Topical Finasteride 2,5% - Dosage: 1ml every other day, or 0.5ml daily?

By reducing your dose, you will reduce the effectiveness. However, this requires an in-person evaluation. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

At 2.5% of finasteride, more likely than not you will have systemic absorption of it. This negates the benefit of using finasteride topically to reduce its systemic side effects. Typical concentrations to avoid systemic absorption range between .5-1%, and the solutions can be combined with higher percentage of minoxidil to increase its efficacy.

Be aware that by reducing the dose you're also reducing the effectiveness of the drug- it would be best to go over it with your doctor. But, there's not really much literature about topical Finasteride out there. I suspect using 0.5ml daily would be better but there's little research that could confirm or deny this.