Tadalafil
PDE5 inhibitor for erectile dysfunction — up to 36-hour duration
Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor prescribed for the treatment of erectile dysfunction in adult men. It is distinguished from other PDE5 inhibitors by its prolonged duration of action — up to 36 hours from a single dose — and its availability as a once-daily low-dose regimen. Tadalafil requires a prescription and should only be taken under medical supervision. This article provides comprehensive, evidence-based information on how tadalafil works, dosage guidelines, potential side effects, drug interactions, and important safety precautions.
Quick Facts: Tadalafil
Key Takeaways
- Tadalafil is a long-acting PDE5 inhibitor with effects lasting up to 36 hours — significantly longer than other drugs in its class.
- It is available in two dosing strategies: as-needed (20 mg before activity) or once-daily (2.5–5 mg), making it the only PDE5 inhibitor approved for daily use at low doses.
- Tadalafil must never be combined with nitrates (e.g. nitroglycerin, amyl nitrite) or riociguat due to the risk of life-threatening hypotension.
- Common side effects include headache, back pain, muscle pain, nasal congestion, and facial flushing — these are generally mild and self-limiting.
- Seek immediate medical attention for an erection lasting more than 4 hours, sudden vision loss, or sudden hearing loss.
What Is Tadalafil and What Is It Used For?
Quick Answer: Tadalafil is a prescription medication belonging to the PDE5 inhibitor class. It is primarily used to treat erectile dysfunction in adult men by increasing blood flow to the penis during sexual stimulation. Its uniquely long duration of action (up to 36 hours) sets it apart from other medications in this class.
Tadalafil contains the active substance tadalafil, which belongs to a group of medicines known as phosphodiesterase type 5 (PDE5) inhibitors. Originally developed and marketed under the brand name Cialis by Eli Lilly, tadalafil is now available as generic formulations from multiple pharmaceutical manufacturers worldwide. It has been extensively studied in large-scale clinical trials and has a well-established safety and efficacy profile spanning more than two decades of clinical use.
The medication works by selectively inhibiting the enzyme PDE5, which is responsible for the breakdown of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the corpus cavernosum — the erectile tissue of the penis. When a man is sexually stimulated, nitric oxide is released into the erectile tissue, activating guanylate cyclase and increasing cGMP levels. This causes the smooth muscles to relax, allowing blood to flow into the penile arteries and fill the corpora cavernosa, producing an erection. Tadalafil enhances this natural physiological process by preventing the premature degradation of cGMP, thereby facilitating a more reliable and sustained erectile response.
What fundamentally distinguishes tadalafil from other PDE5 inhibitors such as sildenafil and vardenafil is its remarkably long half-life of approximately 17.5 hours. This pharmacokinetic property results in a duration of clinical effect of up to 36 hours following a single dose, which has earned tadalafil the colloquial name “the weekend pill.” This extended window of effectiveness allows for significantly greater spontaneity in sexual activity, as patients do not need to time their dose as precisely relative to planned intercourse.
It is important to understand that tadalafil only works when the patient is sexually aroused. The medication does not increase sexual desire, nor does it produce an erection without stimulation. The normal pathway of sexual arousal — involving psychological, hormonal, and neurological factors — must be activated for tadalafil to exert its effect. The foreplay and intimacy required for sexual activity remain the same as without medication.
Tadalafil is approved for the treatment of erectile dysfunction (ED) in adult men aged 18 and older. Erectile dysfunction is defined as the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance, and it is one of the most prevalent male sexual health conditions worldwide. According to the Massachusetts Male Aging Study and subsequent epidemiological research, approximately 52% of men between the ages of 40 and 70 experience some degree of ED, with prevalence increasing with age and the presence of comorbidities such as diabetes, cardiovascular disease, and depression.
In addition to its use for erectile dysfunction, tadalafil is approved in some countries for the treatment of benign prostatic hyperplasia (BPH) — a condition involving an enlarged prostate that causes urinary symptoms — and for pulmonary arterial hypertension (PAH). The dosing and indications for these conditions differ from those for ED, and this article focuses specifically on the use of tadalafil for erectile dysfunction.
What Should You Know Before Taking Tadalafil?
Quick Answer: Tadalafil is contraindicated with nitrate medications, riociguat, in patients with severe cardiovascular disease, after recent heart attack or stroke, and in those with uncontrolled blood pressure or a history of NAION. Always disclose your full medical history and all medications to your prescribing doctor.
Contraindications
There are several critical situations in which tadalafil must not be used. These absolute contraindications exist because combining tadalafil with certain medications or using it in the presence of specific medical conditions can result in severe, potentially fatal consequences. Understanding these restrictions is essential for patient safety.
- You are allergic to tadalafil or any of the other ingredients in the formulation
- You take any form of organic nitrates or nitric oxide donors, such as nitroglycerin (glyceryl trinitrate), isosorbide mononitrate, isosorbide dinitrate, or amyl nitrite — these are commonly used for angina (chest pain) and the combination can cause a severe, potentially fatal drop in blood pressure
- You have severe heart disease or have had a heart attack within the past 90 days
- You have had a stroke within the past 6 months
- You have low blood pressure (hypotension) or uncontrolled high blood pressure (hypertension)
- You have previously experienced non-arteritic anterior ischaemic optic neuropathy (NAION) — sometimes described as a “stroke of the eye” — which involves sudden loss of blood supply to the optic nerve
- You take riociguat, a medication used to treat pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension — PDE5 inhibitors have been shown to potentiate the blood-pressure-lowering effect of this drug
Warnings and Precautions
Before starting treatment with tadalafil, you should have a thorough discussion with your healthcare provider about your complete medical history. Sexual activity itself places additional physical demands on the cardiovascular system, and your doctor must assess whether your heart can safely handle this exertion. Several conditions require special caution, closer monitoring, or dosage adjustment when using tadalafil.
Talk to your doctor before taking tadalafil if you have any of the following conditions:
- Blood disorders: Sickle cell anaemia, multiple myeloma, or leukaemia — these conditions are associated with an increased risk of priapism (prolonged, painful erection)
- Penile abnormalities: Anatomical deformation of the penis, such as angulation, cavernosal fibrosis (Peyronie’s disease), or other structural conditions that may predispose to priapism
- Severe liver disease: Tadalafil is metabolised primarily by the liver, and impaired hepatic function may significantly alter drug exposure. Limited data are available for patients with severe hepatic impairment
- Severe kidney disease: Patients with severe renal impairment may experience increased drug exposure, requiring dosage adjustment and close monitoring
- Cardiovascular conditions: Any form of heart disease, including coronary artery disease, heart failure, or rhythm disorders, may require careful assessment of the safety of sexual activity
It is not known whether tadalafil is effective in patients who have undergone pelvic surgery or radical non-nerve-sparing prostatectomy (surgical removal of the prostate without preserving the nerves involved in erectile function). If you have had either of these procedures, discuss this with your doctor.
- Sudden vision loss or decrease — distorted, dimmed, blurred central vision or sudden visual impairment in one or both eyes. Stop tadalafil immediately and contact your doctor. This could indicate NAION or other serious ophthalmic conditions.
- Sudden hearing loss or decrease — with or without tinnitus (ringing in the ears) or dizziness. Although a causal relationship with tadalafil has not been established, prompt medical evaluation is essential.
Pregnancy and Breastfeeding
Tadalafil is not indicated for use in women. The medication has been developed and studied exclusively for the treatment of erectile dysfunction and related conditions in adult men. There are no adequate or well-controlled studies examining the effects of tadalafil in pregnant or breastfeeding women. If a female partner becomes accidentally exposed to the medication, she should consult a healthcare provider, although the risk of harm from incidental exposure is considered very low.
Children and Adolescents
Tadalafil for erectile dysfunction is not intended for use in children or adolescents under 18 years of age. The safety and efficacy of tadalafil for ED have not been established in the paediatric population, and there is no appropriate clinical indication for its use in this age group.
Fertility
In animal studies, a reduction in sperm parameters was observed when dogs were treated with tadalafil. In clinical studies involving human subjects, decreases in sperm count have also been noted in some men taking tadalafil. However, this reduction is generally considered unlikely to lead to infertility. If you are actively trying to conceive or have concerns about your reproductive health, discuss these findings with your doctor before starting treatment. The effect on sperm appears to be reversible following discontinuation of the medication.
Driving and Using Machines
Dizziness has been reported by some patients taking tadalafil in clinical trials. You should assess how you respond to the medication before driving a vehicle or operating machinery. If you experience dizziness, avoid activities that require alertness until the effect has resolved. These episodes are typically mild and transient.
How Does Tadalafil Interact with Other Drugs?
Quick Answer: Tadalafil has potentially dangerous interactions with nitrates and nitric oxide donors (absolute contraindication), riociguat, and alpha-blockers. CYP3A4 inhibitors (e.g. ketoconazole, ritonavir) increase tadalafil levels, while CYP3A4 inducers (e.g. rifampicin) decrease them. Always tell your doctor about all medications you take.
Drug interactions with tadalafil range from clinically insignificant to life-threatening. The most dangerous interaction is with nitrate-containing medications, which represents an absolute contraindication. Tadalafil is primarily metabolised by the cytochrome P450 enzyme CYP3A4, meaning that drugs which inhibit or induce this enzyme can significantly alter tadalafil plasma concentrations. It is essential to inform your healthcare provider about all prescription medications, over-the-counter drugs, herbal supplements, and recreational substances you are currently using.
Major Interactions (Contraindicated or Dangerous)
| Drug / Drug Class | Risk | Recommendation |
|---|---|---|
| Nitrates (nitroglycerin, isosorbide mononitrate, isosorbide dinitrate) | Severe, potentially fatal hypotension | Absolutely contraindicated — never combine |
| Amyl nitrite (“poppers”) and other nitric oxide donors | Severe hypotension | Absolutely contraindicated — never combine |
| Riociguat (for pulmonary hypertension) | Potentiation of hypotensive effects | Contraindicated — do not combine |
| Other PDE5 inhibitors (sildenafil, vardenafil, avanafil) | Additive vasodilatory effects | Do not combine — use only one PDE5 inhibitor at a time |
Moderate Interactions (Use with Caution)
| Drug / Drug Class | Effect | Recommendation |
|---|---|---|
| Alpha-blockers (doxazosin, tamsulosin, alfuzosin) | Risk of symptomatic hypotension (dizziness, fainting) | Stabilise on alpha-blocker first; use tadalafil with caution |
| CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, erythromycin, clarithromycin) | Increased tadalafil plasma levels and risk of side effects | Consider dose reduction; do not exceed 10 mg every 72 hours with potent inhibitors |
| CYP3A4 inducers (rifampicin, phenobarbital, phenytoin, carbamazepine) | Reduced tadalafil exposure and decreased effectiveness | Higher doses may be needed; consult your doctor |
| 5-alpha reductase inhibitors (finasteride, dutasteride) | Used concurrently for BPH; no significant pharmacokinetic interaction | Can be combined under medical supervision for BPH |
| Antihypertensives (various classes) | Additional blood pressure lowering effect | Monitor blood pressure; caution advised |
Food and Alcohol Interactions
Unlike some other PDE5 inhibitors, tadalafil’s absorption is not significantly affected by food intake. The tablet can be taken with or without meals, including high-fat meals, without any clinically meaningful delay in onset of action. This is a practical advantage for patients who prefer not to plan their meals around medication timing.
Regarding alcohol, moderate consumption does not produce a direct pharmacological interaction with tadalafil. However, both tadalafil and alcohol can independently lower blood pressure and cause vasodilation. Consuming excessive amounts of alcohol (resulting in a blood alcohol level of 0.08% or higher) while taking tadalafil may increase the risk of side effects such as dizziness, headache, rapid heart rate, and a drop in blood pressure upon standing (orthostatic hypotension). To optimise treatment outcomes and minimise adverse effects, it is advisable to limit alcohol intake when using tadalafil.
Grapefruit juice is a known inhibitor of CYP3A4 enzymes and may increase tadalafil plasma levels. While the clinical significance of this interaction is generally modest, patients should exercise caution with regular or large quantities of grapefruit juice. Consult your doctor if you regularly consume grapefruit products.
What Is the Correct Dosage of Tadalafil?
Quick Answer: Tadalafil offers two dosing strategies: once-daily (2.5–5 mg taken at the same time each day) or as-needed (10–20 mg taken before sexual activity). The once-daily regimen is suitable for men who have sex two or more times per week. Never take more than one dose per day.
Tadalafil should always be taken according to your doctor’s instructions. The dosing regimen will be individualised based on your medical condition, other medications you are taking, and how you respond to treatment. Tadalafil is unique among PDE5 inhibitors in offering two distinct dosing strategies, giving patients and their physicians greater flexibility in tailoring treatment to individual needs and lifestyles.
Once-Daily Dosing
Daily Low-Dose Regimen
- Recommended dose: 5 mg once daily, taken at approximately the same time each day
- Dose adjustment: Your doctor may reduce the dose to 2.5 mg daily based on your individual response and tolerability
- Maximum frequency: One tablet per day — do not exceed this
- Suitability: Men who anticipate sexual activity two or more times per week
- Onset: Continuous readiness for sexual activity at any time during the 24-hour period
The once-daily regimen provides a steady-state plasma concentration that allows for erectile readiness throughout the day, eliminating the need to plan dosing around sexual activity. This approach is particularly valued by men and their partners who prefer greater spontaneity. When taken daily, tadalafil reaches a steady-state concentration within approximately 5 days, after which the medication provides consistent effectiveness.
As-Needed Dosing
As-Needed (PRN) Regimen
- Starting dose: 10 mg, taken before anticipated sexual activity
- Dose adjustment: May be increased to 20 mg or decreased to 5 mg based on efficacy and tolerability
- Timing: Take at least 30 minutes before sexual activity; the drug remains effective for up to 36 hours
- Maximum frequency: Once per day — do not take more than one dose in any 24-hour period
| Patient Group | Daily Dose | As-Needed Dose | Notes |
|---|---|---|---|
| Healthy adults | 5 mg once daily | 10–20 mg | Choose regimen based on frequency of sexual activity |
| Elderly (≥65 years) | 2.5–5 mg | 10 mg (start low) | No routine dose adjustment solely for age |
| Hepatic impairment (mild–moderate) | Use with caution | 10 mg max | Severe hepatic impairment: not recommended |
| Renal impairment (severe) | 2.5 mg | 5–10 mg | Increased exposure; careful monitoring |
| On potent CYP3A4 inhibitors | 2.5 mg | 10 mg max (not more than every 72 h) | E.g. ketoconazole, ritonavir |
How to Take Tadalafil
Swallow the tablet whole with a glass of water. Do not crush, chew, or break the tablet. Tadalafil can be taken with or without food — unlike sildenafil, its absorption is not significantly affected by meals, including high-fat meals. For the daily regimen, take your tablet at approximately the same time each day to maintain consistent blood levels.
Children
Tadalafil for erectile dysfunction is not indicated for use in individuals under 18 years of age. It should not be given to children or adolescents for this purpose.
Elderly Patients
In elderly patients (65 years and older), no dose adjustment is routinely required based on age alone. However, elderly patients are more likely to have comorbid conditions and to be taking multiple medications, which may necessitate a lower starting dose or greater monitoring. Your doctor will take your overall health status and medication profile into account when determining the appropriate dose.
Missed Dose
If you are taking tadalafil on a daily schedule and miss a dose, take it as soon as you remember. However, do not take a double dose to compensate for the missed one. If it is almost time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. You should never take tadalafil more than once per day, regardless of the dosing regimen.
Overdose
If you have taken more tadalafil than prescribed, contact a doctor, hospital, or poison control centre immediately. Doses above the recommended maximum do not increase effectiveness but may increase the severity of side effects. Symptoms of overdose may include severe headache, dizziness, prolonged erection, fainting, and dangerously low blood pressure.
In the event of overdose, standard supportive care should be implemented. Tadalafil is highly bound to plasma proteins and is not significantly eliminated by haemodialysis. There is no specific antidote for tadalafil overdose.
What Are the Side Effects of Tadalafil?
Quick Answer: The most common side effects are headache, back pain, muscle pain, pain in the limbs, facial flushing, nasal congestion, and indigestion. Most are mild to moderate and resolve within hours. Serious but rare side effects include priapism, sudden vision loss, and sudden hearing loss.
Like all medicines, tadalafil can cause side effects, although not everyone will experience them. The adverse effects reported with tadalafil are generally mild to moderate in severity and are typically transient, resolving on their own without specific treatment. The side-effect profile of tadalafil differs somewhat from that of shorter-acting PDE5 inhibitors — notably, back pain and myalgia (muscle pain) are more frequently reported with tadalafil, while visual disturbances are less common than with sildenafil.
- Allergic reaction — skin rash, sudden wheezing, difficulty breathing, or swelling of the face, lips, or throat (uncommon)
- Chest pain — do NOT use nitrates to treat chest pain; seek emergency medical help immediately
- Prolonged erection (priapism) — an erection lasting continuously for more than 4 hours requires immediate emergency treatment to prevent permanent tissue damage (rare)
- Sudden vision loss — partial, temporary, or permanent loss of vision in one or both eyes, or distorted, dimmed, or blurred central vision (rare)
- Sudden hearing loss — decreased or lost hearing, with or without tinnitus or dizziness
Common
May affect up to 1 in 10 people
- Headache
- Back pain
- Muscle pain (myalgia)
- Pain in arms and legs
- Facial flushing (redness)
- Nasal congestion (stuffy nose)
- Indigestion (dyspepsia)
Uncommon
May affect up to 1 in 100 people
- Dizziness
- Stomach pain, nausea, vomiting
- Gastro-oesophageal reflux
- Blurred vision, eye pain
- Difficulty breathing (dyspnoea)
- Blood in urine (haematuria)
- Prolonged erection
- Palpitations, rapid heart rate (tachycardia)
- High blood pressure, low blood pressure
- Nosebleeds (epistaxis)
- Tinnitus (ringing in the ears)
- Swollen hands, feet, or ankles (peripheral oedema)
- Fatigue
- Allergic reactions with skin rash
Rare
May affect up to 1 in 1,000 people
- Fainting (syncope)
- Seizures
- Transient memory loss
- Swollen eyelids, red eyes
- Sudden hearing loss or decrease
- Skin rash with itchy red bumps (urticaria)
- Penile bleeding, blood in semen (haematospermia)
- Increased sweating
Not Known / Post-Marketing Reports
Frequency cannot be estimated from available data
- Distorted, dimmed, or blurred central vision; sudden visual impairment
- Migraine
- Facial swelling
- Severe allergic reaction (angioedema) with swelling of face and throat
- Severe skin reactions (Stevens-Johnson syndrome, exfoliative dermatitis)
- Irregular heartbeat (arrhythmia)
- Angina pectoris (chest pain)
- Sudden cardiac death
Dizziness has been reported more frequently in men over 75 years of age taking tadalafil. Diarrhoea has been reported more frequently in men over 65 years. Heart attack and stroke have been reported rarely in men taking tadalafil, but most of these patients had pre-existing cardiovascular risk factors. A direct causal relationship with tadalafil has not been definitively established.
If you experience any side effects not listed above, or if any side effects become severe, persistent, or bothersome, consult your doctor or pharmacist. Reporting suspected adverse reactions after a medicine has been authorised is important, as it allows continued monitoring of the benefit–risk balance.
How Should You Store Tadalafil?
Quick Answer: Store tadalafil at room temperature (below 30°C / 86°F) in the original packaging to protect from moisture. Keep out of the reach and sight of children. Do not use after the expiry date.
Proper storage of tadalafil ensures the medication remains safe and effective throughout its shelf life. Tadalafil tablets should be stored at a temperature not exceeding 30°C (86°F). Keep the tablets in the original packaging (blister pack or bottle) to protect them from moisture, as the formulation is moisture-sensitive.
As with all medications, keep tadalafil out of the sight and reach of children. Accidental ingestion by a child can cause serious adverse effects and should be treated as a medical emergency. Do not use tadalafil after the expiry date printed on the carton and blister pack — the expiry date refers to the last day of the stated month.
Do not dispose of medications via wastewater or household waste. Return unused or expired tablets to your pharmacy for safe disposal. Proper disposal helps protect the environment and prevents accidental exposure to other individuals or animals.
What Does Tadalafil Contain?
Quick Answer: Each tablet contains tadalafil as the active ingredient, along with pharmaceutical excipients including lactose monohydrate. Tablets are film-coated and available in 2.5 mg, 5 mg, and 20 mg strengths.
The active substance in tadalafil tablets is tadalafil itself, available in strengths of 2.5 mg, 5 mg, and 20 mg. The inactive ingredients (excipients) serve to form the tablet structure, aid in absorption, and provide the protective film coating. While the exact excipient composition may vary slightly between manufacturers, common inactive ingredients include:
- Tablet core: Lactose monohydrate, croscarmellose sodium, hydroxypropylcellulose, microcrystalline cellulose, sodium lauryl sulfate, magnesium stearate
- Film coating: Lactose monohydrate, hypromellose, triacetin, titanium dioxide (E171), yellow iron oxide (E172), red iron oxide (E172), talc
Tadalafil tablets contain lactose monohydrate. If your doctor has confirmed that you have an intolerance to certain sugars, contact your doctor before taking this medicine.
Tadalafil tablets contain less than 1 mmol (23 mg) of sodium per tablet, meaning they are essentially sodium-free. This is relevant for patients on a controlled sodium diet.
The branded version (Cialis) in the 2.5 mg strength is a light orange-yellow, almond-shaped, film-coated tablet marked with “C 2½” on one side. Generic formulations may differ in appearance but contain the same active ingredient at equivalent strengths. Tablets are typically supplied in blister packs of 28 tablets (for daily dosing) or smaller pack sizes for as-needed use.
Frequently Asked Questions About Tadalafil
Tadalafil has a remarkably long duration of action compared to other erectile dysfunction medications. A single dose can remain effective for up to 36 hours, which is why it is sometimes called “the weekend pill.” This does not mean you will have a continuous erection for 36 hours — sexual stimulation is still required for the medication to work. The long duration allows for significantly greater spontaneity in sexual activity, as there is less need to plan the timing of the dose precisely. When taken daily at the low dose (2.5–5 mg), tadalafil provides continuous readiness.
Yes, tadalafil is the only PDE5 inhibitor approved for once-daily use at a low dose. The daily regimen uses 2.5 mg or 5 mg, taken at the same time each day regardless of planned sexual activity. This approach is generally recommended for men who have sex two or more times per week. After approximately 5 days of daily dosing, tadalafil reaches steady-state levels in the blood, providing continuous readiness for an erection whenever sexual stimulation occurs. Your doctor can advise whether the daily or as-needed regimen is most appropriate for your situation.
Both tadalafil and sildenafil are PDE5 inhibitors used to treat erectile dysfunction, but they differ in several important ways. Tadalafil lasts up to 36 hours compared to sildenafil’s 4–6 hours. Tadalafil can be taken daily at a low dose, while sildenafil is only approved for as-needed use. Tadalafil’s absorption is not affected by food, whereas a high-fat meal can delay sildenafil’s onset. Tadalafil is more associated with back pain and muscle pain as side effects, while sildenafil is more likely to cause visual disturbances and facial flushing. The choice between the two depends on individual lifestyle, frequency of sexual activity, and how you respond to each medication.
Moderate alcohol consumption is generally compatible with tadalafil use and does not create a significant pharmacological interaction. However, excessive alcohol (blood alcohol level of 0.08% or more) should be avoided, as both alcohol and tadalafil lower blood pressure. Combining them in excess can increase the risk of dizziness, headache, rapid heart rate, and drops in blood pressure when standing. To achieve the best results and minimise side effects, keep alcohol intake moderate when taking tadalafil.
Tadalafil is contraindicated for men with severe heart disease, those who have had a heart attack within the last 90 days, and those taking nitrate medications. However, many men with stable, well-managed cardiovascular disease can safely use tadalafil under their doctor’s supervision. The primary safety concern is that sexual activity itself places additional demand on the heart, so your doctor must assess whether your cardiovascular status permits this. Never combine tadalafil with nitrates or nitric oxide donors, as this can cause a dangerous, potentially fatal drop in blood pressure.
In both animal studies and some clinical observations, a decrease in sperm count has been noted with tadalafil use. However, this reduction is generally considered unlikely to lead to infertility in most men. The effect on sperm parameters appears to be reversible after stopping the medication. If you are actively trying to conceive or have concerns about your reproductive health, discuss this with your doctor before starting tadalafil. Your doctor can weigh the benefits of treatment against any potential effects on fertility.
References and Sources
This article is based on the following peer-reviewed sources and authoritative medical guidelines:
- European Medicines Agency (EMA). Summary of Product Characteristics — Tadalafil (Cialis). EMA Product Information. Updated 2025.
- U.S. Food and Drug Administration (FDA). Prescribing Information for Tadalafil Tablets. FDA Drug Labeling. 2024.
- World Health Organization (WHO). WHO Model List of Essential Medicines — 23rd List, 2023. Geneva: WHO; 2023.
- British National Formulary (BNF). Tadalafil monograph. NICE BNF. Accessed January 2026.
- Brock GB, McMahon CG, Chen KK, et al. Efficacy and safety of tadalafil for the treatment of erectile dysfunction: results of integrated analyses. J Urol. 2002;168(4 Pt 1):1332-1336. doi:10.1016/S0022-5347(05)64443-2
- Hatzimouratidis K, Giuliano F, Moncada I, et al. EAU Guidelines on Erectile Dysfunction. European Association of Urology. 2024.
- Burnett AL, Nehra A, Breau RH, et al. Erectile Dysfunction: AUA Guideline. J Urol. 2018;200(3):633-641. doi:10.1016/j.juro.2018.05.004
- Forgue ST, Patterson BE, Bedding AW, et al. Tadalafil pharmacokinetics in healthy subjects. Br J Clin Pharmacol. 2006;61(3):280-288. doi:10.1111/j.1365-2125.2005.02599.x
- McMahon CG. Current diagnosis and management of erectile dysfunction. Med J Aust. 2019;210(10):469-476. doi:10.5694/mja2.50167
- Kloner RA. Cardiovascular effects of the 3 phosphodiesterase-5 inhibitors approved for the treatment of erectile dysfunction. Circulation. 2004;110(19):3149-3155.
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