Hair loss, known as baldness (or baldness), is referred to in medicine as androgenic alopecia. Alopecia means hair loss, and androgenic refers to the influence of male hormones in the process.

Many people think that baldness is a problem exclusive to men, but in fact, the definitive loss of hair affects women in the same proportion. The difference is that, as in women the baldness is usually less intense and, therefore, more discreet, it is more easily camouflaged.

Hair life cycle

The hair and hair are cylindrical structures composed of proteins, mainly keratin, which grow through the skin through the hair follicles located in the deepest regions of the dermis. The whole body, except the palms and soles, have hair follicles and hair. In some places, because they are very light and fine, the hair may go unnoticed, but they are there.

Hairs show different characteristics and speed of growth in each location of the body, which is easily noticeable when comparing eyelashes, hair, pubic hair and beard, for example. The scalp has, on average, 100,000 hairs, with an average growth of 1 to 2 cm per month.

Every day we lose approximately 75 to 100 threads. Depending on the time of year, the stage of life and environmental factors, this loss may be even greater. The life cycle of hair is divided into 3 phases:

1- Anagen or hair growth phase. It lasts on average from 2 to 3 years, and can reach up to 7 years.
2- Catagen or involution phase. It only lasts a few weeks, on average two or three. At this stage the hair stops growing and the follicle begins to regress.
3- Telogen or detachment phase. Lasts 3 to 4 months. The hair loosens from the papilla and a new phase of growth begins.

Hair cycle

As the new hair grows, the old “dead” one is pushed out of the hair follicle and falls out. This process of growth and death occurs throughout the body at different speeds for each type of hair. Hair that takes a long time to grow ends up falling off before they get big. This cycle explains why some hairs never exceed certain sizes and why the hair on the head rarely exceeds the waist line, even if it is never cut.

Of the 100,000 hairs on your scalp at the moment, approximately 85% are in the growth phase, 5% in the involution phase and 10% in the fall phase.

What causes baldness?

Androgenic baldness or alopecia is caused by a shortening of the growth phase (anagen), by a progressive thinning of the hair and by the reduction of the size of the follicles, causing the root to be closer to the surface of the skin.

This follicle miniaturization is a hereditary process and mediated by male hormones. To be more exact, the problem occurs in those patients who overproduce an enzyme called 5 alpha-reductase, which turns the male hormone testosterone into its dihydrotestosterone derivative. Genetic factors determine this excessive production.

Dihydrotestosterone binds to receptors found in some hair follicles causing their size to decrease. Therefore, baldness occurs in those individuals with high levels of dihydrotestosterone and numerous follicles with receptors for this hormone. The different distributions of dihydrotestosterone receptors among individuals explains why we have different types of baldness.

The figure below illustrates the most common male hair loss patterns.

Male pattern baldness

In women, androgenic alopecia is more diffuse through the scalp, however, it is less intense. In general what occurs is an intense thinning of the hair strands, which occurs mainly in the center and at the apex of the head. Complete baldness, as in men, is rare in women.


The treatment of male pattern baldness is based on the use of two drugs:

  • Minoxidil in topical solution (approved for men and women).
  • Finasteride orally (approved for men only).


The minoxidil solution for direct application to the scalp improves hair loss by increasing the time of the anagen phase and stimulating the growth of miniaturized follicles. The results take at least 4 months, being more pronounced at the apex of the scalp and smaller in the frontal region. Treatment is for life. With the interruption, hair loss returns.


Finasteride is a drug originally used in prostatic hypertrophy, but over time it has been noticed that it has a side effect of reducing hair loss in patients.

Finasteride is a blocker of the enzyme 5 alpha-reductase, which, as explained earlier, prevents the transformation of testosterone into dihydrotestosterone (DHT), responsible for the negative effects on hair follicles.

In general, the use of 1 mg tablets per day for at least 1 year is recommended. With the use of Finasteride there is an increase in the number of hair strands, which also become thicker and stronger. If the drug is stopped, however, within 6 to 9 months the patient loses all the new hair that had grown.

Finasteride in women has yet to be effective and has been shown to cause fetal malformations. Therefore, it is not a drug indicated for female pattern baldness.

There is no evidence that laser-based treatments or other types of lights, widely publicized in the media, are really effective in preventing hair loss. Resist the temptation to try miraculous hair tonics. In addition to not working, they can accelerate the hair loss process.

If you have hair loss, see a dermatologist so that he can decide the best therapeutic strategy for you. Don’t self-medicate. Remember that both finasteride and minoxidil have side effects and contraindications. In addition, there are several other causes of hair loss besides androgenic alopecia, which should not be treated with either of these two drugs.

Hair transplant

Permanent improvement of androgenic alopecia can be achieved through hair transplantation with follicular units, which is currently the basis of surgical treatment of baldness. The ideal candidates for hair transplantation are patients with stable and medication-controlled androgenetic alopecia, who want permanent improvements and have a suitable hair reservoir for transplantation.

In this form of treatment, the surgeon removes hair follicles from the occipital scalp (the back of the scalp where there is still hair) and transplants them to areas affected by baldness. The transplanted hair will maintain the characteristics of the donor site of the occipital scalp, which is relatively resistant to androgenic alopecia. Transplanted hair, therefore, tends to continue to be large caliber hair.

The major disadvantage of hair transplants is that they are expensive and painful.

Other types of hair loss

There are several other causes for hair loss. Unlike baldness, they usually cause localized and irregular losses. However, in diffuse cases they may resemble androgenic alopecia. Let’s name the most common causes:

The. Anagen effluvium: it is the hair loss that occurs, for example, in chemotherapy, radiotherapy or poisonings with mercury.

B. Telogen effluvium: occurs as a side effect of several drugs, vitamin deficiencies, psychological stress or  thyroid diseases or pregnancy (read: Telogen gravid effluent ).

ç. Traumatic alopecia: occurs due to mechanical and / or chemical trauma to the hair. It can arise after some hair straightening techniques with repeated traction associated with the use of chemicals. Some people with nervous breakdowns can pull their own hair out and have this type of alopecia.

d. Alopecia areata: it is an autoimmune disease in which the body starts to mistakenly produce antibodies against its hair follicles. The scalp is the most affected, but there may be hair loss anywhere on the body.