How Long Does Cialis Stay In Your System?

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What is Cialis?

Cialis¹ (tadalafil) is an erectile dysfunction (ED) treatment that works by increasing blood flow to the penis. Compared to other ED treatments, Cialis works much longer, with a one-and-a-half-day enhancement window. Other ED medications, like Viagra, typically only last for hours, not days.  

What is Cialis prescribed for?

Cialis is intended for patients with erectile dysfunction or benign prostatic hyperplasia (an enlarged prostate). 

How does Cialis treat ED?

An erection generally results from mental or physical stimulation. It occurs when arousal causes the muscles of your penis to relax, allowing blood to flow into the spongy tissue in your penis, called the corpora cavernosa. 

When this happens, the blood in your penis causes it to become firm, resulting in an erection. 

Additionally, a sheath surrounding the corpora cavernosa helps to stop the blood from leaving your penis, helping you stay hard. In most cases, ED results from a lack of blood flow to the penis or an inability to trap the blood during an erection. The former leads to an inability to get an erection, while the latter makes it difficult to sustain one. 

Cialis² works by inhibiting an enzyme called phosphodiesterase-5³ (PDE5), which blocks a messenger molecule called cyclic guanosine monophosphate⁴ (cGMP). cGMP plays a key role in expanding blood vessels to promote blood flow, so by inhibiting PDE5 and boosting cGMP, Cialis improves blood flow to the penis and enhances erectile functioning.

Is Cialis safe to take for ED?

Cialis is FDA approved for the treatment of ED (and BPD). Therefore, in general, Cialis is considered safe when used as prescribed. However, some people with heart or liver issues shouldn’t take Cialis.

Beyond that, there are known interactions between Cialis and some foods (most notably, grapefruit) and drugs (alpha-blockers, antifungals, high blood pressure medications, and more). 

Grapefruit and Cialis affect the same enzymes in the body. Combining the two can relax your blood vessels, resulting in hypotension (low blood pressure). 

Additionally, excessive drinking results in low blood pressure and dizziness when taken with this medication. 

Medications known to interact with Cialis include:

  • Nitrates,⁵ which may be prescribed for angina, heart failure, or hypertension, and can lead to low blood pressure when taken with Cialis

  • Alpha-blockers,⁶ drugs commonly prescribed for high blood pressure and prostate enlargement that can cause low blood pressure if taken alongside Cialis

  • High blood pressure medications,⁷ which, combined with Cialis, can lower blood pressure too much

  • Fungal infection drugs (CYP3A4 inhibitors), can increase the amount of Cialis in the body per dose

  • Certain antibiotics (CYP3A4 inducers), can reduce the effectiveness of Cialis

When you visit your doctor to discuss treatment options for ED, bring along a list of the supplements, vitamins, and medications you’re taking, and mention any health conditions you have.

Benefits of Cialis

Cialis is well-known for its duration of effectiveness, that is, how long the drug works before you need to take another dose. Another top ED drug, Viagra, also works by inhibiting PDE5. However, Viagra only lasts 30 minutes to four hours, compared to Cialis’ 36 hours.

Cialis also works faster. While Viagra users need to plan at least an hour in advance, Cialis is effective in as little as 30 minutes. 

How should you take Cialis?

When your pharmacist dispenses Cialis, they’ll provide a leaflet with instructions on how to take the medication. In addition, there’s a pharmacy phone number on the bottle in case you’re unsure about something and need advice when you get home. You’ll take Cialis as needed or once daily, but never more than once within a 24-hour period. 

If you’re taking Cialis in anticipation of sexual activity, take it at least 30 minutes in advance. If you’re taking it daily, take it at about the same time each day. You can discuss the pros and cons of each method with your doctor.  

How long does it take Cialis to work?

When taken correctly, Cialis should start to work in an hour or less (and as little as 30 minutes for some men) and should be taken at least 30 minutes prior to sexual activity. One of the main benefits of Cialis is that its effects can last for up to 36 hours.

It is important to note that you must be sexually aroused during this period for Cialis to work as intended. Cialis will not trigger an erection unless you’re aroused.

How long does Cialis stay in your system?

 One dose of Cialis can stay in your system for more than two days. Certain health conditions involving the kidneys and liver and some medications can extend the window. Because Cialis stays in the system for a while, it’s essential you don’t exceed one dose per 24-hour period.

Side effects of Cialis

Almost all medications have some risk of side effects, ranging from mild to moderate, serious, and even life-threatening. The common and rare side effects of Cialis are listed below.  

Common side effects

  • Headache

  • Upset stomach

  • Back or limb pain

  • Muscle pain

  • Stuffy nose

  • Flushing (redness in the face)

  • Indigestion 

Less common and potentially serious side effects 

  • Sudden vision changes

  • Sudden decrease or loss of hearing

  • Dizziness

  • Painful or prolonged erection lasting four or more hours

  • Allergic reactions, including a rash, itching, swelling, dizziness, or trouble breathing

  • Seizures

See your doctor at your earliest convenience if you experience any mild and common side effects. However, if you experience any serious side effects, seek immediate medical attention. 

Other treatments for ED

ED is a common disorder, affecting up to 52% of men between 40 and 70. Fortunately, because it’s so common, there are many treatment options. PDE5 inhibitors, like Cialis, are often the first choice for doctors treating men with ED. Other PDE5 inhibitors include Viagra (sildenafil), Levitra (vardenafil), or Stendra (avanafil). 

Additionally, alternative therapies, such as acupuncture,⁸ may be effective in treating ED. Herbal supplements that show promise include L-arginine, red ginseng, and Pinus pinaster bark extract. Check with your doctor before trying herbal supplements, as they may interact with your medications or affect your medical conditions. 

One of the most effective interventions for improving ED is to change your lifestyle to become more healthy and active. 

If your ED is caused by anxiety, depression, or a mental block, speaking with a therapist can help. 

A penis pump and constriction ring⁹ may also be useful. These can help increase blood flow into the penis and stop blood from leaving the erection too quickly. 

Additionally, while it’s not widely used, there’s evidence¹⁰ that shockwave therapy may also be helpful in treating ED. 

If none of these interventions work for you, there are other options. In a study¹¹ of the effectiveness of injections administered directly into the penis, most participants reported that they could engage in sex successfully after injecting the medication.

A review of relevant literature¹² reports that penile implant surgery is safe and has a high success rate (though the exact satisfaction rate varies from study to study).

The lowdown

When it comes to treatments for ED, Cialis is a great option for men looking for long-term and long-acting medication. Cialis has many benefits, with its duration of effectiveness being its most attractive feature. 

However, it's essential to look for side effects and be aware of possible interactions between Cialis and other medications. Overall, Cialis is well-tolerated and effective for most men. If you’re interested in trying Cialis, schedule an appointment with your doctor, who will help you decide if it’s right for you.

  1. Questions and answers for Cialis (tadalafil) | U.S. Food and Drug Administration

  2. Cialis® (tadalafil) tablets | Access Data

  3. Phosphodiesterase-5 (PDE5) inhibitors In the management of erectile dysfunction (2013)

  4. Biochemistry, cyclic GMP | NIH: National Library of Medicine

  5. Nitrates | NIH: National Library of Medicine

  6. Alpha blockers | NIH: National Library of Medicine

  7. Antihypertensive medications | NIH: National Library of Medicine

  8. The efficacy of acupuncture on patients with erectile dysfunction: A review (2022)

  9. Diagnosis and treatment of erectile dysfunction– a practical update (2009)

  10. Low-intensity shock wave therapy and Its application to erectile dysfunction (2013)

  11. Efficacy and safety of intracavernosal alprostadil in men with erectile dysfunction list of authors (1996)

  12. Current role of penile implants for erectile dysfunction (2004)

Other Sources:

Have you considered clinical trials for Erectile dysfunction?

We make it easy for you to participate in a clinical trial for Erectile dysfunction, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

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