Last reviewed 2026-04-23 · How we verify

placebo (tadalafil)

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor, which works by increasing blood flow to the penis to treat erectile dysfunction.

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor, which works by increasing blood flow to the penis to treat erectile dysfunction. Used for Erectile dysfunction.

At a glance

Mechanism of action

PDE5 inhibitors like tadalafil block the action of phosphodiesterase type 5, an enzyme that breaks down cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the corpus cavernosum. This leads to increased levels of cGMP, causing smooth muscle relaxation and increased blood flow to the penis, resulting in an erection. Tadalafil is a potent and selective inhibitor of PDE5, with a long half-life that allows for once-daily dosing.

Approved indications

• Erectile dysfunction

Common side effects

• Headache
• Back pain
• Muscle pain
• Nausea
• Flushing

Key clinical trials

• Tadalafil 5 mg on Storage Lower Urinary Tract Symptoms After Anatomical Endoscopic Enucleation of the Prostate (PHASE1)
• Double j Stent Related Symptoms (EARLY_PHASE1)
• Trial of Tadalafil, Tamsulosin and Combination for Access Sheath Deployment (PHASE4)
• Breathe Easier With Tadalafil Therapy for Dyspnea in COPD-PH (PHASE2)
• Daily Tadalafil 5 mg Combined With On-Demand Sildenafil 100 mg for Treatment of Erectile Dysfunction in PDE-5I Non Responder Patients (PHASE4)
• The Effects of Mirabegron and Tadalafil on Glucose Tolerance in Prediabetics (PHASE4)
• Tadalafil for Severe Pulmonary Hypertension Due to Chronic Obstructive Pulmonary Disease (PHASE3)
• Clinical Study to Compare the Efficacy and Safety of Macitentan and Tadalafil Monotherapies With the Corresponding Fixed-dose Combination Therapy in Subjects With Pulmonary Arterial Hypertension (PAH) (PHASE3)

Primary sources

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