Tadalafil 20 mg: how long does it last, uses, and more

You may know that tadalafil (brand names: Cialis, and others), is a medication commonly prescribed for erectile dysfunction (ED). And if you’ve ever been prescribed it, you probably know it comes in various strengths from 2.5 mg to 20 mg. 

It’s easy to believe that higher doses are always more effective, but that isn’t always the case. In this article, we’ll explore how long it takes tadalafil 20 mg to start working, side effects, and other key details.

Typically, Cialis (tadalafil) 20 mg can be used as needed to treat ED. 

Tadalafil belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors. Other popular PDE5 inhibitors are sildenafil (Viagra) and vardenafil. These drugs work in part by relaxing blood vessels and increasing blood flow to certain areas of the body, including to the penis.

Other than treating ED, tadalafil is also used to manage other conditions, but the most common use for tadalafil 20 mg tablet is erectile dysfunction. In fact, it’s the maximum dose used for erectile dysfunction.

Tadalafil works by blocking the PDE5 enzyme. This triggers changes in blood vessels that allow increased blood flow to the penis, prostate, or lungs, depending on the condition being treated.

Tadalafil 20 mg lasts for up to 36 hours after you take it. The maximum frequency is typically one dose per day, but some people take one dose every 2 or 3 days at the most. 

Keep in mind that individual results can vary with tadalafil due to metabolism, genetics, and other factors. Certain drug interactions may also affect how long tadalafil lasts and could make tadalafil less effective by reducing its amount in the body.

In contrast, some other medications and foods could increase the levels of tadalafil in your body, possibly raising the risk or severity of side effects. Examples include the antibiotic erythromycin (Ery-Tab), the antifungal itraconazole (Sporanox), and grapefruit juice. 

Be sure to discuss all of your current medications and supplements with your healthcare provider and pharmacy so they can help identify any potential interactions.

Common side effects of tadalafil 20 mg include headache, indigestion, back pain, muscle aches, flushing, and stuffy or runny nose. Dizziness may also occur. These side effects are usually mild and tend to go away on their own within a few hours to a couple of days.

Serious side effects of tadalafil, such as severe allergic reactions, vision or hearing problems, and priapism (a prolonged erection that doesn’t go away for 4+ hours and requires emergency medical care), are rare but possible. 

In addition to the interactions discussed above, tadalafil can cause a life-threatening drop in blood pressure if combined with nitrates such as nitroglycerin. Nitrates are a class of drugs used to treat angina (a type of chest pain) in people with heart disease. 

If you’ve taken any nitroglycerin or other nitrates within the last two days, you should not take tadalafil. And most guidance suggests not taking nitrates for at least 48 hours after taking tadalafil—but call your healthcare provider right away for personalized medical advice if you’re unsure what to do.

Low blood pressure can also happen if tadalafil is used alongside alpha blockers, such as doxazosin, a medication for high blood pressure. Consult a healthcare professional if you have questions or concerns about possible side effects or interactions.

Tadalafil 20 mg is usually taken by mouth at least 30 to 60 minutes before sex. The 20 mg dose is meant to be taken "on demand," or as needed, up to once a day. It's important to swallow the tablet whole and not split it in half, according to the labeling for Cialis.

According to single-dose studies of tadalafil 20 mg, it takes anywhere from 30 minutes to 6 hours for the medication to reach peak levels in the blood. Note this doesn’t mean you’ll automatically get an erection. As with other PDE5 inhibitors, sexual stimulation is a necessary step in getting and keeping an erection after you take tadalafil.

Although tadalafil can start to have an effect as quickly as 15 minutes after taking it, most men do not experience results that early. The average time to kick in is one hour and it usually takes around 2 hours to reach its maximum benefits. 

It's important not to expect immediate results, as this could result in unnecessary stress or sexual performance anxiety. Patience is key, and giving the medication enough time to work helps set you up for the best results. Since a dose of tadalafil 20 mg lasts up to 36 hours, you have plenty of time to work with.  

You can take tadalafil with or without food. So, no need to worry about meal timing or delayed effects. But how about alcohol? While it may not directly interact, it may be best to limit how much alcohol you drink while taking tadalafil. Drinking too much alcohol can make tadalafil’s side effects, such as headache or dizziness, worse than usual. Heavy alcohol consumption can also negatively affect erections.  

The retail price for generic tadalafil 20 mg is around $503 for ten tablets. But most people don’t pay the full retail price.

Your cost for tadalafil 20 mg can vary depending on the pharmacy you use and whether you have insurance coverage or discount offers. Many men choose to refill only a small number of tablets at a time to make the cost more manageable. 

Tadalafil 20 mg is the highest dose for ED. People don’t typically start with this dose because higher doses of tadalafil are more likely to cause headache and indigestion as side effects. 

The FDA has approved several versions of tadalafil, which come in different forms and strengths. The most popular option is the generic version of Cialis, which is approved to treat ED and BPH. It comes as an oral tablet in the following strengths: 2.5 mg, 5 mg, 10 mg, and 20 mg.

While not FDA-approved, other treatment options are available that offer the benefits of tadalafil in gummy form. One example is Ro Daily Rise Gummies, a fruit-flavored once-daily gummy that provides 7 mg of tadalafil. 

As mentioned, there are two dosage options for treating ED with tadalafil: once daily and as needed. 

On demand for ED. Typically, the starting dose of tadalafil for as-needed use is 10 mg taken at least 30 minutes before sex. Its effects last up to 36 hours—a day and a half. If 10 mg isn’t effective enough, it may be increased to 20 mg. On the other hand, if 10 mg is effective but causes bothersome side effects, it may be decreased to 5 mg. It’s common to have some trial-and-error; be sure to communicate with your healthcare provider before making dose changes. They may adjust your regimen until you find the amount that’s right for you.

Once daily for ED. Alternatively, lower doses of tadalafil (2.5 mg or 5 mg) may be taken once daily. The once-daily dosing option may be preferred for men who want to be ready for sexual activity at any time without needing to plan ahead. For this regimen, tadalafil may be taken at any time of day, without regard to sexual activity.

Your healthcare provider will consider several factors when deciding if tadalafil 20 mg is right for you. If a lower dose isn't effective, they might increase it to 20 mg. However, if you're experiencing side effects like headaches or back pain, you may benefit from a lower dose (10 mg or 5 mg). 

If tadalafil isn't working well despite dosage adjustments, your provider might suggest trying a different PDE5 inhibitor, like sildenafil or vardenafil. These medications are shorter-acting, which might make them a better choice for ED than longer-acting tadalafil in some situations.

Ultimately, the goal is to find the treatment that works best for your needs while minimizing any negative effects. Connect with a healthcare provider to see if tadalafil or another ED medication is right for you.

---

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Editorial Guidelines | Medical Review Process

Current version

September 12, 2024

Written by

Patricia Weiser, PharmD

Fact checked by

Raagini Yedidi, MD

---

About the medical reviewer

Raagini Yedidi, MD

Raagini Yedidi, MD, is an internal medicine resident and medical reviewer for Ro.