Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 4/21/2021
Tadalafil, the active ingredient in Cialis®, is a prescription medication that’s used to treat erectile dysfunction (ED). You can buy tadalafil online along with other FDA-approved ED medications, following a consultation with a healthcare provider who will determine if a prescription is appropriate.
As a type of PDE5 inhibitor, tadalafil treats erectile dysfunction by increasing blood flow to your penis, making it easier for you to get an erection when you feel sexually aroused.
Like sildenafil (the active ingredient in Viagra®), avanafil (Stendra®) and other ED medications, tadalafil is available in several dosages. It’s important to choose the right dosage for your needs to treat ED without causing side effects or complications.
Below, we’ve talked about how tadalafil works to treat ED, as well as the most common tadalafil dosages. We’ve also explained how you can get the best results if you’re prescribed tadalafil to treat erectile dysfunction.
Tadalafil is a widely-used medication (What is tadalafil used for?). It’s mostly prescribed to treat erectile dysfunction, but is also used to treat benign prostatic hyperplasia (BPH).
Compared to other ED medications, tadalafil is very long lasting. On average, a typical dose of tadalafil can improve erectile function for up to 36 hours.
Tadalafil is available in several dosages. As a treatment for ED, it’s typically prescribed at a dosage of 10mg for use as needed, which may be adjusted to 20mg or 5mg based on your response to the medication.
For once-daily use, tadalafil is prescribed at a lower dosage of either 2.5mg or 5mg per day.
Like with other ED medications, there’s no “best” dosage of tadalafil for everyone. Your healthcare provider will work with you to choose the best dosage based on your needs, response to the medication and other factors.
Tadalafil works by inhibiting the effects of cGMP-specific phosphodiesterase type 5, or PDE5 — an enzyme that’s found in the smooth muscle cells of blood vessels.
PDE5 plays a major role in regulating the flow of blood to certain parts of your body, including the erectile tissue of your penis. By inhibiting the effects of PDE5, tadalafil makes it easier for blood to flow to your penis and produce an erection.
Contrary to popular belief, tadalafil and other PDE5 inhibitors won’t cause you to randomly get erections. Instead, they just increase blood flow, meaning you’ll only get an erection when you feel sexually aroused.
Our guide to PDE5 inhibitors provides more information about how tadalafil, sildenafil and other medications for erectile dysfunction work.
Tadalafil is available in several different dosages, from a minimum dosage of 2.5mg all the way up to a maximum dose of 20mg per tablet. For optimal results, you should take tadalafil at least 30 minutes before you and your partner plan to have sex.
As a long-lasting ED medication, tadalafil is only recommended for use one time per day. Used at a typical as-needed dosage, tadalafil remains effective for up to 36 hours.
10mg is a typical starting dosage of tadalafil. Tadalafil is typically prescribed at this dosage for use as-needed before sex.
If you have mild to moderate ED, or if you’re just starting with tadalafil, your healthcare provider may prescribe the medication at this dosage. Research shows that most men with ED who use tadalafil at this dosage are able to have sex successfully.
If you don’t notice any improvements from a 10mg dosage, or don’t experience a large enough improvement to have satisfactory sex, your healthcare provider may prescribe a stronger 20mg dosage of tadalafil.
At this dosage, tadalafil is more effective at improving erectile function and helping men with ED have sex successfully. Research shows that a dosage of 20mg is particularly effective for men with severe erectile dysfunction.
This is the highest recommended dosage of tadalafil. Clinical trials show that side effects from tadalafil are slightly more common at this dosage than at a lower dosage of 10mg, although the difference is relatively small.
If you only have mild erectile dysfunction, or if you develop side effects from using tadalafil at a higher dosage, your healthcare provider may prescribe tadalafil at a dosage of 5mg.
This is the lowest as-needed tadalafil dosage that’s currently in use. Although it’s slightly less effective than the 10mg and 20mg dosages at treating and preventing ED, it’s also less likely to cause certain side effects.
Tadalafil is available for use as-needed and for once-daily use. As a once-daily medication, it’s available at a dosage of 2.5mg or 5mg.
Using tadalafil daily offers several advantages, as we’ve explained in our full guide to daily-use Cialis. However, it can also mean that some side effects, such as indigestion and flushing, may become more frequent.
When used daily, tadalafil should be taken at approximately the same time each day in order to maintain a stable concentration in your body.
Once you and your healthcare provider have worked out the correct dosage for you, tadalafil is usually effective at improving your erections and enhancing your sexual performance.
To get the best results from tadalafil, try to:
Take tadalafil at least 30 minutes before you have sex. Tadalafil usually reaches its peak blood concentration between 30 minutes and six hours.
If you’re prescribed tadalafil for use as-needed, you’ll get the best results by taking it at least 30 minutes before you and your partner plan to have sex. If you don’t notice any improvement, try taking tadalafil approximately one hour before you have sex.
Limit your alcohol consumption. Taking tadalafil(Cialis) with alcohol may increase your risk of developing side effects, including reduced blood pressure. Alcohol may also affect your sexual performance and ability to maintain an erection during sex.
While it’s alright to drink a small amount of alcohol while using tadalafil, it’s best to avoid drinking large amounts of alcohol while using this medication.
Combine tadalafil with a healthy lifestyle. Your cardiovascular health plays a key role in your erectile function and sexual performance, meaning medications such as tadalafil work best if you live a healthy lifestyle.
Our guide to naturally protecting your erections shares actionable, science-based tactics that you can use to improve your sexual health and get better results from tadalafil.
The maximum dosage of tadalafil is 20mg, used as needed. If you’re prescribed tadalafil at this dosage, it’s important to follow your healthcare provider’s instructions and take your medication no more than once per day.
Taking 40mg of tadalafil (two 20mg tablets) is not recommended. This dosage of tadalafil is far higher than the typical recommended dose. Taking tadalafil at this dosage could increase your risk of developing side effects, including potentially harmful side effects.
If you don’t experience improvements from tadalafil at a dosage of 10mg or 20mg, talk to your healthcare provider.
Tadalafil is the longest-lasting medication for erectile dysfunction. A single dose of tadalafil may provide relief from ED for up to 36 hours, or approximately one and a half days.
The half-life of tadalafil is approximately 17.5 hours, meaning a 20mg dosage takes around four days to exit your system. In elderly men, tadalafil has a slightly longer half life of approximately 21.6 hours and may take four to five days to completely exit the body.
Tadalafil is one of four medications for ED, along with sildenafil (Viagra), vardenafil (Levitra) and avanafil (Stendra).
If you’re one of the tens of millions of men in the United States affected by ED, medications like tadalafil can improve your erections and make it easier to have satisfying sex.
We offer tadalafil and other FDA-approved ED medications online, following a consultation with a healthcare provider who will determine if a prescription is appropriate.
You can also learn more about treating ED and improving your sexual performance in our guide to the most common erectile dysfunction treatments and drugs.