Much confusion surrounds the difference between topical hair loss products (applied directly to the scalp) and internal products (taken by mouth). They both can be effective in managing hair loss but are NOT equivalent when trying to block the male hormone DHT.
DHT is produced in both hair follicle and the liver. If a topical product is aimed at the scalp hair follicle it will likely be less effective than oral blocking as the liver supplies DHT directly to the follicle via the blood. This is why finasteride needs to be taken orally to give the best effect.
In men with male pattern balding the oral use of blockers (e.g. finasteride) has proven to be far superior to the use of topical stimulants (e.g. minoxidil or laser). That said they can be successfully used together to produce even better results as they act in different areas.
For male pattern balding, effective therapy begins with a medical doctor