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

Mike Bohl, MD, MPH, ALM

Reviewed by Mike Bohl, MD, MPH, ALM

Written by Geoffrey C. Whittaker

Published 09/20/2020

Updated 02/14/2024

Like Viagra®, Stendra® and Levitra®, Cialis® is highly effective as a treatment for erectile dysfunction (ED). But 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 — not to mention side effects. 

Worrying about side effect risks while not seeing the results you want can be stressful, and it’s normal to worry if you’re not getting erections like you’d expect. 

We know you got here by searching questions like “how long for Cialis to work” and “how fast does Cialis work,” but understanding how Cialis works is the most important part of the picture. And while you’re at it, learning more about it will give you a better understanding of what to expect (and where to look for signs that the medication isn’t working).

Below, we’ve explained how this medication functions and why it might not be working. We’ve also shared some things you can do if Cialis doesn’t treat your ED.

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Oral ED medications like Cialis (and its generic, tadalafil) are also called phosphodiesterase type 5 or PDE5 inhibitors. PDE5 inhibitors like Cialis treat the symptoms of erectile dysfunction by inhibiting the PDE5 enzyme, which has the effect of keeping the smooth muscles in the arteries that supply blood to the penis relaxed. This makes it easier for blood to move into the erectile tissues of your penis, which leads to an erection.

Studies of tadalafil show that it improves erections and enhances sexual performance even at a relatively low dose. 

And unlike other PDE5 inhibitors and thanks to its long half-life, Cialis can provide relief from erectile dysfunction symptoms that lasts for 36 hours. 

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“How long does Cialis take to work” reveals a somewhat similar answer to other PDE5 inhibitors — for most people, Cialis typically begins working within 30 minutes to two hours. 

But depending on the Cialis dose you’re prescribed (and how you’re instructed to take it) that may mean different things for your ability to get and maintain an erection now, later and tomorrow.

Cialis is available in two dosage formats: as-needed for whenever the mood strikes, and once-daily for daily use. 

A daily dose works for you around-the-clock, helping you achieve an erection anytime you get aroused. As-needed doses, on the other hand, can work for up to 36 hours, but you need to make sure you’re taking it at the right time. 

If you’re concerned about making sure you’re prepared for performance and wondering when to take Cialis, it’s best to talk to a healthcare provider about any questions you may have. 

Sometimes things don’t work out the way we’d like, and that can be the case for medications that normally work for most people. What causes Cialis to deliver disappointing results can be a number of things, including:

  • The drug’s own efficacy

  • Using Cialis incorrectly

  • Using the wrong dose

  • Performance anxiety

  • ED caused by psychological issues

  • ED caused by more serious physical issues

  • Porn addiction

Let’s look at these reasons Cialis can fail in more detail.

Cialis Efficacy Statistics

According to Harvard Men's Health Watch, the active ingredients used in brand name medications Cialis, Viagra, Stendra and Levitra are only fully effective for healthy men around 70 percent of the time, meaning that many men still have erection issues even with the use of medication. It could be that the reason you have erectile dysfunction is something that Cialis doesn’t address, or it could be that — for whatever reason — Cialis works a little differently in your body.

It’s not ideal, of course. But hey, it’s better than nothing! 

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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’s generally recommended that for optimal results, you should:

  • Take Cialis at least 30 minutes to two hours before sex. How long does it take Cialis to work? Cialis can take up to two hours to start fully working inside your body. Since Cialis is a long-lasting medication, you can take it several hours before sex without having to worry about its effects wearing off.

  • Avoid drinking alcohol or taking recreational drugs. Not only can alcohol make Cialis and other medications less effective, 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.

Cialis may also be affected by interactions with other medications, as well as certain foods — like grapefruit juice. Yes, really. 

These warnings appear on the prescribing information labels approved by the U.S. Food and Drug Administration (FDA), but we’ll talk a little more about these interactions in a bit.

Additionally, Cialis doesn’t automatically give you an erection — you still need to be aroused to get hard. So even if you’ve taken Cialis correctly, if you aren’t getting stimulated by touch or erotic thoughts or images, you may not end up with an erection.

You’re Not Using the Right Dose of Cialis

“How long does Cialis take to kick in” may be the wrong question to ask when you’re a few hours in and Googling “Cialis not working.” Instead, the better question might be “am I taking the right dosage?”

Cialis comes in several doses: 2.5 mg, 5 mg, 10 mg and 20 mg. Most of the time, the 5 mg, 10 mg and 20 mg dosages are used as-needed for the treatment of erectile dysfunction.

Lower doses of Cialis, like 2.5 mg and 5 mg tablets, tend to be used as daily doses to treat mild ED and medical conditions such as benign prostatic hyperplasia (BPH). 

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, 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. You could even practice masturbating with it first, to see how things go.

If problems persist, let your healthcare provider know and see what they have to say. They may recommend a different dose, or even switch you to another ED medication altogether.

Your ED is Caused by a Psychological Condition

How long does it take for Cialis to work? Thirty to 120 minutes, assuming you’re also aroused enough to cause an erection. If, however, you’re distracted, fatigued, anxious or depressed, you may not get aroused at all

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

Erectile dysfunction can be associated with anxiety, stress and depression. If you have a mental illness or other condition that affects your sexual performance, the use of Cialis and other ED drugs might not be completely effective. 

If you think one of these conditions is the cause of your ED, your healthcare provider may suggest therapy, anxiety and depression medications, as well as other treatment options. 

Your ED is Caused by a Physical Health Condition

Erectile dysfunction is often caused by a physical health condition, such as: 

As we mentioned above, tadalafil, the active ingredient in Cialis, works by increasing blood flow to the erectile tissues of your penis. But if your ED is caused by another physical condition that doesn’t affect blood flow or causes decreased blood flow, or if your ED is particularly severe, it may not be completely treated by Cialis.

For example, issues like low testosterone can also 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 caused by low testosterone. 

Porn is Affecting Your Sexual Performance

If you frequently watch porn, it could negatively affect your sexual performance. Porn-induced ED affects your sexual tastes, expectations and perceptions. 

Porn consumption can also potentially result in anxiety around sex, which can contribute to erectile dysfunction.

Since this is a psychological cause of ED, it often can’t be 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. 

According to the FDA, the most common side effects of Cialis include:

  • Headache

  • Indigestion

  • Back pain

  • Muscle pain

  • Flushing of the skin

  • Stuffy nose 

More serious side effects include:

  • Vision loss

  • Hearing loss

  • Prolonged erection (also known as priapism)

Additionally, you’ll want to talk to your healthcare provider about the potential for drug interactions if you’re taking other medications. Among other medications, Cialis may interact in dangerous ways with any of the following:

  • Alpha-blockers

  • Nitrates like nitroglycerin and amyl nitrate

  • “Poppers” and other nitrites 

  • Antifungal medications like itraconazole and ketoconazole

  • Riociguat, a drug used to treat pulmonary hypertension

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Cialis works most of the time when it’s used correctly. But when you start “messing with the system,” so to speak, those changes and deviations can cause tadalafil to fail you. 

If you’re taking Cialis and not getting the results you want, remember some key points:

  • Dealing with erectile dysfunction can be a frustrating experience, especially if you don’t get the results you anticipated from medications like Cialis. 

  • These medications are real, proven, science-backed erectile dysfunction treatments though, and are generally effective when used correctly.

  • Using them incorrectly — having the wrong dosage or not following instructions — can cause Cialis not to work.

  • Cialis might also fail if your ED is related to psychological issues — performance anxiety, intimacy issues, low self-confidence and depression can all affect your erections.

  • FDA-approved prescription medications like Cialis are substantially more safe and effective than supplements you might get elsewhere.

So if Cialis is failing you, talk to a healthcare provider today about other options. They may adjust your dose, give you some tips or switch you to another medication. Whatever it takes, get your ED under control today — you deserve to enjoy sex.

11 Sources

  1. 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/
  2. 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/
  3. Center for Drug Evaluation and Research. (n.d.). Questions and answers for Cialis (Tadalafil). U.S. Food and Drug Administration. Retrieved June 10, 2022, from https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/questions-and-answers-cialis-tadalafil
  4. DRUGS@FDA: FDA-approved drugs. accessdata.fda.gov. (n.d.). Retrieved June 10, 2022, from https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&varApplNo=021368
  5. Fujimoto, et al. (2007, May). A comparison of the efficacy and tolerability of Tadalafil 10 mg and 20 mg in Japanese patients with severe erectile dysfunction. The journal of sexual medicine. Retrieved June 10, 2022, from https://www.ncbi.nlm.nih.gov/pubmed/17087800
  6. Labazi, et al. (2012, March). New insights into hypertension-associated erectile dysfunction. Current opinion in nephrology and hypertension. Retrieved June 10, 2022, from https://www.ncbi.nlm.nih.gov/pubmed/22240443
  7. Dhaliwal, A, Gupta, M. (2022). PDE5 Inhibitors. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.
  8. Reference ID: 3024692 - food and drug administration. (n.d.). Retrieved June 10, 2022, from https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/021368s20s21lbl.pdf
  9. Shridharani, A. N., & Brant, W. O. (2016, February). The treatment of erectile dysfunction in patients with neurogenic disease. Translational andrology and urology. Retrieved June 10, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4739980/
  10. Which drug for erectile dysfunction? Harvard Health. (2020, April 10). Retrieved June 10, 2022, from https://www.health.harvard.edu/mens-health/which-drug-for-erectile-dysfunction
  11. Zinner, N. (2007, January). Do food and dose timing affect the efficacy of sildenafil? A randomized placebo-controlled study. The journal of sexual medicine. Retrieved June 10, 2022, from https://www.ncbi.nlm.nih.gov/pubmed/17233779
Editorial Standards

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. See a mistake? Let us know at [email protected]!

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.

Mike Bohl, MD, MPH, ALM

Dr. Mike Bohl is a licensed physician, a Medical Advisor at Hims & Hers, and the Director of Scientific & Medical Content at a stealth biotech startup, where he is involved in pharmaceutical drug development. Prior to joining Hims & Hers, Dr. Bohl spent several years working in digital health, focusing on patient education. He has also worked in medical journalism for The Dr. Oz Show (receiving recognition for contributions from the National Academy of Television Arts and Sciences when the show won Outstanding Informative Talk Show at the 2016–2017 Daytime Emmy® Awards) and at Sharecare. He is a Medical Expert Board Member at Eat This, Not That! and a Board Member at International Veterinary Outreach.

Dr. Bohl obtained his Bachelor of Arts and Doctor of Medicine from Brown University, his Master of Public Health from Columbia University, and his Master of Liberal Arts in Extension Studies—Journalism from Harvard University. He is currently pursuing a Master of Business Administration and Master of Science in Healthcare Leadership at Cornell University. Dr. Bohl trained in internal medicine with a focus on community health at NYU Langone Health.

Dr. Bohl is Certified in Public Health by the National Board of Public Health Examiners, Medical Writer Certified by the American Medical Writers Association, a certified Editor in the Life Sciences by the Board of Editors in the Life Sciences, a Certified Personal Trainer and Certified Nutrition Coach by the National Academy of Sports Medicine, and a Board Certified Medical Affairs Specialist by the Accreditation Council for Medical Affairs. He has graduate certificates in Digital Storytelling and Marketing Management & Digital Strategy from Harvard Extension School and certificates in Business Law and Corporate Governance from Cornell Law School.

In addition to his written work, Dr. Bohl has experience creating medical segments for radio and producing patient education videos. He has also spent time conducting orthopedic and biomaterial research at Case Western Reserve University and University Hospitals of Cleveland and practicing clinically as a general practitioner on international medical aid projects with Medical Ministry International.

Dr. Bohl lives in Manhattan and enjoys biking, resistance training, sailing, scuba diving, skiing, tennis, and traveling. You can find Dr. Bohl on LinkedIn for more information.

Publications

  • Younesi, M., Knapik, D. M., Cumsky, J., Donmez, B. O., He, P., Islam, A., Learn, G., McClellan, P., Bohl, M., Gillespie, R. J., & Akkus, O. (2017). Effects of PDGF-BB delivery from heparinized collagen sutures on the healing of lacerated chicken flexor tendon in vivo. Acta biomaterialia, 63, 200–209. https://www.sciencedirect.com/science/article/abs/pii/S1742706117305652?via%3Dihub

  • Gebhart, J. J., Weinberg, D. S., Bohl, M. S., & Liu, R. W. (2016). Relationship between pelvic incidence and osteoarthritis of the hip. Bone & joint research, 5(2), 66–72. https://boneandjoint.org.uk/Article/10.1302/2046-3758.52.2000552

  • Gebhart, J. J., Bohl, M. S., Weinberg, D. S., Cooperman, D. R., & Liu, R. W. (2015). Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis. Journal of pediatric orthopedics, 35(6), 565–570. https://journals.lww.com/pedorthopaedics/abstract/2015/09000/pelvic_incidence_and_acetabular_version_in_slipped.5.aspx

  • Islam, A., Bohl, M. S., Tsai, A. G., Younesi, M., Gillespie, R., & Akkus, O. (2015). Biomechanical evaluation of a novel suturing scheme for grafting load-bearing collagen scaffolds for rotator cuff repair. Clinical biomechanics (Bristol, Avon), 30(7), 669–675. https://www.clinbiomech.com/article/S0268-0033(15)00143-6/fulltext

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