Some daily hair loss is natural, and helps make way for new hair. This is the natural process of hair regeneration and can take up to 10 years. However, losing more than 150 hairs a day is considered abnormal hair loss. Many people suffer from excessive hair loss, but do not know what is causing it. Knowing the cause is important in order to treat the condition effectively.

The most common cause of hair loss in men and women is a hormonal imbalance known as androgenic alopecia. This type of hair loss is caused by a hormone called Dihydrotestosterone, or DHT. Those who have a lot of receptors in their hair follicles for DHT are the ones who suffer this type of hair loss. Androgenic alopecia is inherited from the mother and/or the father. The condition causes hair loss by continuously shortening the growth phase of the hair regeneration cycle. In addition, the hair follicles begin to produce progressively thinner hairs until the follicles completely die.

In men, androgenic alopecia causes the familiar male-pattern baldness typically beginning at the temples and/or crown of the head and then spreading. By contrast, in women, androgenic alopecia causes hair thinning throughout the scalp, and the hair line does not recede so there are no actual bald spots. Androgenic alopecia is an inherited condition. The current treatment for it uses drugs that act as DHT blockers or inhibitors. Eventually, gene therapy will be used to protect the follicles from DHT once this method is perfected and widely available.

Some hair loss issues are specific to women. Often women lose hair shortly after pregnancy. This is because much of the hair enters a dormant phase at the same time due to postpartum hormonal changes. The hair loss becomes most noticeable about 3 months after giving birth. This condition may last up to 6 months, but for the vast majority of women, normal hair growth resumes.

Another cause of hair loss in women is the birth control pill, specifically the type with a high androgen index. For women who are at higher risk for androgenic alopecia due to genetic factors, the birth control pill can induce the onset of the condition at a much earlier age than it would normally occur. For women, androgenic alopecia usually starts in the 30s, but some women who take the pill get it in their 20s. Sometimes the hair loss occurs after use of the birth control pill has stopped. Often, the hair will grow back after several months of staying off the pill, but sometimes the hair loss is permanent. To prevent this from occurring, it is recommended that for those women whose relatives suffer from female pattern hair loss, a birth control pill with a low androgen index be used.

Sometimes illnesses and infections can cause hair loss. Those who get extremely ill with a flu, fever or infection may experience hair loss several weeks after the fact. This is usually a very short-term phenomenon and the hair grows back quickly. The fungal infection of the scalp known as ringworm is a contagious disease most often found in children. It can cause hair loss, but once treated with medication, the hair should fully recover.

The thyroid gland, located in the front of the neck, can also cause hair loss. When hyperthyroidism or hypothyroidism occur, more testosterone gets converted into DHT, which causes hair loss. When the thyroid gland is not functioning properly, it is believed to reduce the metabolism of the hair follicles, resulting in their premature release from the shaft. For some people, the thyroid drug levthyroxine can also cause hair loss. However, a proper thyroid medication is needed to address thyroid malfunction. For some, multiple vitamins and evening primrose oil has proven to be an effective treatment for thryoid-related hair loss.

Thyroid drugs aren't the only medications and medical treatments that can cause hair loss or thinning. Drugs such as blood thinners and those used to treat depression, gout, arthritis, and cardiovascular conditions can also cause hair loss. Chemotherapy and radiation used to fight cancer often cause the patient to lose almost all of his or her hair, because the hair cells stop dividing. The hair does grow back after the treatment ends although it can take several months. Major surgery can also induce hair loss due to shock. This hair usually grows back in a few months, but the hair loss may continue for those with ongoing ailments that continually stress the system. Stress related hair loss is usually a temporary phenomenon, and the hair usually regenerates once the stress has subsided. However, for those predisposed to androgenic alopecia, stress may trigger or exacerbate the condition and resulting hair loss.

Diet and improper nutrition can also induce hair loss. A low protein diet often results in hair loss. When the body doesn't get enough protein, much of the hair that would normally be in the growing phase moves into the resting phase in order to conserve it. Several months later, this can result in severe hair loss, with the hair easily falling out of its roots. Once the person starts eating adequate amounts of protein, normal hair growth should resume fairly quickly. Too much or too little of certain vitamins can also cause hair loss. For example, an iron deficiency, or an excess of vitamin A have been known to cause hair loss in some people. Some women who have heavy periods develop an iron deficiency. This can be corrected with iron supplements.

Another cause of hair loss is alopecia areata. It results in the loss of coin-sized patches of hair, and is thought to be the result of the immune system attacking the hair follicles. About half of sufferers get their hair back within a year without any treatment. Others respond to topical medications, light therapy and drugs.  However, in about 10% of cases, only some or none of the hair will grow back. 

Sometimes hair loss can be caused by physical trauma, such as pulling. If the hair is pulled repeatedly or for long times, the stress can result in permanent hair loss. Other trauma to the hair can result from chemical treatments such as bleach, dyes, etc. If these chemicals are used in an unsafe way, it can result in hair loss. Braids or weaves, often worn by black people, can cause stress on the hair follicle resulting in hair loss if they are too tight.

Hair loss has a multitude of causes and can be devastating to those who suffer from it. If you are unsure of what the cause of your hair loss is, it's best to consult a dermatologist. The sooner you address hair loss, the better the chances you have of halting and reversing it.

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