A male patient taking tadalafil (Cialis) 20 mg as needed cannot maintain an erection long enough for satisfactory intercourse; how should his therapy be adjusted?

Management of Inadequate Response to Tadalafil 20 mg

For a patient taking tadalafil 20 mg who cannot maintain an erection, the first critical step is to verify he has completed an adequate trial—defined as at least 5 separate attempts at this maximum dose with proper technique, adequate sexual stimulation, correct timing, and absence of modifiable factors like heavy alcohol use—before declaring treatment failure. 1

Immediate Assessment: Rule Out Common Causes of Apparent Treatment Failure

Before escalating or switching therapy, systematically evaluate these modifiable factors that account for up to 30% of apparent non-responders 1:

• Verify adequate sexual stimulation is occurring—PDE5 inhibitors require sexual arousal to work; the medication will not produce an erection without it 1, 2
• Assess timing of medication—tadalafil should be taken at least 30 minutes before anticipated sexual activity, though it remains effective up to 36 hours 2
• Check for heavy alcohol consumption—substantial alcohol intake (≥5 units) impairs erectile function independent of medication and increases risk of orthostatic hypotension 1, 2
• Evaluate for large or fatty meals—taking tadalafil with substantial food can reduce efficacy 1
• Screen for relationship issues or psychological factors—depression, anxiety, and partner conflict significantly impact treatment response 1

Critical Hormonal Evaluation

Check testosterone levels (total testosterone, free testosterone, and SHBG) before declaring PDE5 inhibitor failure, as men with testosterone deficiency respond less robustly to tadalafil alone. 1

• The 2025 European Association of Urology guidelines recommend combining PDE5 inhibitors with testosterone therapy in more severe forms of ED, particularly in hypogonadal men 3
• Testosterone therapy alone is not effective monotherapy for ED, but combination therapy with tadalafil may be more effective than tadalafil alone in men with confirmed hypogonadism 1
• Men with diabetes or post-prostatectomy have more severe ED at baseline and may respond less robustly to PDE5 inhibitors, making hormonal assessment particularly important in these populations 1

Medication Review

Identify drugs that worsen erectile dysfunction 1:

• Antihypertensives (especially thiazide diuretics, beta-blockers)
• Antidepressants (SSRIs, SNRIs)
• Opioids
• Hormone therapy
• Verify no nitrate use in any form—this is an absolute contraindication 1, 2

Treatment Adjustment Algorithm

If Adequate Trial Not Yet Completed:

• Continue tadalafil 20 mg with proper technique for at least 5 separate attempts 1
• Address all modifiable factors identified above 1

If Adequate Trial Completed and Well-Tolerated:

Consider switching to daily tadalafil 5 mg rather than continuing as-needed dosing. 2, 4

• A 2014 study demonstrated that 39-40% of men who failed to achieve normal erectile function (IIEF-EF ≥26) with maximum-dose as-needed PDE5 inhibitors returned to normal function when switched to daily tadalafil, compared to only 12% with placebo 4
• Daily dosing eliminates the need to time medication with sexual activity and may provide superior efficacy in men with incomplete response to as-needed therapy 1, 4
• The FDA-approved dose for daily use is 2.5-5 mg taken at approximately the same time every day 2

If Hormonal Deficiency Identified:

• Combine tadalafil with testosterone therapy rather than continuing tadalafil alone 3, 1
• The 2025 EAU guidelines specifically recommend this combination approach for more severe ED 3

If Two Different PDE5 Inhibitors Fail at Maximum Dose:

Only after failure of at least two different PDE5 inhibitors with proper technique should you proceed to second-line therapies 1:

• Vacuum erection devices
• Intraurethral alprostadil suppositories
• Intracavernosal injection therapy
• Penile prosthesis implantation (for refractory cases)

Critical Safety Reminder

Tadalafil remains contraindicated with any form of nitrate use due to risk of life-threatening hypotension. 1, 2 If emergency nitrates are needed, wait 48 hours after the last tadalafil dose before administering nitrates under close medical supervision 1

Common Pitfall to Avoid

The most critical error is declaring treatment failure without completing an adequate trial of at least 5 separate attempts at maximum dose with proper technique 1. Many apparent failures are actually due to incorrect use—lack of sexual stimulation, improper timing, or taking medication with large meals—rather than true medication inefficacy 1.