It works in most of the cases if the cause of your hair fall is indeed androgenic alopecia / male pattern baldness, which is common in men. Read up more on minoxidil and the types of baldness it can treat.
Its effects still vary from person to person; from very less hair restoration to excellent! The most important thing to realize is that you won't get instant results, rather you will have to wait at least 1/2 months to see any significant improvement.
This drug like many others is also not without side effects so always keep that in mind and do a search on its side effects.
Hair fall will start again if you discontinue its use.