In men, hair loss usually initially involves the front and sides of the scalp and progresses towards the back of the head. By 30 years of age, it affects about a third of white men. This increases to around 80% in men older than 70 years of age.

Hair loss progresses over time in untreated men. The rate of progression is unpredictable and some men eventually lose almost all of the scalp hairs, while others retain a considerable number particularly in the occipital and parietal areas above the ears.

Treatment needs to be taken indefinitely to maintain any effect.

Most men find that their hair loss improves after 4 to 6 months of treatment. The effect of finasteride on the scalp will only last as long as the medicine is taken. When it is stopped the hair will begin to be lost. Finasteride is a once daily tablet.