Can a patient take tadalafil 5 mg daily and also take an additional dose on an as‑needed (prn) basis?

No, Do Not Combine Daily Tadalafil 5 mg with Additional As-Needed Doses

You should not take tadalafil 5 mg daily and then add extra doses on an as-needed basis. The FDA labeling explicitly states that the maximum recommended dosing frequency for tadalafil is once per day in most patients 1. This applies regardless of whether you're using the daily or as-needed regimen—you cannot safely combine both approaches.

Why This Matters

The FDA-approved dosing strategies for tadalafil are mutually exclusive:

• Daily dosing: 2.5-5 mg taken at the same time every day, regardless of sexual activity timing 1
• As-needed dosing: 5-20 mg taken prior to anticipated sexual activity, maximum once per day 1

These are separate treatment strategies—not complementary ones. Combining them would exceed the maximum recommended daily dose and increase the risk of adverse events including hypotension, headache, dyspepsia, back pain, and myalgia 2.

The Evidence on Daily vs As-Needed Dosing

Research demonstrates that both regimens provide comparable efficacy:

• Daily tadalafil 5 mg produces similar erectile function improvements as as-needed dosing in head-to-head comparisons 3
• Men who had incomplete responses to as-needed PDE5 inhibitors (including tadalafil 20 mg) achieved normal erectile function (IIEF-EF ≥26) in 39-40% of cases when switched to daily tadalafil 5 mg, compared to only 12% with placebo 4
• The 2018 AUA guideline confirms that "on-demand dosing versus daily dosing for tadalafil appears to produce the same level of efficacy" 2

What to Do Instead

If you're currently on daily tadalafil 5 mg and finding it insufficient:

1. First, ensure you've been on the daily regimen long enough (at least 4-12 weeks) to achieve steady-state therapeutic levels and maximal benefit 5, 6

2. If inadequate response persists after adequate trial, consider switching strategies entirely:

   • Switch to as-needed tadalafil: Use 10-20 mg taken prior to sexual activity (not in addition to daily dosing) 1
   • Optimize the daily regimen: Ensure you're taking it consistently at the same time each day 1

3. Discuss with your prescriber whether the daily or as-needed approach better fits your sexual activity patterns and treatment goals

Key Safety Considerations

• Never exceed one dose per 24 hours regardless of formulation or indication 1
• The long half-life of tadalafil (17.5 hours) means therapeutic levels persist well beyond a single day with daily dosing 5
• Patients with renal impairment (CrCl 30-50 mL/min) should use even lower doses and longer intervals between doses 1

The Bottom Line

Choose one strategy or the other—daily or as-needed—but never combine them. The FDA labeling is unambiguous on this point, and violating this guidance increases your risk of adverse events without evidence of additional benefit. If your current regimen isn't working, the solution is to switch strategies entirely, not to stack doses.