A partial or complete loss of hair is called alopecia. It can develop gradually or appear as patches.
Both men and women tend to lose the thickness and amount of their hair as they age. This type of baldness is generally not caused by disease and is either related to aging, is hereditary or is due to changes in the testosterone hormone. Hereditary baldness affects men much more and can occur at any time in life after puberty.
Physical or emotional stress may cause a person to lose one half to three quarters of their scalp hair. This hair tends to fall out in handfuls while shampooing, brushing your hair or running your hands through it. If the cause of hair loss is being sick (such as a fever), radiation therapy, the use of medication or another reason, treatment is not necessary. Hair will grow back again once the condition is gone or once a person has completed their recovery process.
The MedlinePlus webpage recommends seeing a specialist if your hair loss follows an atypical pattern, if you are losing it quickly or at an early age; if you experience pain or itching; if the skin on your scalp becomes red or scaly; if you have acne, facial hair, or an abnormal menstrual cycle; or the if you notice any weight gain, muscle weakness, intolerance to low temperatures or fatigue. If these symptoms arise, a medical history and a careful physical exam are enough to diagnose the cause of your hair loss.
Every day, people lose approximately 100 hairs. The scalp contains about 100,000 hairs.
Related article: The basics of hair care