R. J. (1999). The likely worldwide increase in erectile dysfunction between 1995 and 2025 and some possible policy consequences. BJU International, 84(1), 50-56.

Doggrell, S. A. (2005). Comparison of clinical trials with sildenafil, vardenafil and tadalafil in erectile dysfunction. Expert Opinion on Pharmacotherapy, 6(1), 75-84.

Fink, H. A., Mac Donald, R., Rutks, I. R., Nelson, D. B., & Wilt, T. J. (2002). Sildenafil for male erectile dysfunction: a systematic review and meta-analysis. Archives of Internal Medicine, 162(12), 1349-1360.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.