Is 25 mg a failure badge?
No. The label treats 25 mg as the right first number when those flags sit on the chart. Shame about the 'low' tablet is a review contaminant. Step-up after a clean 25 mg trial lives on the dose ladder.
Site lock on 25-100 mg remains the sildenafil panel. 25 mg is one rung of that range, not a different drug.
What hepatic line sits next to 25 mg?
Hepatic impairment, for example cirrhosis. The label groups that flag with age and severe renal impairment in the same consider-25 sentence.
Men who drink more than they admit can hide this flag. If liver enzymes are a live issue, stay on the low rung until someone reviews them.
What renal number pulls the start down?
Creatinine clearance under 30 mL/min. Severe renal impairment raises exposure. The labeled move is to consider 25 mg, not to invent a new ED strength.
CrCl 50-80 is not that sentence. Do not drag every reduced eGFR into the under-30 bucket.
What if an alpha-blocker is already stable?
Start sildenafil at 25 mg, and only after the alpha-blocker is stable. Both classes drop blood pressure. Symptomatic hypotension can still occur. Full room: the alpha-blocker scan.
'I have taken tamsulosin for years' is not a 50 mg passport.
Does age 65 alone change the first tablet?
Consider 25 mg. Adults 65 and older showed about 84% higher sildenafil AUC than younger volunteers. The label does not ban 50 mg in that group. It asks the writer to think 25 mg first.
Skipping 25 mg because a forum 'rates' 50 as standard is how first nights get ugly. Trial safety looked similar across age bands overall. The PK bump is still real.
Which CYP drugs pull the start to 25 mg?
Erythromycin and strong CYP3A4 inhibitors such as ketoconazole, itraconazole, or saquinavir. Clinical data put saquinavir or erythromycin at about a 3-fold rise in sildenafil levels. Erythromycin specifically raised Cmax about 160% and AUC about 182%.
Ritonavir is the extreme: about 11-fold, 25 mg, no repeat in 48 hours. Keep that on the ritonavir scan.