Finasteride

One of the main factors involved in male-pattern hair loss is the activity of DHT (dihydrotestosterone) on the hair follicles. When present, DHT activates a receptor in the hair follicle which causes the growth phase of the hair to gradually decrease, and shrinks the follicle resulting in finer, shorter hairs until the growth phase is so short that the hairs do not exit the scalp at all.

Finasteride stops the production of DHT. It works as an inhibitor of 5-alpha-reductase, the enzyme which converts testosterone into DHT. This means that less DHT is present in the scalp (around 60% less), preventing further hair loss and in some cases, promoting hair regrowth.

Finasteride is suitable for men with mild to moderate male-pattern hair loss but it is not effective for men with complete hair loss. Finasteride is not advised in men who are actively planning for a pregnancy with their partner. Finasteride is not suitable for women. A full list of warnings and precautions is contained within the Patient Information Leaflet (PIL) which you should always read before taking finasteride for the first time.

In a trial* of 1553 men with male-pattern hair loss, treatment with finasteride resulted in improved scalp coverage in around two-thirds of men and slowed the progression of hair loss in the other one-third. Only about 1% of men in the trial lost hair whilst taking finasteride.

* https://www.ncbi.nlm.nih.gov/pubmed/9777765

Occasionally, men taking finasteride experience changes in their sexual function. In trials*, only around 1.5% of men experienced symptoms such as erectile dysfunction, decreased libido and ejaculatory dysfunction. Stopping treatment usually leads to resolution of these symptoms.

Other rare side effects of finasteride include testicular pain, depression and breast tissue growth/tenderness. A complete list of side effects is available in the Patient Information Leaflet (PIL) enclosed with your medication, which you should always read before taking it for the first time.

* https://jamanetwork.com/journals/jamadermatology/article-abstract/422032

You should start noticing reduced hair loss and/or regrowth of hair after about four to six months. The best results appear after one to two years of treatment.

In most cases, any improvement in the quality or quantity of your hair that you noticed during the time you were taking finasteride will be lost within 6-12 months of stopping treatment.

If you forget to take your dose of finasteride one day, don’t worry. Just take your dose as normal - you should not double the dose to make up for the dose you forgot.

Not currently, no. For use in male-pattern hair loss, finasteride is only available on private prescription.