01Why is stimulation still required after the hour?
Sexual stimulation is required for a response. The tablet does not start an erection while you wait in a chair. Nitric oxide still has to be released locally from nerve endings and endothelium before cGMP can rise. PDE5 inhibition holds that cGMP; it does not start the nitric oxide pulse.
If the hour passed and nothing was attempted, the quiet hour is not a failed dose. It is a dose that never got its trigger. PDE5 inhibition has nothing to hold until that nitric oxide pulse shows up. Alcohol that blunts the attempt is a different page.
02Where does the 2.5 mg tablet belong if you are asking about speed?
It belongs on the strength list, next to 5, 10, and 20 mg. Strong CYP3A4 inhibitors are one reason a 2.5 mg tablet exists. Speed of onset is not that reason. Ritonavir is the inhibitor that also stretches the gap to 72 hours. Erythromycin uses a 5 mg ceiling, not a faster 2.5 mg.
Do not treat 2.5 mg as a quicker starter. Treat it as a lower dose when the chart needs one. Indinavir, ketoconazole 400 mg daily, and itraconazole 400 mg daily use that same 2.5 mg ceiling inside 24 hours.
03Why does the start line say about 60 minutes?
For most patients the recommended start is 10 mg, taken orally about 60 minutes before sexual activity. That hour is the counselling line, not a stopwatch you fail if minute 45 is quiet. Absolute bioavailability is about 15%, so a lot of the swallow never reaches plasma. The 2.5 mg tablet is not a faster route around that 15%.
The maximum recommended frequency is once per day. A second swallow in the same day does not speed the first hour. It also does not raise that 15% figure.
04When does a 20 mg tablet actually peak?
After a single 20 mg dose in healthy men, peak plasma levels usually land between 30 minutes and 2 hours. The median in the fasted studies was 60 minutes. That is why the start counselling and the 20 mg Tmax window sit near the same hour. A high-fat meal can push that rise later; the Tmax span already starts wide when fasted. Sexual stimulation still has to land inside that span.
Two-point-five milligrams is one of the four tablet strengths. It is not a faster onset. It is a lower amount on the same ladder.
05The first hour felt like nothing. Can you take another tablet?
No. Once per day is the cap. A quiet hour is a reason to talk about timing, food, or whether 10 mg is the right start - not a reason to stack a second film-coated tablet. Chewing the first tablet is also not a labelled speed trick. Absolute bioavailability stays about 15% after either swallow.
The vardenafil shelf keeps that once-a-day line next to the 10 mg start. Stimulation still has to happen inside that hour if you want a read.
06Do you have to wait for an empty stomach?
A meal is allowed on the start line. High fat can delay onset. Food and Levitra is the page for that delay. This room only needs the optional swallow. The US food-effect studies cut Cmax by 18% to 50% on high-fat meals.
A light plate does not rewrite the 60-minute counselling line. Fasted Tmax after 20 mg already spans 30 minutes to 2 hours, so a heavy plate sits on top of a wide window. Do not stack a second tablet to chase a delayed rise.