Causes of Hair Loss:

Anyone can experience hair loss, including men, women and children. Baldness typically refers to excessive hair loss from your scalp and can be the result of heredity, certain medications or an underlying medical condition. A number of causes for hair loss can be identified.

These include:

Age - Hairs break more easily, and hair follicles do not grow as much hair.

Birth control pills - More likely for women with inherited tendency of hair thinning.

Blow-drying - extreme heat can damage hair proteins, making them fragile and liable to break off.

Brushing - Brushing the hair during blow-drying can causes more damage to hair proteins.

Cancer treatment drugs - Chemotherapy drugs can cause hair cells to stop dividing 1-3 weeks after beginning treatment. Hair shafts become thin and break off as they exit the scalp. Total hair loss usually recovers after treatment ends.

Childbirth - 2-3 months after a woman delivers her baby, many hairs enter the resting stage of the hair cycle at once and may all fall out together.

Genetic predisposition - Some people are more likely to have higher levels of a hormone called dihydrotestosterone (DHT) which can cause pattern baldness, common baldness or androgenic alopecia.

Inadequate protein in diet - Protein malnutrition can trigger the body to respond by sending signals that hairs enter the resting phase. Massive hair shedding can occur two to three months later. Hair can then be pulled out by the roots.

Infections - Fungal infections such as Ringworm, or tinea capitus, may cause loss of patches of hair that are replaced with pink scaly skin.

Low serum iron - Iron deficiency sometimes produces hair loss

Thyroid disease - Both an overactive and underactive thyroid can cause hair loss.

Hormonal factors
If your thyroid gland isn't working right, it can also cause hair loss. (The thyroid gland sits in the front of the lower neck and makes important hormones that keep the body healthy.) Severe problems with nutrition also can result in unhealthy hair that falls out or breaks easily.

Medical conditions
A variety of medical conditions can cause hair loss, including:

• Thyroid problems: The thyroid gland helps regulate hormone levels in your body. If the gland isn't working properly, hair loss may result.
• Alopecia areata: In this condition, round patches of hair completely fall out. No one knows exactly what causes alopecia areata, but it looks like the body's own immune system attacks the hair follicles. It also runs in some families. In 95 out of 100 cases of alopecia areata, the hair grows back completely.
• Scalp infections: Infections, such as ringworm, can invade the hair and skin of your scalp, leading to hair loss. Once infections are treated, hair generally grows back.
• Ringworm: Kids who have a fungus called ringworm on their scalp might lose their hair. This infection causes the hairs to break close to the scalp.
• Trichotillomania: This is the fancy name for the habit of pulling and twisting your own hair. Some kids may pull their hair because they're stressed out or anxious about something. Hair will grow back when it's not being pulled, but some kids find it hard to stop. For these kids, the doctor can recommend treatment.
• Other skin disorders: Diseases that can cause scarring, such as lichen planus and some types of lupus, can result in permanent hair loss where the scars occur.

Other causes of hair loss
Hair loss can also result from:

Symptoms of hair loss
Hair loss can appear in many different ways, depending on the problem that's causing it. It can come on suddenly or gradually and affect just your scalp or your whole body. Some types of hair loss are temporary, while others are permanent.
Signs and symptoms of hair loss may include:

• Gradual thinning on top of head. This is the most common type of hair loss, affecting both men and women. In men, hair often begins to recede from the forehead in a line that resembles the letter M. Women typically retain a line of hair at the forehead but experience a broadening of the part in their hair.
  
• Circular or patchy bald spots. Some people experience smooth bald spots, often about an inch (2.6 centimeters) across. This type of hair loss usually affects just the scalp, but it sometimes also occurs in beards or eyebrows. In some cases, your skin may become itchy or painful before the hair falls out.
  
• Sudden loosening of hair. A physical or emotional shock can cause hair to loosen. Handfuls of hair may come out when combing or washing your hair or even after gentle tugging. This type of hair loss usually causes overall hair thinning and not bald patches.
  
• Full-body hair loss. Some conditions and medical treatments, such as chemotherapy for cancer, can result in the loss of hair all over your body. The hair usually grows back after treatment ends.