What is the standard dose of tadalafil (Cialis) for erectile dysfunction (ED) in adult males?

Standard Tadalafil Dosing for Erectile Dysfunction

For as-needed use, start with tadalafil 10 mg taken prior to anticipated sexual activity, which can be titrated to 20 mg or decreased to 5 mg based on response and tolerability; for daily use, start with 2.5 mg once daily and increase to 5 mg if needed. 1

As-Needed Dosing (On-Demand)

• The FDA-approved starting dose is 10 mg taken before sexual activity, with dose adjustment to 20 mg (maximum) or 5 mg based on individual efficacy and tolerability 1
• Maximum dosing frequency is once per day in most patients 1
• Tadalafil remains effective for up to 36 hours after dosing, allowing for spontaneous sexual activity without precise timing 2, 1
• Importantly, tadalafil does NOT show dose-dependent improvement in erectile function between 5 mg, 10 mg, and 20 mg doses—meaning the choice between doses should be based primarily on tolerability rather than expecting dramatically better efficacy at higher doses 2

Defining Treatment Success vs. Failure

• An adequate trial requires at least 5 separate attempts at maximum tolerated dose before declaring treatment failure 2
• High-quality evidence shows 69% of men using as-needed tadalafil report successful sexual intercourse attempts compared to 33% with placebo 2
• Before switching therapies, systematically evaluate modifiable factors: hormonal abnormalities, food/drug interactions, timing and frequency of dosing, adequacy of sexual stimulation, heavy alcohol use, and relationship issues 2

Once-Daily Dosing

• The FDA-approved starting dose for daily use is 2.5 mg taken at approximately the same time every day, without regard to timing of sexual activity 1
• The dose may be increased to 5 mg once daily based on individual efficacy and tolerability 1
• Daily dosing eliminates the need to time medication with sexual activity entirely, providing an alternative for couples who prefer spontaneous rather than scheduled sexual activity 2
• Research suggests daily dosing may provide superior outcomes compared to on-demand dosing, with better IIEF-5 scores at 8 weeks (21.6 vs 18.5) and sustained improvement 1 month after withdrawal 3
• Long-term studies demonstrate that tadalafil 5 mg once daily is safe and well-tolerated for up to 2 years, with 95.7% of patients reporting improved erections 4

Critical Safety Verification Before Prescribing

• Tadalafil is absolutely contraindicated in patients taking oral nitrates in any form due to risk of potentially fatal hypotension 2
• Assess cardiovascular fitness by asking if the patient can walk 1 mile in 20 minutes or climb 2 flights of stairs without symptoms—if unable, refer to cardiology before prescribing 2
• Most ED patients are low-risk and can safely receive tadalafil, including those with asymptomatic coronary artery disease with <3 risk factors, controlled hypertension, mild stable angina, successful coronary revascularization, uncomplicated past MI, mild valvular disease, and CHF (NYHA class I) 2
• High-risk patients should defer treatment: unstable angina, uncontrolled hypertension, recent MI (within 2 weeks), NYHA Class III-IV heart failure, or severe valvular disease 2

Dose Adjustments for Renal Impairment

For As-Needed Use:

• Creatinine clearance 30-50 mL/min: Start with 5 mg, maximum 10 mg once every 48 hours 1
• Creatinine clearance <30 mL/min or hemodialysis: Maximum 5 mg once every 72 hours 1

For Once-Daily Use:

• Creatinine clearance 30-50 mL/min: Start with 2.5 mg, may increase to 5 mg based on response 1
• Creatinine clearance <30 mL/min or hemodialysis: Once-daily use is not recommended 1

Dose Adjustments for Hepatic Impairment

• Mild or moderate hepatic impairment (Child-Pugh Class A or B): Maximum dose 10 mg once per day for as-needed use 1
• Once-daily use has not been extensively evaluated in hepatic impairment—use with caution 1
• Severe hepatic impairment: PDE5 inhibitors are generally not recommended 2

Common Adverse Effects and Management

• Most common adverse events include dyspepsia (11.8%), headache (15.8%), back pain (8.2%), nasal congestion, and myalgia 2, 5
• Tadalafil has lower rates of flushing compared to other PDE5 inhibitors 2
• Discontinuation rate due to adverse events in long-term studies is only 6.3%, with <1% for any individual event 5
• Titrate doses to find the optimal balance between efficacy and side effects—since efficacy is not dose-dependent, lower doses may provide equal benefit with fewer adverse effects 2

Special Populations

• Men with diabetes respond well to tadalafil, though baseline ED severity may be greater—treatment significantly improves erectile function regardless of baseline HbA1c level 6
• Post-prostatectomy patients have more severe ED at baseline and may respond less robustly, but tadalafil remains effective 2
• For men with both ED and testosterone deficiency, combining tadalafil with testosterone therapy may be more effective than tadalafil alone 2
• Testosterone therapy alone is not effective monotherapy for ED 2

Emergency Nitrate Protocol

• If a patient on tadalafil requires emergency nitrate administration, wait 48 hours after the last tadalafil dose before giving nitrates, under close medical supervision with patient monitoring 2
• This is longer than the 24-hour wait required for sildenafil due to tadalafil's extended half-life 2

Patient Counseling Points

• Sexual stimulation is necessary for tadalafil to be effective—incorrect use accounts for a large percentage of treatment failures 2
• Tadalafil may be taken without regard to food 1
• Do not split tablets; the entire dose should be taken 1
• Avoid heavy alcohol use, as it may impair erectile function and increase risk of adverse effects 2