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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Phosphodiesterase 5 Inhibitor [EPC]
Tadalafil is a potent, long-acting phosphodiesterase type 5 (PDE5) inhibitor indicated for the treatment of erectile dysfunction, signs and symptoms of benign prostatic hyperplasia, and pulmonary arterial hypertension.
Name
Tadalafil
Raw Name
TADALAFIL
Category
Phosphodiesterase 5 Inhibitor [EPC]
Drug Count
9
Variant Count
250
Last Verified
February 17, 2026
RxCUI
402019, 403957, 484814, 757707, 2123194, 2613563, 2613569, 2110455, 2677765, 2677771, 2677773, 2677775, 849866, 402096, 402097, 404711, 762660
UNII
742SXX0ICT, UCE6F4125H, Z9K9Y9WMVL
About Tadalafil
Tadalafil is a potent, long-acting phosphodiesterase type 5 (PDE5) inhibitor indicated for the treatment of erectile dysfunction, signs and symptoms of benign prostatic hyperplasia, and pulmonary arterial hypertension.
Detailed information about Tadalafil
This page is for informational purposes only and does not replace medical advice. Consult a qualified healthcare professional before using any medication containing Tadalafil.
Beyond its well-known application in treating erectile dysfunction (ED), Tadalafil is also FDA-approved for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH), a condition characterized by an enlarged prostate gland that can cause significant urinary discomfort. Furthermore, in higher dosages, it is utilized to improve exercise capacity in patients with pulmonary arterial hypertension (PAH), a serious condition involving high blood pressure in the vessels carrying blood to the lungs. The drug's versatility stems from its ability to facilitate smooth muscle relaxation in various vascular beds, including the corpora cavernosa of the penis, the prostate, the bladder neck, and the pulmonary vasculature.
To understand how Tadalafil functions, one must look at the biochemical pathway involving nitric oxide (NO) and cyclic guanosine monophosphate (cGMP). During sexual stimulation, nitric oxide is released in the corpus cavernosum (the spongy tissue of the penis). This nitric oxide activates the enzyme guanylate cyclase, which in turn increases the levels of cGMP. This molecule, cGMP, is responsible for causing smooth muscle relaxation and increasing blood flow into the penis, resulting in an erection.
Under normal physiological conditions, an enzyme called phosphodiesterase type 5 (PDE5) breaks down cGMP, leading to the loss of the erection. Tadalafil works by selectively and reversibly inhibiting the PDE5 enzyme. By blocking the degradation of cGMP, Tadalafil enhances the effect of nitric oxide, allowing for sustained smooth muscle relaxation and improved blood flow. It is crucial to note that Tadalafil does not cause an erection in the absence of sexual stimulation; it merely facilitates the natural physiological response to arousal. In the context of BPH, the exact mechanism is still being studied, but it is believed that the inhibition of PDE5 leads to increased cGMP levels in the smooth muscle of the prostate and bladder, reducing muscle tone and improving urinary flow. In PAH, the inhibition of PDE5 increases cGMP in the pulmonary vascular smooth muscle cells, leading to vasodilation (widening of the blood vessels) and decreased pulmonary artery pressure.
Following oral administration, Tadalafil is rapidly absorbed. Unlike some other PDE5 inhibitors, the rate and extent of Tadalafil absorption are not significantly affected by food intake, meaning it can be taken with or without meals. The mean peak plasma concentration (Cmax) is typically reached within 2 hours (Tmax) after dosing. The absolute bioavailability of Tadalafil after oral dosing has not been fully determined in humans, but it is known to be highly effective in systemic circulation.
The mean volume of distribution for Tadalafil is approximately 63 liters, indicating that the drug is distributed into the tissues. At therapeutic concentrations, approximately 94% of Tadalafil in plasma is bound to proteins (primarily albumin and alpha-1-acid glycoprotein). This high protein binding contributes to its long half-life, as only the unbound fraction is pharmacologically active and available for metabolism.
Tadalafil is predominantly metabolized by the hepatic cytochrome P450 (CYP) 3A4 isoform. The primary circulating metabolite is the methylcatechol glucuronide. This metabolite is at least 13,000-fold less potent than Tadalafil for PDE5; therefore, it is not expected to be clinically active at observed metabolite concentrations. Because it relies heavily on the CYP3A4 pathway, Tadalafil is subject to significant drug-drug interactions with inhibitors or inducers of this enzyme system.
The mean oral clearance for Tadalafil is 2.5 L/hr, and the mean terminal half-life is approximately 17.5 hours in healthy subjects. This extended half-life allows for once-daily dosing or on-demand dosing with a long window of opportunity. Tadalafil is excreted predominantly as inactive metabolites, mainly in the feces (approximately 61% of the dose) and to a lesser extent in the urine (approximately 36% of the dose).
Tadalafil is indicated for the treatment of erectile dysfunction. It is available for use as needed (typically 10mg or 20mg) or as a daily low-dose regimen (2.5mg or 5mg). The daily regimen is particularly beneficial for men who anticipate sexual activity more than twice a week or those who also suffer from BPH.
Tadalafil (5mg daily) is approved for the treatment of the signs and symptoms of BPH. It helps reduce urinary urgency, frequency, and the sensation of incomplete bladder emptying by relaxing the smooth muscles of the prostate and bladder.
Under the brand name Adcirca, Tadalafil (40mg once daily) is used to improve exercise ability in patients with PAH (WHO Group 1). By relaxing the blood vessels in the lungs, it reduces the workload on the heart.
Tadalafil is primarily available in the following oral tablet strengths:
> Important: Only your healthcare provider can determine if Tadalafil is right for your specific condition. A thorough medical evaluation is necessary to ensure the drug is safe for your cardiovascular health and to rule out underlying causes of your symptoms.
The dosage of Tadalafil varies significantly depending on the condition being treated and the patient's response to the medication. Healthcare providers will tailor the dose to achieve the best clinical outcome while minimizing side effects.
Tadalafil is generally not indicated for use in the pediatric population. Its safety and efficacy have not been established in children under the age of 18 for ED or BPH. In rare cases, specialized pediatric cardiologists may prescribe it off-label for certain pulmonary conditions, but this must only be done under strict expert supervision.
No specific dose adjustments are required for otherwise healthy elderly patients (over 65 years). However, because older adults are more likely to have decreased renal or hepatic function, healthcare providers should monitor these patients closely and adjust the dose if necessary.
If you are taking Tadalafil on a daily schedule and miss a dose, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and resume your regular schedule. Never take two doses at once to make up for a missed one.
Symptoms of a Tadalafil overdose may include severe versions of the common side effects, such as extreme dizziness, fainting, or a painful, prolonged erection. If an overdose is suspected, contact a poison control center or seek emergency medical attention immediately. Standard supportive measures should be employed. Hemodialysis contributes negligibly to tadalafil elimination.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or frequency without medical guidance, as this increases the risk of cardiovascular complications.
Most side effects of Tadalafil are mild to moderate and typically resolve within a few hours or days as the body adjusts to the medication. Common side effects include:
While rare, some side effects are medical emergencies. You must stop using Tadalafil and seek help immediately if you experience:
> Warning: Stop taking Tadalafil and call your doctor immediately if you experience any of these serious symptoms. Do not take another dose until cleared by a medical professional.
Clinical studies on daily use of Tadalafil for up to two years have shown that the drug is generally well-tolerated. However, long-term use requires ongoing monitoring of blood pressure and cardiovascular health. There is no evidence that Tadalafil causes 'dependency' in a physical sense, but patients should be monitored for psychological reliance on the medication for sexual performance.
No FDA black box warnings currently exist for Tadalafil. However, the contraindication regarding nitrates is treated with the same level of clinical gravity as a black box warning. Combining Tadalafil with any form of organic nitrate (such as nitroglycerin) can cause a life-threatening drop in blood pressure.
Report any unusual symptoms or side effects that persist or worsen to your healthcare provider. You may also report side effects to the FDA at 1-800-FDA-1088.
Tadalafil is a potent vasodilator (vessel widener). Before starting treatment, a healthcare provider must perform a physical examination and take a complete medical history to diagnose the condition and determine if Tadalafil is safe. Because sexual activity carries a potential cardiac risk for patients with pre-existing cardiovascular disease, Tadalafil should not be used in men for whom sexual activity is inadvisable due to their underlying cardiovascular status.
There are no official FDA black box warnings for Tadalafil. However, the most significant clinical warning involves the co-administration of nitrates. The use of Tadalafil and organic nitrates or nitrites (like 'poppers') is strictly prohibited due to the risk of severe, potentially fatal hypotension (low blood pressure).
Patients should not use Tadalafil if they have had a heart attack (myocardial infarction) within the last 90 days, unstable angina, or heart failure (New York Heart Association Class 2 or greater) in the last 6 months. It is also contraindicated in patients with uncontrolled arrhythmias (irregular heartbeats), hypotension (<90/50 mm Hg), or uncontrolled hypertension.
Physicians should advise patients to stop use of all PDE5 inhibitors and seek medical attention in the event of a sudden loss of vision in one or both eyes. Such an event may be a sign of non-arteritic anterior ischemic optic neuropathy (NAION), a rare condition. Risk factors include low cup-to-disc ratio ('crowded disc'), age over 50, diabetes, hypertension, and smoking.
Sudden decrease or loss of hearing has been reported in temporal association with the intake of PDE5 inhibitors. If this occurs, stop Tadalafil immediately and consult a doctor.
Because Tadalafil is cleared by the liver and kidneys, patients with significant impairment in these organs require lower doses or may be advised to avoid the medication entirely to prevent toxic accumulation.
Tadalafil should be used with caution in patients with anatomical deformation of the penis (such as angulation, cavernous fibrosis, or Peyronie's disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell anemia, multiple myeloma, or leukemia).
Patients on Tadalafil do not typically require routine blood monitoring specifically for the drug levels. However, healthcare providers may monitor:
Tadalafil has a minor influence on the ability to drive and use machines. Although dizziness has been reported in clinical trials, the frequency was low. Patients should be aware of how they react to Tadalafil before driving or operating machinery.
Both Tadalafil and alcohol are mild vasodilators. When taken in combination, they can increase the risk of orthostatic signs and symptoms, including increased heart rate, decreased standing blood pressure, dizziness, and headache. Patients should be advised that substantial consumption of alcohol (e.g., 5 units or more) in combination with Tadalafil may increase the potential for these symptoms.
For patients taking Tadalafil daily for BPH or ED, there is no physical withdrawal syndrome associated with stopping the medication. However, the symptoms of the underlying condition (e.g., urinary difficulty or erectile dysfunction) will likely return to their baseline levels once the drug is discontinued. No tapering is required.
> Important: Discuss all your medical conditions, especially heart rhythm problems or eye diseases, with your healthcare provider before starting Tadalafil.
Tadalafil is not known to significantly interfere with common laboratory tests, such as blood chemistry panels, complete blood counts, or urinalysis. However, it is always important to inform laboratory staff of all medications you are taking.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. A complete list is essential to prevent dangerous drug-drug interactions.
Absolute contraindications are conditions or situations where Tadalafil must never be used because the risks far outweigh any potential benefits.
Relative contraindications require a careful risk-benefit analysis by a physician. The drug may be used, but with extreme caution and monitoring.
While Tadalafil is chemically distinct from sildenafil and vardenafil, they all share the same primary mechanism of action. If a patient has experienced a serious adverse reaction (like NAION or sudden hearing loss) with one PDE5 inhibitor, they are generally advised to avoid the entire class, including Tadalafil, due to the high risk of cross-sensitivity for that specific adverse event.
> Important: Your healthcare provider will evaluate your complete medical history, including cardiac stress tests if necessary, before prescribing Tadalafil.
Tadalafil is classified as FDA Pregnancy Category B. This means that animal reproduction studies (in rats and rabbits) have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women. Tadalafil is not indicated for use in women except for the treatment of Pulmonary Arterial Hypertension (PAH). In the context of PAH, a physician must weigh the risks of untreated hypertension in the mother against the potential unknown risks to the fetus.
It is not known whether Tadalafil is excreted in human breast milk. Because many drugs are excreted in human milk, caution should be exercised when Tadalafil is administered to a nursing woman. Animal studies have shown that Tadalafil is excreted in the milk of lactating rats. A decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Tadalafil is not approved for use in pediatric patients for erectile dysfunction or BPH. While it is sometimes used off-label for pediatric pulmonary hypertension, this is done only in specialized centers. There is no data on the effects of Tadalafil on the growth or development of children.
In clinical trials, approximately 25% of subjects were 65 years of age or older. No overall differences in safety or effectiveness were observed between these subjects and younger subjects. However, older subjects may have a higher sensitivity to the drug's effects due to age-related declines in renal or hepatic function. The area under the curve (AUC)—a measure of drug concentration—is approximately 25% higher in healthy elderly subjects compared to younger subjects, suggesting that the drug stays in the system longer in the elderly.
In subjects with renal insufficiency, the Tadalafil AUC is approximately doubled.
Tadalafil exposure (AUC) in subjects with mild-to-moderate hepatic impairment (Child-Pugh Class A and B) is comparable to exposure in healthy subjects.
> Important: Special populations require individualized medical assessment. Always disclose your full medical history to your specialist.
Tadalafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). When sexual stimulation causes the local release of nitric oxide, the inhibition of PDE5 by Tadalafil leads to increased levels of cGMP in the corpus cavernosum. This results in smooth muscle relaxation and the inflow of blood into the penile tissues, thereby producing an erection. In the pulmonary vasculature, the same mechanism leads to vasodilation of the pulmonary arterial bed and, to a lesser degree, the systemic circulation. Tadalafil is more than 10,000 times more potent for PDE5 than for PDE1, PDE2, and PDE4, which are found in the heart, brain, and blood vessels. It is also significantly more selective for PDE5 than for PDE6, which is found in the retina and is responsible for phototransduction.
The onset of action for Tadalafil is typically 30 to 60 minutes, though some men may respond sooner. The duration of effect is the longest in its class, with efficacy maintained for up to 36 hours. This does not mean a continuous erection, but rather the ability to achieve one during that window if stimulated. Dose-response studies show that increasing the dose from 10mg to 20mg increases efficacy but also the incidence of side effects like headache and back pain.
| Parameter | Value |
|---|---|
| Bioavailability | Not precisely determined (high absorption) |
| Protein Binding | 94% |
| Half-life | 17.5 hours |
| Tmax | 2 hours |
| Metabolism | Hepatic (CYP3A4) |
| Excretion | Fecal 61%, Renal 36% |
Tadalafil is classified therapeutically as a Urological Agent and specifically as a Phosphodiesterase 5 Inhibitor. It shares this class with sildenafil (Viagra), vardenafil (Levitra), and avanafil (Stendra). Within the context of PAH, it is considered a pulmonary vasodilator.
Common questions about Tadalafil
Tadalafil is primarily used to treat three distinct medical conditions: erectile dysfunction (ED), the signs and symptoms of benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension (PAH). For ED, it helps men achieve and maintain an erection by increasing blood flow to the penis during sexual stimulation. For BPH, it relaxes the muscles in the prostate and bladder to improve urinary symptoms like urgency and weak flow. When used for PAH, it widens the blood vessels in the lungs to lower blood pressure and improve the patient's ability to exercise. It is a versatile medication that works by targeting the PDE5 enzyme in various parts of the body.
The most common side effects reported by patients taking Tadalafil include headaches, indigestion (dyspepsia), back pain, muscle aches (myalgia), nasal congestion, and facial flushing. Most of these side effects are related to the drug's ability to dilate blood vessels and usually disappear within a few hours. Back pain and muscle aches are unique to Tadalafil and typically occur 12 to 24 hours after taking the dose, resolving on their own within two days. While most side effects are mild, it is important to monitor how your body reacts. If any side effect becomes severe or persistent, you should consult your healthcare provider for guidance.
Moderate alcohol consumption (such as one or two glasses of wine or one beer) typically does not cause significant issues when taking Tadalafil. However, both Tadalafil and alcohol act as mild vasodilators, which means they both lower blood pressure by widening blood vessels. Consuming large amounts of alcohol while taking this medication can lead to a significant drop in blood pressure, resulting in dizziness, a rapid heart rate, or fainting. To ensure safety, it is best to limit alcohol intake and observe how the combination affects you. Always discuss your alcohol habits with your doctor before starting a new prescription.
Tadalafil is generally not indicated for use in women, except for those treated for pulmonary arterial hypertension (PAH). It is classified as FDA Pregnancy Category B, meaning animal studies have not shown harm to the fetus, but there is a lack of rigorous data in pregnant humans. If a woman with PAH becomes pregnant while taking Tadalafil, she must consult her specialist immediately to weigh the risks and benefits. It is unknown if the drug passes into breast milk, so nursing mothers should also seek medical advice. For most women, the drug is not recommended unless specifically prescribed for life-threatening pulmonary conditions.
For most men, Tadalafil begins to work within 30 to 60 minutes after ingestion, though the exact timing can vary based on individual metabolism. Unlike some other medications in its class, its absorption is not significantly affected by food, so it can be taken with or without a meal. It is important to remember that Tadalafil does not produce an automatic erection; sexual stimulation is still required for the medication to be effective. Because the drug stays in the system for up to 36 hours, many patients find they do not need to rush and can choose a time for sexual activity that feels natural. For daily use, the drug builds up to a steady state in the body over about five days.
Yes, you can generally stop taking Tadalafil suddenly without experiencing physical withdrawal symptoms, as it is not an addictive substance. However, if you are taking it daily for conditions like benign prostatic hyperplasia (BPH) or pulmonary arterial hypertension (PAH), your symptoms will likely return once the medication is out of your system. If you are taking it for PAH, stopping the drug could lead to a dangerous increase in pulmonary blood pressure, so you should never stop without consulting your cardiologist. For erectile dysfunction, stopping the drug simply means the benefits to your sexual function will cease. Always discuss your reasons for stopping with your doctor to ensure a safe transition.
If you are on a daily dosing schedule for Tadalafil and you miss a dose, you should take it as soon as you remember. If it is already close to the time for your next scheduled dose, skip the missed dose and continue with your regular routine. You should never take two doses at the same time or extra doses to make up for the one you missed, as this increases the risk of side effects like severe headache or low blood pressure. If you are taking Tadalafil on an as-needed basis for erectile dysfunction, a missed dose is not applicable—you simply take it when required. Consistency is most important for those treating BPH or PAH.
Weight gain is not a recognized or common side effect of Tadalafil based on extensive clinical trial data and post-marketing surveillance. The medication works on the vascular system and smooth muscles and does not typically interfere with metabolic processes or appetite in a way that would lead to weight changes. If you experience sudden weight gain or swelling (edema) while taking Tadalafil, it could be a sign of an underlying heart or kidney issue, rather than a direct effect of the drug itself. In such cases, you should contact your healthcare provider for an evaluation. Always track any unusual physical changes when starting a new medication.
Tadalafil can interact with several other medications, some of which can be very dangerous. It must never be taken with nitrates (used for chest pain) or guanylate cyclase stimulators, as the combination can cause a fatal drop in blood pressure. It also interacts with alpha-blockers used for prostate issues, certain antibiotics, antifungal medications, and HIV protease inhibitors, which can increase the levels of Tadalafil in your blood. Because of these potential interactions, it is vital to provide your doctor with a complete list of all prescriptions, over-the-counter drugs, and herbal supplements you are taking. Your doctor may need to adjust your dose to ensure your safety.
Yes, Tadalafil is widely available as a generic medication, which is typically much more affordable than the brand-name versions, Cialis or Adcirca. Generic Tadalafil contains the same active ingredient and is required by the FDA to meet the same standards of quality, strength, and purity as the brand-name drug. It is available in the same strengths (2.5mg, 5mg, 10mg, and 20mg) and is used for the same indications. When your doctor writes a prescription for Tadalafil, you can usually choose the generic version at your pharmacy. Always ensure you are purchasing from a reputable, licensed pharmacy to avoid counterfeit products.