Cialis is a prescription medication containing the active ingredient tadalafil. It is a phosphodiesterase type 5 (PDE5) inhibitor approved for the treatment of erectile dysfunction (ED) and the signs and symptoms of benign prostatic hyperplasia (BPH).
ActiveIngredient:Tadalafil
DosageForm:Oral tablets
Dosage:2.5 mg, 5 mg, 10 mg, 20 mg
Indications:Treatment of erectile dysfunction (ED); Treatment of the signs and symptoms of benign prostatic hyperplasia (BPH); Treatment of ED and the signs and symptoms of BPH (ED/BPH).
Manufacturer:Eli Lilly and Company (Brand); generic manufacturers include Teva Pharmaceuticals, Aurobindo Pharma, and Torrent Pharmaceuticals.
Storage:Store at 25°C (77°F); excursions permitted to 15°C–30°C (59°F–86°F). Keep out of reach of children.
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.
General Instructions
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
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.
Reported Side Effects of Cialis (Tadalafil)
Frequency Category
Side Effects
Common
Headache, dyspepsia (indigestion), back pain, myalgia (muscle pain), nasal congestion, flushing, pain in limb.
Less Common
Dizziness, gastroesophageal reflux disease (GERD), visual disturbances (e.g., blurred vision, changes in color vision).
Serious (Seek Immediate Medical Attention)
Priapism: An erection lasting more than 4 hours.
Sudden hearing loss or tinnitus.
Sudden vision loss in one or both eyes (a symptom of non-arteritic anterior ischemic optic neuropathy, NAION).
Signs of a cardiovascular event (e.g., chest pain, shortness of breath during sexual activity).
Signs of a severe allergic reaction (e.g., rash, hives, swelling of the face/lips).
Uses
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.
Interactions Alcohol:
Use with caution
Both alcohol and tadalafil act as vasodilators. Concomitant use, particularly in excess, may potentiate vasodilatory effects such as orthostatic hypotension, dizziness, tachycardia, and headache. For detailed considerations, see this article on alcohol and ED medications.
Interactions Other Medications:
Consult your doctor
Cialis has significant and potentially dangerous interactions. It is absolutely contraindicated with any form of organic nitrate or nitric oxide donor. Concomitant use with alpha-blockers (e.g., tamsulosin) requires caution and possibly dose adjustment due to the risk of symptomatic hypotension. All concomitant medications must be reviewed by a prescribing physician.
Special Groups Pregnancy:
Unsafe
Cialis is not indicated for use in women, including during pregnancy.
Special Groups Breastfeeding:
Unsafe
Cialis is not indicated for use in women, including those who are breastfeeding.
Special Groups Elderly:
Use with caution
No dose adjustment is required based solely on age. However, greater sensitivity to the hypotensive effects or other adverse reactions is possible. Consideration of age-related decreases in renal function is also warranted.
Special Groups Children:
Unsafe
Cialis is not indicated for use in pediatric patients under 18 years of age.
Effects on Activities Driving:
Use with caution
Cialis can cause dizziness and somnolence. Patients should be aware of how they react to the medication before driving or operating complex machinery. For more on this topic, see this resource on medicines and driving.
Effects on Activities Operating Machinery:
Use with caution
The same caution regarding dizziness and somnolence applies to operating machinery.
Concerns
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.
Warnings
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.
Dosage
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.
Standard Dosing for Cialis (Tadalafil)
Indication
Dosage Regimen
Strength Options & Notes
Erectile Dysfunction (ED) – As-Needed
Take one tablet prior to anticipated sexual activity.
Starting dose: 10 mg
May increase to: 20 mg
May decrease to: 5 mg
Dosing frequency: Maximum once per day.
Erectile Dysfunction (ED) – Once-Daily
Take one tablet at the same time each day.
Recommended dose: 2.5 mg or 5 mg
Allows for spontaneous sexual activity.
Benign Prostatic Hyperplasia (BPH)
Take one tablet at the same time each day.
Recommended dose: 5 mg
ED and BPH (concomitant)
Take one tablet at the same time each day.
Recommended dose: 5 mg
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.
Interactions
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.
Significant Drug Interactions with Cialis (Tadalafil)
Profound hypotension, potentially life-threatening. Concomitant use is prohibited.
Alpha-Blockers
Tamsulosin, doxazosin, terazosin.
Additive blood pressure lowering, leading to symptomatic hypotension (dizziness, lightheadedness, fainting). Use with caution; initiate Cialis at lowest dose if patient is stable on alpha-blocker.
Markedly increases tadalafil exposure. For as-needed dosing, a maximum single dose of 10 mg every 72 hours is recommended. For daily dosing, the dose should not exceed 2.5 mg.
Potential for additive blood pressure-lowering effect. Monitoring is advised.
Alcohol
–
May increase vasodilatory symptoms (orthostatic hypotension, dizziness, tachycardia).
FAQs
Tadalafil has a half-life of approximately 17.5 hours. For the as-needed dose (10 mg or 20 mg), the therapeutic effect for erectile dysfunction may last up to 36 hours. This refers to the window of time during which a man may be able to achieve an erection with sexual stimulation. For more details, see this doctor's explanation.
The primary differences are duration of action and onset. Cialis (tadalafil) can be effective for up to 36 hours, whereas Viagra (sildenafil) is typically effective for 4-6 hours. Cialis is also approved for daily use in treating ED and the symptoms of BPH. For a comprehensive comparison, refer to this urologist's guide to ED pills.
Generic tadalafil contains the same active ingredient in the same strength as the brand-name product. Regulatory authorities require generic drugs to demonstrate bioequivalence, meaning they deliver the same amount of active ingredient into the bloodstream in the same timeframe. Therefore, generic tadalafil is therapeutically equivalent to Cialis. For other generic options, see Vidalista or Tadalista.
Brand-name prescription medications often have a higher cost due to research, development, and marketing. Cost-saving strategies may include using a generic version (tadalafil), using a pharmacy discount card, or exploring patient assistance programs if eligible. For practical advice, see this guide to making tadalafil affordable.
Several other FDA-approved PDE5 inhibitors are available for ED, such as sildenafil (Viagra), vardenafil, and avanafil. For BPH, other classes of medication like alpha-blockers or 5-alpha-reductase inhibitors may be options. Other non-oral treatments for ED include penile injections, vacuum erection devices, and surgical implants. A physician can determine the most appropriate alternative based on the individual's medical history.
Other Details
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).
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.
Thanks for sharing that, GymRat77. It’s interesting how clearly you noticed the similarity — when the experience feels the same and the only real difference is the price, that tends to stand out right away. Straightforward feedback like this is always useful to read.
You’re welcome! We’re glad you found the guide helpful in understanding how to take Cialis properly and determine the correct dosage. However, it’s essential to note that the information provided in the guide is general in nature. It’s always recommended to consult with a healthcare professional for personalized advice tailored to your specific needs and medical history. They can provide you with accurate dosage instructions and address any concerns you may have.
Cialis is still the best drug among all the treatments for male ed.
As I use cialis as a “weekend pill”, I can say that 100% it’s the most powerfull drug
today. If you want to try some drug during the party or any other time for spending it
with any amounts of alcohol, then you better not use viagra or any drugs containing
sildenafil. I’ve tried it several times and each time I had really strong side effects.
First of all- pain in the back, second one- headache. Both of them can easily spoil your
day completely.
Thanks for taking the time to write such a detailed comment, David. It’s very clear you’re speaking from real, repeated experience, and that comes through strongly. The way you described how different options felt for you — especially how side effects can completely change the whole experience — adds an important, honest perspective to the discussion.
I read the reviews on the forum and decided to try it myself. I was using it according to my own scheme, namely, one half of a pill before going to bed and second half at 25 minutes prior to intimacy. I have to admit that the effect was amazing. My penis stood above the sky for the whole day.
It’s important to use medications as prescribed and under the guidance of a healthcare professional. While it’s understandable that you wanted to experiment with the dosage based on forum reviews, it’s always recommended to consult with a healthcare professional for personalized advice. They can provide you with the appropriate dosage and usage instructions to ensure your safety and optimal results. Please remember to follow the prescribed dosage and consult with a healthcare professional for any concerns or adjustments.
Generic Cialis (Tadalafil) works just as well as the branded version. Honestly, I didn’t notice any difference except for the lower price!
Thanks for sharing that, GymRat77. It’s interesting how clearly you noticed the similarity — when the experience feels the same and the only real difference is the price, that tends to stand out right away. Straightforward feedback like this is always useful to read.
Thank for this guide on how to take and proper dosage for Cialis.
You’re welcome! We’re glad you found the guide helpful in understanding how to take Cialis properly and determine the correct dosage. However, it’s essential to note that the information provided in the guide is general in nature. It’s always recommended to consult with a healthcare professional for personalized advice tailored to your specific needs and medical history. They can provide you with accurate dosage instructions and address any concerns you may have.
Cialis is still the best drug among all the treatments for male ed.
As I use cialis as a “weekend pill”, I can say that 100% it’s the most powerfull drug
today. If you want to try some drug during the party or any other time for spending it
with any amounts of alcohol, then you better not use viagra or any drugs containing
sildenafil. I’ve tried it several times and each time I had really strong side effects.
First of all- pain in the back, second one- headache. Both of them can easily spoil your
day completely.
Thanks for taking the time to write such a detailed comment, David. It’s very clear you’re speaking from real, repeated experience, and that comes through strongly. The way you described how different options felt for you — especially how side effects can completely change the whole experience — adds an important, honest perspective to the discussion.
I read the reviews on the forum and decided to try it myself. I was using it according to my own scheme, namely, one half of a pill before going to bed and second half at 25 minutes prior to intimacy. I have to admit that the effect was amazing. My penis stood above the sky for the whole day.
It’s important to use medications as prescribed and under the guidance of a healthcare professional. While it’s understandable that you wanted to experiment with the dosage based on forum reviews, it’s always recommended to consult with a healthcare professional for personalized advice. They can provide you with the appropriate dosage and usage instructions to ensure your safety and optimal results. Please remember to follow the prescribed dosage and consult with a healthcare professional for any concerns or adjustments.