Tadalafil Dosage Guide: Strengths, Daily vs. As-Needed, and Timing

Last reviewed July 9, 2026 by Dr. Michael Rio, PharmD, a licensed pharmacist.

Tadalafil dosing is more structured than it might appear from casual conversation about it. FDA-approved labeling lays out specific strengths, two distinct dosing patterns, and clear maximum-dose guidance. This page summarizes that structure. It is not a substitute for the specific instructions a prescriber gives, which take into account kidney and liver function, other medicines, and the reason tadalafil is being used.

Approved Strengths

Daily Dosing vs. As-Needed Dosing

These are two distinct, both FDA-approved, ways of using tadalafil, and they are not interchangeable without a prescriber's input:

• Daily dosing (2.5mg or 5mg): taken at roughly the same time each day, maintaining a steady low level of the medicine. This pattern removes the need to time a dose around a specific moment and is also the pattern used for BPH symptom management.
• As-needed dosing (10mg or 20mg): taken before anticipated use, generally not more than once in a 24-hour period. Prescribers often start at the lower as-needed strength and adjust based on response and tolerability.

Which pattern fits better depends on frequency of use, cost considerations, side-effect tolerance, and other health factors — a conversation for a prescriber, since switching between patterns isn't simply a matter of personal preference in isolation.

Timing Considerations

For as-needed dosing, labeling describes an onset window of roughly 30 minutes to 2 hours, with effects that can persist up to 36 hours. Unlike sildenafil, food has a minimal effect on tadalafil absorption, which is one reason it's sometimes chosen by people who find meal-timing restrictions inconvenient with other options. Alcohol in significant amounts can still affect blood pressure regardless of which PDE5 inhibitor is used, so labeling generally advises moderation.

Maximum Dose Guidance

FDA labeling caps as-needed dosing at 20mg once daily maximum and daily dosing at 5mg once daily maximum under standard kidney and liver function. Reduced doses are specified in labeling for people with kidney impairment or those taking certain other medicines (particularly alpha-blockers or CYP3A4 inhibitors), which is exactly the kind of detail a prescriber checks against an individual's chart before prescribing. Taking more than the labeled maximum does not have established additional benefit and increases the likelihood of side effects.

Missed or Adjusted Doses

For daily dosing, labeling generally advises simply resuming the normal schedule rather than doubling up if a dose is missed. For as-needed dosing, there's no "schedule" to miss — it's taken only when needed, within the maximum-frequency guidance above. Any adjustment to dose or frequency outside of labeling should go through a prescriber rather than be self-directed.

Sources and Further Reading

• DailyMed (National Library of Medicine) — official prescribing information and dosing tables.
• U.S. Food and Drug Administration — Drugs — regulatory background on approved dosing.