Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 2/25/2021
Erectile dysfunction medications like sildenafil (Viagra®, generic Viagra), tadalafil (Cialis®), vardenafil (Levitra®) and avanafil (Stendra®) are some of the most widely used prescription drugs available today.
They’re also some of the most well understood, with a huge number of studies observing direct effects, side effects, their average onset of action, half-life and other important factors that affect how each medication affects your body.
Below, we’ve covered what you should expect from erectile dysfunction medication, from how long you should expect to wait before the medication takes effect to the side effects you could experience as a result of the medication.
We’ve also provided data to help you directly compare the four ED medications currently on the market, from well-known options such as sildenafil (Viagra) to newer erectile dysfunction drugs such as avanafil (Stendra).
This article is for informational purposes only and you should talk to your primary care provider before starting an ED treatment program.
Most erectile dysfunction drugs take 30 to 60 minutes to start working. The fastest-acting ED medication is avanafil (Stendra), which can start producing noticeable effects in 15 minutes if you use a moderate to high dose of the medication.
Sildenafil, or Viagra, takes approximately one hour to start working and should be taken about 60 minutes before you plan to have sex.
Most of the time, a typical dose of sildenafil will begin to produce a noticeable effect between 30 and 60 minutes after it's consumed orally.
Tadalafil, or Cialis, generally takes between 30 and 60 minutes to start working, but for some men it can take up to 2 hours or as little as 15 minutes to start working.
Finally, vardenafil, or Levitra, take action in about the same amount of time as sildenafil. Most manufacturers of vardenafil recommend that you take the drug about 60 minutes before sexual activity in order to give it time to begin working.
Regardless of the specific medication you use, it’s best to take your ED medication about one hour before you plan to have sex. Prepare ahead of time and you’ll experience the medication’s full effects when you and your partner become intimate.
As always, if your healthcare provider provides a specific recommendation for when to take your medication, it’s important to follow their advice.
All of the four ED medications listed above can be used with or without food. Most ED drug manufacturers recommend taking sildenafil, tadalafil, vardenafil or avanafil with a glass of water on a relatively empty stomach (or after a normal-sized meal).
A drug’s half-life is the amount of time required for the concentration of the medication in your body to fall to half of its peak.
For example, a normal 50mg dose of sildenafil (Viagra) will be reduced to a potency of approximately 25mg after one half-life has passed.
The half-life of a medication determines how long it will remain active in the body. Generally, ED drugs still provide some effects after one half-life and gradually become less effective as they’re eliminated from the body and excreted.
After two to three half-lives have passed, the medication will be completely ineffective and won’t provide any noticeable effects.
Below, we’ve listed both the half-lives and duration of action for all four of the most common ED drugs:
Sildenafil, or Viagra, has a half-life of four to five hours and remains active in the body as an effective erectile dysfunction treatment for 3 to 5 hours after it’s consumed.
Tadalafil, or Cialis, has a half-life of 17.5 hours and remains active in the body as an effective erectile dysfunction treatment for up to 36 hours after it’s consumed.
Vardenafil, or Levitra, has a half-life of four to five hours and remains active in the body for up to six hours after it’s consumed.
Avanafil, or Stendra, has a half-life of three to five hours and remains active in the body for up to six hours after it’s consumed. This gives it a similar period of effect than vardenafil and a slightly longer half-life than sildenafil.
As you can see, tadalafil is by far the longest-lasting of the four ED medications currently on the market. All men react differently to each medication. It is important to speak openly with your healthcare provider to provide the best medication for your ED.
Because of this, tadalafil is usually the preferred option for men who want to treat ED for several days at once without needing to take several tablets of their ED medication. Shorter-acting drugs, such as sildenafil, vardenafil and avanafil, are generally preferred for incidental use.
Tadalafil also has the added benefit of treating benign prostatic hyperplasia (BPH). Of course, using tadalafil to treat either erectile dysfunction or BPH should always be discussed with your primary care provider.
Because most ED drugs work similarly, they also have similar side effects. The side effects of ED drugs typically occur while the medications are active in the body, although in some cases it’s possible for the side effects of ED medication to last for slightly longer than the drug itself.
This means that if you’re prone to side effects from ED drugs, you may notice them lasting for longer if you use a medication such as tadalafil, which has a very long half life.
Commonly reported side effects of ED drugs are:
Mild headaches, which are associated with all ED drugs.
Dizziness. The dizziness from ED medication is typically not severe, but it can potentially lead to discomfort and fainting in people with underlying health conditions.
Muscle aches or back pain
Nasal congestion, or a stuffy nose.
Facial flush, which can range from mild facial redness to bright red skin that looks like it’s affected by a rash, generally experienced more with sildenafil.
Vision issues, including temporary blurry vision and blue-tinted vision.
Digestive issues, ranging from diarrhea to indigestion and bloating. These are usually temporary and can be made worse by consuming alcohol, caffeine, carbonated drinks and dairy products.
As a second-generation ED medication, avanafil is more selective in the tissue it targets. This means it’s less likely than older medications to cause certain side effects, such as changes to vision and certain cardiovascular effects.
Some of the side effects above, such as headaches and dizziness, are particularly important to pay attention to if you have cardiovascular health conditions.
All of the ED medications currently available can cause a mild reduction in your blood pressure levels. This is caused by their effects on smooth muscle tissue and blood flow. This reduction is mild and does not cause any dangerous side effects in healthy men.
However, if you use nitrates or certain other medications to treat hypertension, the reduction in blood pressure caused by ED medications can be dangerous.
If you use any nitrates, you must not use sildenafil, tadalafil, vardenafil, avanafil or other similar medications.
Our guide to ED medication for men with heart disease explains these interactions and effects in more detail, as well as what you can do to safely treat erectile dysfunction if you take medication to treat an existing cardiovascular condition.
The cost of treating erectile dysfunction using commonly prescribed medications like sildenafil, tadalafil, vardenafil and avanafil can vary depending on a variety of factors.
The first factor is the dosage you use. Most ED medications come in a range of doses, meaning that an effective dose for one person might not be equal to an effective dose for another person. Your primary care provider can help determine what dose you should use.
The second factor is the specific medication you use. Sildenafil, tadalafil, vardenafil and avanafil are all different medications available at different prices.
The third factor is the amount of medication that you use. If you use ED medication every day, the cost can quickly add up; if you take it once or twice per week, the total cost per year will be far lower.
The fourth factor is your insurance coverage. While some insurance policies do not cover the cost of ED medication, others do, making the cost of treating erectile dysfunction far lower.
Finally, a significant cost factor is the brand of medication you choose. Many ED drugs are sold as branded medications such as Viagra, Cialis and Levitra, but are also available at much more affordable prices as generic medications.
Would you like to learn more about ED medication? Our guide to the best fast-acting male enhancement pills will provide more information on available fast-acting ED pills, and our guide to the most common erectile dysfunction treatments covers sildenafil, tadalafil, vardenafil and avanafil in more detail, letting you get a complete understanding of the most widely used ED medications on the market today. You can also check out our article on Cialis vs Viagra to understand the difference between the two ed drugs.
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