DHT (dihydrotestosterone) is a male hormone that's responsible for the development of many of the physical characteristics associated with adult males. It's converted by the body from the primary male sex hormone testosterone. During puberty DHT becomes active, causing the growth of facial hair, for example.
Some men, especially those with a history of hair loss in the family, are born with a genetic sensitivity to DHT. It's one of the key causes of male pattern baldness.
Why does DHT cause hair loss?
DHT binds to cells in your hair follicles, causing the follicles to shrink and weaken. As a result, hair is produced more slowly than normal.
The action of DHT either shortens the growing stage of the hair (called the 'anagen' phase) or lengthens its resting stage (the 'telogen' phase).
The hair shaft becomes finer with each new growth cycle until, eventually, the hair stops growing altogether. This is why you see hair thinning over a period of time.
How do DHT blockers work?
As DHT sensitivity is believed to be the main cause of hair loss in men, the most effective way to slow down and stop a receding hairline and male pattern baldness is to block DHT.
This can be done using a treatment designed to prevent testosterone from converting into DHT. DHT blockers can slow down or stop hair loss, while promoting growth.
DHT blocker medicines
Finasteride is the generic version of Propecia, a prescription medicine that is a DHT blocker. This medicine works by targeting the enzyme responsible for converting testosterone into DHT. By inhibiting the action of this enzyme, production of DHT is reduced.
Finasteride can be taken by men, aged 18 or over, experiencing male pattern hair loss. It is taken in tablet form and the recommended dose is one tablet each day. It can help increase hair growth and prevent further hair loss but it needs to be taken continuously to maintain hair growth. Stopping the treatment will result in any new hair falling out within nine to 12 months.
Are there any side effects to finasteride or Propecia?
As with all medicines, taking finasteride can have potential side effects, but this doesn't mean that everyone will get them. However, there are side effects for a small number of men. These include:
• Impotence or difficulty gaining and keeping an erection
• Low libido or sex drive
• A decrease in the amount of semen produced during sex
• Ejaculation problems
If you experience more severe side effects such as changes in breast tissue (such as lumps, pain, enlargement or nipple discharge), depression, anxiety and panic attacks or an allergic reaction to the medicine, you should stop taking it immediately and visit your Doctor.
The patient information leaflet contains a full list of side effects. Make sure you read it before you take the medicine.
Is it suitable for everyone?
• Finasteride shouldn't be taken by women, teenagers or children. Pregnant women or those trying to become pregnant shouldn't come into contact with the tablets, especially if crushed or broken, as this could affect the development of the sexual organs of a male baby
• Finasteride should not be taken by men with partners who are pregnant or trying to get pregnant
• Finasteride is not suitable for men already taking finasteride or another medicine called dutasteride for prostate problems
• Finasteride is not suitable if you are allergic to finasteride or any other ingredient in the tablets
Your clinician or doctor will always check before prescribing you finasteride that it's suitable for you. If you're concerned about any symptoms you experience while taking finasteride, see your GP as soon as possible.
What other treatments are there?
Minoxidil isn't a DHT blocker but can help with a receding hairline caused by pattern hair loss. It can prevent further hair loss and help hair regrowth.
Minoxidil is available from your pharmacist and comes as a liquid or foam. It's available in various concentrations. Make sure you read the patient information leaflet for the appropriate dosage of the product and instructions on how to use it.
The product is applied to the scalp to relax the muscle walls of the blood vessels. It promotes growth by increasing blood flow to the hair follicles. This leads to hairs moving from the resting to the growth phase of the cycle, and extends the growth phase.
It's important to remember, however, that this form of treatment has to be maintained. Once you stop using it, the effect on hair growth stops and you will revert to your previous pattern of hair loss.
Are there any side effects to minoxidil?
Possible side effects of using minoxidil include:
• Initial hair loss as older hairs are shed and replaced by newer, actively growing hairs
• Itchy eyes
• Irritation and dryness of the skin
Read the patient information leaflet for a full list of side effects.
No information is available on the combination of finasteride with minoxidil in the treatment of male pattern hair loss. Speak to your doctor or pharmacist for advice.