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How Does Cialis Work and What to Do If It Doesn’t

Kristin Hall, FNP

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 7/5/2022

Cialis® is one of several medications used to treat erectile dysfunction (ED). Thanks to its long half-life, it can provide relief from erectile dysfunction that lasts for 36 hours.

Like Viagra®, Stendra® and Levitra®, Cialis is highly effective as a treatment for ED. Studies of tadalafil, the active ingredient in Cialis, show that it improves erections and enhances sexual performance even at a relatively low dose. 

However, no medication has a 100 percent success rate, and Cialis is no exception. Even after you take Cialis, you could still experience some symptoms of ED. Below, we’ve explained some reasons why this can happen, as well as some things you can do if Cialis doesn’t work for you. 

How Does Cialis Work?

Tadalafil, the active ingredient in Cialis, works the same way as the sildenafil used in Viagra, the avanafil used in Stendra or the vardenafil used in Levitra. They’re all categorized as PDE5 inhibitors.

After you take Cialis, your body absorbs the tadalafil inside the tablet. Tadalafil will increase blood flow to the blood vessels in the erectile tissue of your penis by inhibiting the PDE5 enzyme. This makes it easier for blood to flow into your penis when you’re ready for sexual activity, giving you an erection.

However, this doesn’t always happen.

According to Harvard Men's Health Watch, the active ingredients used in Cialis, Viagra, Stendra and Levitra are only fully effective around 70 percent of the time in the healthy men that take them, meaning that many men still have erection issues even with the use of medication.

Factors That Can Affect How Cialis Works

Sometimes, symptoms associated with ED can persist because the medication wasn’t used properly. In other cases, other health issues can affect the effectiveness of Cialis. Below, we’ve listed several of the most common reasons why Cialis might not work for you:

You’re Not Using Cialis Correctly

Cialis is designed to be used under specific conditions for maximum effectiveness. While you should always take Cialis exactly as your healthcare provider tells you to, it is generally recommended that for optimal results, you should:

  • Take Cialis at least one hour before sex. How long does it take for Cialis to work? Cialis can take up to one hour to start fully working inside your body, according to an article published in the journal, Patient Preference and Adherence. Try to take your Cialis tablet at least one hour before sex for optimal results.

    Since Cialis is a long-lasting medication, you can take it several hours before sex without having to worry about its effects wearing off. According to a randomized controlled trial published in The Journal of Sexual Medicine, unlike Viagra®, there’s no need for you to take Cialis on an empty stomach.

  • Avoid drinking alcohol or taking recreational drugs. Not only can alcohol make Cialis and other medications less effective, but it can also affect your blood flow. This side effect of mixing Cialis with alcohol makes it harder to get an erection even with the help of medication.

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You’re Not Using the Right Dose of Cialis

Cialis comes in several dosages: 2.5 mg, 5 mg, 10 mg and 20 mg. Most of the time, the 10mg and 20mg dosages are used to treat erectile dysfunction, although the lower 5mg dosage is also occasionally used to treat cases of mild to moderate ED, according to an article published in the journal, BMC Urology

Lower doses of Cialis, like 2.5 mg and 5 mg tablets, tend to be used to treat mild ED and medical conditions such as benign prostatic hyperplasia (BPH), according to a clinical trial published in The Journal of Sexual Medicine

If you’re prescribed a lower dosage of Cialis and you find that it’s not fully effective (for example, you notice some improvements but still have difficulty maintaining an erection), it’s a good idea to discuss this with your healthcare provider to see if switching you to a higher dose is appropriate.

You’re Experiencing Performance Anxiety

ED can be caused by sexual performance anxiety — a feeling of nervousness and anxiety before and during sex. If you’re affected by sexual performance anxiety, it’s quite normal to feel worried about Cialis’ effectiveness the first few times you use it.

This nervousness can result in worse ED than normal even after sexual stimulation, meaning that Cialis might not be totally effective as a treatment. 

If you find that Cialis doesn’t work the first time you use it at a normal dosage, you may want to stick with it before you throw in the towel on this specific medication. Wait until you feel relaxed, confident and in the right mood so that you can judge Cialis’s performance fairly. 

Your ED is Caused by a Psychological Condition

Cialis is designed for the treatment of erectile dysfunction’s physical causes, such as poor blood flow to the erectile tissue of your penis. However, it’s not a psychiatric medication and isn’t designed to be a treatment for some psychological causes of ED.

According to an article published in the journal, Health Psychology Open, erectile dysfunction can be associated with anxiety, stress and depression. If you have a mental illness or other condition that affects your sexual performance, Cialis (as well as other ED drugs like Viagra, Stendra or Levitra) might not be a completely effective treatment. 

If you think this is the cause of your ED, it’s important to talk to your healthcare provider. Sexual performance issues caused by mental illnesses can often be treated through therapy, medications and other treatment options. 

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Your ED is Caused by a Physical Health Condition

Erectile dysfunction is often caused by a physical health condition, such as pulmonary arterial hypertension (high blood pressure), diabetes, Peyronie's disease or nerve damage.

Tadalafil, the active ingredient in Cialis, works by increasing blood flow to the erectile tissue of your penis. This makes it effective for most cases of ED. However, certain physical conditions can cause ED that isn’t completely treated by Cialis.

According to an article published in the Arab Journal of Urology, beyond the cardiovascular causes of ED, issues such as low testosterone can affect both your sexual performance and your general level of interest in sex. Because Cialis isn’t a hormonal medication, it might not be completely effective at treating ED if this is the underlying cause. 

If you’re concerned that your sexual performance issues are caused by an underlying physical health condition, talk to your healthcare provider. By treating the underlying condition, you can often improve your sexual performance with or without the use of medications such as Cialis. 

Porn is Affecting Your Sexual Performance

If you frequently watch porn, it could negatively affect your sexual performance, causing you to face difficulties getting and maintaining an erection. 

Porn-induced ED, as it’s commonly referred to, occurs when your porn habits affect your sexual tastes, expectations and perceptions. Porn consumption can potentially result in anxiety around sex, which can contribute to erectile dysfunction.

Since this is a psychological cause of ED, it often isn’t fully treated with medications like Cialis, Viagra, Stendra or Levitra. Our guide to porn-induced ED explains this phenomenon in more detail and shares techniques that you can use to avoid letting porn affect your sex life. 

Common Side Effects of Cialis to Keep in Mind

According to the FDA, common side effects include:

  • headache

  • indigestion

  • back pain

  • muscle pain

  • flushing

  • stuffy nose 

More serious side effects include:

  • chest pain

  • heart attack

  • low blood pressure

  • allergic reaction

Another ED Medication is More Suitable for You

Cialis is one of several medications used to treat erectile dysfunction. Because Cialis has a longer half-life than other ED medications, it’s typically prescribed to men affected by ED who need a long-lasting treatment option.

Although all PDE5 inhibitors work similarly, some men seem to prefer the effects of one drug over those of others. If you’re not satisfied with Cialis, talk to your healthcare provider about the possibility of using a different ED medication that’s more suitable for your needs.

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How Cialis Works: Final Thoughts

Dealing with erectile dysfunction can be a frustrating experience, especially if you don’t get the results you anticipated from medications like Cialis. However, it’s worth remembering that there are real, proven, science-backed treatment options available that can help you.

In our guide to the most effective ED treatments, we list a wide range of treatment options that can help you get and maintain an erection during sex, improve your overall sexual performance and enjoy a better sex life.

15 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

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  2. Bellastella, et al. (2014, March 6). Diabetes and sexual dysfunction: Current perspectives. Diabetes, metabolic syndrome and obesity : targets and therapy. Retrieved June 10, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949699/
  3. Buvat, et al. (2015, November 12). Tadalafil 5 mg once daily for the treatment of erectile dysfunction during a 6-month observational study (EDATE): Impact of patient characteristics and Comorbidities. BMC urology. Retrieved June 10, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4643510/
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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. Learn more about our editorial standards here.