Cialis: Uses, dosage, side effects, warnings & patient reviews

What is Cialis (Tadalafil)?

Cialis is the brand name for the prescription drug tadalafil. It is classified as a phosphodiesterase type 5 (PDE5) inhibitor. This medication is indicated for the treatment of erectile dysfunction (ED) in adult men and for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH).

Its primary mechanism of action is the inhibition of the PDE5 enzyme, leading to increased levels of cyclic guanosine monophosphate (cGMP). This results in relaxation of smooth muscle tissue and increased blood flow in specific areas of the body, depending on the condition being treated.

A key pharmacokinetic characteristic of tadalafil is its extended half-life of approximately 17.5 hours, which allows for a prolonged duration of therapeutic effect compared to other medications in its class.

How to Take Cialis

Cialis is available in two primary dosing regimens, which are prescribed based on the specific medical indication.

For Erectile Dysfunction (ED)

• As-needed dosing: A single tablet is taken prior to anticipated sexual activity. The recommended starting dose for most patients is 10 mg. Based on efficacy and tolerability, the dose may be increased to 20 mg or decreased to 5 mg. The medication may be taken at least 30 minutes before sexual activity and is effective for up to 36 hours.
• Once-daily dosing: A lower dose (2.5 mg or 5 mg) is taken once per day at approximately the same time, without regard to timing of sexual activity. This regimen is appropriate for patients who anticipate frequent sexual activity (e.g., twice weekly).

The choice between as-needed and once-daily dosing should be made in consultation with a physician. For a detailed analysis, refer to the guide on daily vs. as-needed Cialis.

For Benign Prostatic Hyperplasia (BPH)

The recommended dose for the treatment of the signs and symptoms of BPH is 5 mg taken once daily at approximately the same time each day.

Administration Notes

• Cialis may be taken with or without food; a high-fat meal does not alter its absorption to a clinically significant degree.
• The tablet should be swallowed whole with water.
• The maximum recommended dosing frequency is once per day.

Side Effects of Cialis

The use of Cialis (tadalafil) is associated with a range of possible adverse reactions, resulting from its vasodilatory effects. For a broader context on common side effects of ED medications, see this urologist’s guide.

What is Cialis Used For?

Cialis (tadalafil) is approved by the U.S. Food and Drug Administration (FDA) for two distinct indications in adult men.

Erectile Dysfunction (ED)

Cialis is indicated for the treatment of erectile dysfunction. It is effective when sexual stimulation occurs. The medication is not an aphrodisiac and does not increase libido.

Benign Prostatic Hyperplasia (BPH)

Cialis is indicated for the treatment of the signs and symptoms of benign prostatic hyperplasia. This includes the relief of lower urinary tract symptoms such as urinary frequency, urgency, weak stream, and nocturia. For more information on BPH and its treatment, see this guide to BPH medications.

Important Note on Use

Treatment with Cialis for either indication requires a diagnosis from a qualified healthcare professional. It should only be used under medical supervision.

Important Safety Concerns and Considerations

Cardiovascular Risk

Sexual activity presents a potential cardiac risk for patients with pre-existing cardiovascular disease. Cialis has vasodilatory properties that cause a mild, transient decrease in blood pressure. It is contraindicated in patients for whom sexual activity is not advised due to underlying cardiovascular status. Physicians should evaluate cardiovascular fitness prior to initiating treatment.

Effects on the Eye

Non-arteritic anterior ischemic optic neuropathy (NAION), a condition leading to sudden vision loss, has been reported rarely in temporal association with the use of PDE5 inhibitors, including tadalafil. Patients with a history of NAION in one eye have an increased risk of NAION in the other eye. Use in these patients should be undertaken with caution.

Hearing Impairment

Sudden decrease or loss of hearing, sometimes accompanied by tinnitus and dizziness, has been reported in temporal association with the intake of PDE5 inhibitors, including tadalafil. A causal relationship has not been definitively established, but patients experiencing such symptoms should discontinue Cialis and seek prompt medical attention.

Prolonged Erection and Priapism

Prolonged erection exceeding 4 hours and priapism (a painful erection lasting more than 6 hours) have been reported infrequently. Priapism requires immediate medical intervention to avoid permanent damage to penile tissues and subsequent erectile dysfunction.

Critical Warnings for Cialis Use

Contraindication with Nitrates

The use of Cialis is strictly contraindicated in patients who are using any form of organic nitrate or nitric oxide donor, either regularly or intermittently. This includes nitroglycerin, isosorbide mononitrate/dinitrate, and recreational amyl nitrite (“poppers”). The co-administration can cause a profound and life-threatening drop in blood pressure. Patients with heart disease who may use nitrates require particular caution.

Concomitant Use with Alpha-Blockers and Antihypertensives

Cialis may augment the blood-pressure-lowering effect of alpha-blockers and other antihypertensive medications. Concomitant use with alpha-blockers is not recommended except if the patient is stable on his alpha-blocker therapy. In such cases, initiating Cialis at the lowest possible dose (2.5 mg for daily or 5 mg for as-needed) is advised.

Renal and Hepatic Impairment

Dosage adjustments are recommended for patients with significant renal impairment. For patients with severe renal impairment (creatinine clearance less than 30 mL/min), the recommended dose for ED is 5 mg not more than once every 72 hours, and the daily dose for ED or BPH should not exceed 2.5 mg. Cialis is not recommended for use in patients with severe hepatic impairment (Child-Pugh Class C).

Underlying Etiology of ED and BPH

Prior to initiating treatment, a medical evaluation should be conducted to determine the underlying cause of ED or the urinary symptoms of BPH. Cialis treats the symptoms but does not alter the underlying pathophysiology.

Cialis Dosage Information

The appropriate dosage of Cialis (tadalafil) is determined by the treating physician based on the indication, patient’s health status, and tolerability. The following table outlines the standard dosing regimens.

Important Administration Notes

• Missed Dose (Daily Dosing): If a daily dose is missed, it should be taken as soon as remembered. If it is almost time for the next dose, the missed dose should be skipped. A double dose should not be taken to make up for a missed dose.
• Dose Adjustments: Lower doses are recommended for patients with renal or moderate hepatic impairment, and for those taking concomitant potent CYP3A4 inhibitors (e.g., ketoconazole, ritonavir).
• Duration of Effect: For the as-needed 10 mg or 20 mg dose, the effect may last up to 36 hours. This does not imply a continuous erection but rather the ability to achieve an erection with stimulation during this window.

Drug Interactions with Cialis

Cialis (tadalafil) is metabolized primarily by the CYP3A4 enzyme system. Its pharmacokinetics and effects can be significantly altered by concomitant medications, necessitating a thorough review by a healthcare provider.

Additional Information

Available Forms and Strengths

Cialis (tadalafil) is available as film-coated, almond-shaped tablets in the following strengths for oral administration: 2.5 mg, 5 mg, 10 mg, and 20 mg. Other formulations, such as Cialis Professional, may also be available.

Storage and Handling

Store at 25°C (77°F); excursions permitted between 15°C and 30°C (59°F and 86°F). Keep in the original container to protect from moisture and light. Keep out of reach of children and pets.

Historical Context

Tadalafil was discovered and developed by the biotechnology company ICOS, and later co-marketed with Eli Lilly and Company. It received FDA approval for the treatment of erectile dysfunction in November 2003. Its approval for the signs and symptoms of benign prostatic hyperplasia followed in October 2011.

Reporting Side Effects

Patients are encouraged to report negative side effects of prescription drugs to their healthcare provider and to the relevant national regulatory authority (e.g., the FDA’s MedWatch program in the United States).

References and Medical Sources

1. U.S. Food and Drug Administration (FDA). Cialis (tadalafil) Prescribing Information. [Revised 2023]. https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/021368s20s21lbl.pdf
2. MedlinePlus. Tadalafil. U.S. National Library of Medicine; [Updated 2024]. https://medlineplus.gov/druginfo/meds/a604008.html
3. American Urological Association (AUA). Erectile Dysfunction: AUA Guideline (2018). https://www.auanet.org/guidelines/guidelines/erectile-dysfunction-(ed)-guideline
4. American Urological Association (AUA). Management of Benign Prostatic Hyperplasia/Lower Urinary Tract Symptoms: AUA Guideline (2021). https://www.auanet.org/guidelines/guidelines/benign-prostatic-hyperplasia-(bph)-guideline

Disclaimer: The information on this site is provided for informational purposes only and is not medical advice. It does not replace professional medical consultation, diagnosis, or treatment. Do not self-medicate based on the information presented on this site. Always consult with a doctor or other qualified healthcare professional before making any decisions about your health.