Cialis (Tadalafil) Dosage for Erectile Dysfunction
For as-needed use, start with tadalafil 10 mg taken prior to sexual activity, with dose adjustment to 20 mg or 5 mg based on response; for daily use, start with 2.5 mg once daily and increase to 5 mg if needed. 1
As-Needed Dosing (On-Demand)
Starting dose: 10 mg taken before anticipated sexual activity 1
Dose adjustment:
- Increase to 20 mg if 10 mg provides insufficient response 1
- Decrease to 5 mg if side effects are problematic 1
- Maximum dosing frequency is once per day 1
Key advantage: Tadalafil remains effective for up to 36 hours after dosing, allowing flexibility in timing of sexual activity 1, 2. Most patients take advantage of this extended window, with over 79% attempting intercourse between 4-36 hours after dosing and 53% attempting intercourse between 12-36 hours post-dose 2. The medication can produce erectogenic effects as early as 16 minutes after taking the 20 mg dose 3.
Once-Daily Dosing
Starting dose: 2.5 mg taken at approximately the same time every day 1
Dose adjustment: Increase to 5 mg daily based on efficacy and tolerability 1
Key advantage: Daily dosing eliminates the need to time medication with sexual activity, providing spontaneity for couples who prefer unscheduled intimacy 4. Both 5 mg and 10 mg daily doses significantly improve erectile function, with 84-85% of patients reporting improved erections 5. Long-term daily use of 5 mg has been shown to be safe and effective for up to 2 years 6.
Dose Adjustments for Special Populations
Renal impairment:
- Creatinine clearance 30-50 mL/min (as-needed): Start with 5 mg, maximum 10 mg once every 48 hours 1
- Creatinine clearance <30 mL/min or hemodialysis (as-needed): Maximum 5 mg once every 72 hours 1
- Creatinine clearance <30 mL/min (daily dosing): Not recommended 1
Hepatic impairment:
- Mild to moderate (Child-Pugh A or B): Maximum 10 mg once daily for as-needed use; use caution with daily dosing 1
- Severe (Child-Pugh C): Not recommended 1
Important Clinical Considerations
Efficacy profile: Unlike sildenafil and vardenafil, tadalafil does not show dose-dependent improvement in erectile function between 5-20 mg doses 4. This means that 5 mg may be as effective as higher doses for many patients, making it a reasonable starting point to minimize side effects.
Treatment trial adequacy: An adequate trial consists of at least 5 separate attempts at maximum dose before declaring treatment failure 4. If tadalafil fails, consider switching to a different PDE5 inhibitor rather than abandoning this class of medications 4.
Patient education is critical: Sexual stimulation is necessary for the medication to work, and incorrect use accounts for many treatment failures 4, 7. Patients must understand this is not an automatic erection pill.
Common adverse effects: Dyspepsia, headache, back pain, nasal congestion, and myalgia 4. Tadalafil has lower rates of flushing compared to other PDE5 inhibitors 4.
Absolute contraindication: Never prescribe with nitrates in any form due to risk of potentially fatal hypotension 4, 1. Explicitly ask about all forms of nitrate use before prescribing.
Cardiovascular screening: Assess whether the patient can perform moderate physical activity equivalent to walking 1 mile in 20 minutes or climbing 2 flights of stairs; refer to cardiology if unable 8, 4.
Combination Therapy
For men with both ED and testosterone deficiency, combining tadalafil with testosterone therapy may be more effective than tadalafil alone 4. However, testosterone alone is not effective monotherapy for ED 4.