Is splitting finasteride 5mg bad? Will it ruin the effectiveness?

We tell patients that the most cost-effective way of taking finasteride is to split the 5 mg tablet in half and take half a pill every other day (Monday, Wednesday, Friday).

It would depend on how well you split the tablet. I suggest seeing a hair loss expert now to evaluate and go over your condition and test results and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone which work well with Finasteride. Hair transplantation is an alternative. See an expert. Best, Dr. Emer

I am going to assume you have already had your in-person consultation with a hair restoration expert and that finasteride was prescribed to help you maintain your thinning hair.  The reality of pharmacy pricing is that pill splitting is accepted and common.  For years, older Americans have done so to save on drug prices.  There is a reason that pill splitters are so common in drugstores.  So the short answer: it is fine.