Hair grows in cycles so that at any one time around 85 to 90 percent of the hair on our head is in the growth phase, known as Anagen, and the other 10 to 15 percent is in the resting phase or Telogen. There are many reasons why hair might stop growing sooner than it should or start to fall out in greater amounts than normal but the two most common types of hair loss or hair thinning that can occur in both men and women are known as Telogen effluvium and Androgenetic alopecia.

Telogen Effluvium is where a large number of hairs are shed during the Telogen phase of the hair growth cycle leading to widespread thinning of the hair. This can happen at any time in someone's life and can be triggered by physical or emotional stress or medication or hormonal influences.

Androgenetic alopecia is related to hormone levels in the body and can be hereditary. It is the main cause of baldness in men and although it can affect women too, the pattern of baldness is different. In women it tends to manifest itself as widespread thinning of the hair whereas in men it appears as the typical male baldness pattern. This type of hair loss is linked to levels of the chemical dihydrotestosterone or DHT.

What is DHT?

DHT or Dihydrotestosterone is one of the male hormones formed when testosterone interacts with the enzyme 5 alpha reductase. High levels of DHT appear to be responsible for male pattern hair loss, thinning of the hair, shortening of the growth phase of the hair and miniaturisation of the hair follicle so that eventually, no visible hairs are produced.

Faster hair growth products work in a number of different ways to promote hair growth but the majority of them concentrate on reducing levels of DHT and/or stimulating the activity of the hair follicles to produce new growth.

The following list represents some of the most common hair growth products available.

Minoxidil (Rogaine, Regaine, Headway)

This product was originally used to treat high blood pressure but one of the side effects of the treatment was found to be increased hair growth. Minoxidil is sold under the brand names of Rogaine in the US and Regaine and Headway in the UK and is available without prescription. It is a topical application that you apply directly to the scalp on a daily basis.

Although it is not clearly understood exactly how it works, its hair growth properties are thought to be due to a combination of factors including increasing the supply of blood to the scalp, stimulating the hair follicles into activity, and prolonging the growth phase of the hair growth cycle. It is used to treat male pattern baldness and tends to be effective on the top of the head and not on the temples or the typical receding hairline. It can also be used by women but at a lower dose than for men.

Finasteride (Propecia)

Finasteride is better known under the brand name Propecia. It works by inhibiting type 2 5-alpha reductase which converts testosterone into dihydrotestosterone (DHT). Proscar is also a brand name for the active ingredient Finasteride and is used to treat enlarged prostate rather than hair loss. Neither Propecia nor Proscar are suitable for women.

Dutasteride (Avodart, Avolve)

Dutasteride is taken internally and is only available on prescription. It is sold under the brand names Avodart and Avolve and is currently prescribed for Benign Prostatic Hyperplasia (BPH) and not specifically for hair loss. It also works by decreasing levels of DHT in the body; however, instead of inhibiting only one type of 5-alpha-reductase enzyme like Finasteride, Dutasteride inhibits two different types so is extremely effective at lowering DHT levels.

Important to note

As with any product whether taken internally or applied externally, there can be side effects, for example, side effects associated with some of the hair loss products above include loss of libido, rashes, headaches and impotence.

Before taking any product to promote faster hair growth, it is important to check with your doctor to make sure there are no contraindications specific to you and to make sure that any product is suitable for your particular condition.

Another point worth bearing in mind is that results don't happen overnight, it can take several months before there is any noticeable difference in hair growth.