Medically reviewed by Angela Sheddan, DNP, FNP-BC
Written by Our Editorial Team
Last updated 4/29/2021
Experiencing erection problems? Looking for ED cures? Whether you’re 25 or 60+ years old, you’re certainly not alone.
About 30 million American men are affected by erectile dysfunction or ED. Interestingly, while ED is often thought of as a condition that affects middle-aged and older men, around a quarter of all men under 40 experience ED on a regular basis.
Luckily, a range of erectile dysfunction medications are available to treat the effects of ED and help you develop and maintain an erection without any problems.
Three of the most popular erectile dysfunction drugs on the market are sildenafil (active ingredient in Viagra®, generic Viagra), vardenafil (Levitra®) and tadalafil (Cialis). These are all first-generation treatments for ED that were introduced in the 1990s and early 2000s.
There’s also avanafil, or Stendra® -- part of a new generation of erectile dysfunction medications that treat erectile dysfunction with a lower rate of side effects than the first-generation drugs.
While there’s no “perfect” med for ED, all four erectile dysfunction treatments provide the same key benefit -- better blood flow to the penis and fewer difficulties developing an erection.
However, they also have some differences, ranging from shorter or longer half-lives to different side effect profiles.
And before we get started, we want to say that there’s no “best ED treatment.” Your missions shouldn’t be finding the best ED treatment — it should be finding the best ED treatment for you, but, no, vapor rub on penis does not work.
Below, we’ve compared sildenafil (active ingredient in Viagra), vardenafil (active ingredient in Levitra), tadalafil (active ingredient in Cialis) and avanafil (active ingredient in Stendra) to give you a more complete understanding of the most popular medications used today to treat erectile dysfunction.
Sildenafil, the active ingredient in Viagra, is one of the most common and widely used treatments for ED available today.
Originally developed as a treatment for heart health issues, sildenafil was approved as an ED drug in the late 1990s.
Since its approval for ED in 1998, Viagra has become one of the most popularly prescribed medications for ED in the world.
Sildenafil works by increasing blood flow to the spongy erectile tissue of the penis, making it easier for you to achieve an erection. It usually works within 30 to 60 minutes of consumption and lasts for three to five hours, depending on the person.
You can take sildenafil with or without food, although taking it after a big meal with a lot of fat might slow down your body’s absorption of the drug.
The potential side effects of sildenafil are the same as most other ED drugs -- headaches, nasal obstruction, flushed skin and heartburn.
Sildenafil can also potentially lead to more serious side effects, particularly in people with heart conditions or those who take other prescription erection medication.
More specifically, it can interact with certain nitrates used to treat hypertension and cause issues related to low blood pressure.
Because of this, it’s important to talk to a qualified healthcare professional before you consider using sildenafil or any other prescription med for ED.
Sildenafil comes in a variety of doses, ranging from 20mg to 100mg. Higher sildenafil doses are typically used to treat more serious cases of erectile dysfunction for people that don’t respond to the 20 or 50mg tablets.
All in all, sildenafil is popular for a reason -- it works. For most men, sildenafil makes it easier to develop and maintain an erection and acts as a reliable, safe medicine for erectile dysfunction.
Developed in the 1990s and approved by the FDA in 2003, tadalafil is a longer-lasting ED drug that provides similar effects to sildenafil.
Tadalafil is better known by the brand name Cialis. With a 17.5 hour half life, tadalafil remains active for up to 36 hours after it's taken, making it the longest-acting of the erectile dysfunction drugs available today.
To put this in perspective, a typical dose of sildenafil lasts for about three to five hours. To get the same results as you’d get from one dose of tadalafil (Cialis), you’d need to take multiple sildenafil tablets over the course of two days.
Tadalafil comes in tablet form and belongs to a class of drugs called phosphodiesterase 5 (PDE5) inhibitors.
When you become sexually aroused by something, your brain sends signals to the rest of your body — including your penis. When those signals reach the corpora cavernosa (spongy tissue that run through the shaft of your penis), they release neurotransmitters that result in the production of nitric oxide.
From there, in the penis, that nitric oxide helps stimulate the formation of cGMP in the smooth muscle of the penis, which causes those muscles to relax and allow for blood to flow into the penis, where it’s trapped to create an erection.
PDE5, however, degrades cGMP over time, which is a primary physiological reason for erectile dysfunction. PDE5 inhibitors like tadalafil interrupt the release of PDE5, which means the cGMP keeping your smooth muscle relaxed and ready for blood flow gets to do its job without issue.
Tadalafil may take up to two hours before it’s fully effective, which means you should plan ahead. Like sildenafil, it can be taken with or without food.
The side effects of tadalafil are similar to sildenafil, with headache, stuffy nose, heartburn and facial flushing the most common. Tadalafil can also cause muscle aches and back pain, which are usually a result of the drug’s vasodilation effect.
Like sildenafil, tadalafil can interact with some medications used to treat hypertension and other cardiovascular conditions. Because of this, you should let your healthcare provider know if you use any other erection medication before considering tadalafil.
For most people, the biggest advantage of tadalafil over sildenafil is its longer half life. A single dose of tadalafil usually lasts for most of a weekend, eliminating the need to take the pill directly before sexual activity.
Compared to sildenafil, the typical dosage of tadalafil is far lower. The normal starting dose is 10mg taken one hour before sexual activity, with doses of 5mg and 20mg also used depending on the way people respond to treatment.
Overall, tadalafil is a good option for men who dislike taking a pill immediately before sex and want a long-lasting erectile dysfunction pill suitable for entire days and weekends.
Vardenafil is another ED drug that works similarly to sildenafil and tadalafil. Like tadalafil, it was introduced in the early 2000s as an alternative to sildenafil with a slightly longer half life, making it a longer-lasting ED treatment.
The most common brand name for vardenafil is Levitra. Like sildenafil and tadalafil, vardenafil is available as a prescription medication in most countries, meaning you’ll need to talk to a healthcare professional before you can use it.
Vardenafil is another PDE5 inhibitor, which means that, like tadalafil, it inhibits the production of the PDE5 enzyme responsible for disrupting and degrading cGMP enzyme during sexual activity.
Compared to sildenafil, which lasts for three to five hours, vardenafil typically lasts for at least five hours, but studies have shown that it’s effective for up to seven hours — after which it remains active in the body but doesn’t provide as strong an effect.
The side effects of vardenafil are similar to other ED medications. The most commonly reported side effects include facial flushing, headaches, stuffy nose and heartburn. These typically pass as the medication’s concentration in your bloodstream decreases over several hours.
Like other ED drugs, it’s also linked to more serious side effects in people with pre-existing heart conditions who use other medications. Specifically, vardenafil can interact with nitrates similarly to sildenafil, tadalafil and other medications used to treat ED.
Because of this, it’s important to talk to a healthcare professional before considering vardenafil or any other ED treatment.
A normal dose of vardenafil takes action in about one hour. Like sildenafil and tadalafil, you can take vardenafil with or without food.
On a per-milligram basis, vardenafil is significantly stronger than sildenafil and is usually used at a lower dose. The normal starting dose of vardenafil is 10mg, with tablets available in 2.5, 5, 10 and 20mg doses.
On the whole, vardenafil is suitable for men who want something longer-lasting than sildenafil, but don’t need the 36+ hours of ED treatment that tadalafil provides.
Avanafil (active ingredient in Stendra) is a new, second-generation erectile dysfunction drug. Just like sildenafil, vardenafil and tadalafil, it’s a PDE5 inhibitor, meaning it improves blood flow to the penis and makes it easier to get an erection.
Developed throughout the 2000s, avanafil was approved by the FDA in April of 2012. In the US, it’s sold under the brand name Stendra. It’s also sold in some non-US markets under the brand name Spedra.
Though it’s the new kid on the block of PDE5 inhibitors, avanafil is still just that — a PDE5 inhibitor. That means it’s mechanism of action is the same as all the other PDE5 inhibitors.
What makes it unique, however, is that it inhibits PDE5 faster than other medications in its class, which means the cGMP in the smooth muscle of your penis has more time to relax, allow blood to flow in and create an erection.
It also has a slightly longer terminal half-life than sildenafil, which means it may last a little longer, too.
All told, there’s research out there to suggest avanafil starts having an effect on erection quality in just 15 minutes. On average, avanafil works for up to six hours as a medicine for erectile dysfunction, meaning it lasts for slightly longer than sildenafil.
Unlike sildenafil and other first-generation erectile dysfunction treatments, avanafil is much more selective in the tissue it targets. This means it’s less likely to produce certain effects than older ED medications.
The side effects of avanafil are similar to those of other ED medications, with headache, nasal congestion and facial flushing the most commonly reported.
Because it specifically targets the PDE-5 isoenzyme, avanafil has a lower risk of causing side effects than other ED drugs.
Like other ED medications, avanafil can interact with some medications used to treat high blood pressure and other cardiovascular conditions, including nitrates.
Avanafil is available in several dosages, ranging from 50 to 200mg. The typical starting Avanafil dose is 100mg for use 30 minutes before sexual activity, although doses of 200mg and 50mg can also be used to treat severe and mild cases of erectile dysfunction, respectively.
Overall, avanafil is an appealing option for men who want a newer ED medication with similar effects to Viagra and a lower risk of causing side effects.
To learn more, check out our article on the latest treatments for erectile dysfunction.
All four of the ED treatments covered above -- sildenafil, tadalafil, vardenafil and avanafil -- are widely used and scientifically proven to treat erectile dysfunction, meaning you should get good results regardless of which medication you use.
But remember: these drugs are ED treatments — not ED cures.
In general, the biggest difference between these treatments is the average amount of time each medication lasts.
Some, such as sildenafil, are fairly short-acting, while others, such as tadalafil, are specifically designed to provide relief from ED that lasts for several days.
Ultimately, the best ED drug for you depends on your needs. If you’re interested in treating ED but don’t know which drug is the best choice, you should speak to an experienced ED doctor to learn more about the potential benefits and side effects of each treatment option.