Finasteride (Propecia) works as part of the natural cycle of shedding and growth of hair, which means that it takes approximately 3-to-6 months for a visible difference to show. Baby hairs and some change may appear before this but, for the majority of men, the maximum effect will be achieved in around 12 months.
Patients taking Minoxidil (Rogaine) should expect to wait between 3-to-6 months to notice visible results. A study by the FDA found that after 4 months 26% of patients had moderate to dense regrowth, with a further 33% showing some regrowth too. Another study into Minoxidil didn’t find much change at 3 months, but reported significant effects after 6 months of continuous use.
Dutasteride (Avodart) generally takes up to 12 months or more to show significant effects in both preventing hair loss and in re-growing hair. But patients report that between 3-6 months on dutasteride, reversing results of early stages of hair loss created by thinning hair, bald spots and receding hairlines, could be noticed.
* Results may vary