Hair loss in the beard, especially in round bald patches, may be caused by a condition called alopecia areata barbae. This condition is considered an autoimmune disease because the immune system mistakenly attacks as foreign tissue the cup-shaped hair follicles from which hairs grow. Why this occurs is largely unknown, but the condition is generally thought to be passed or triggered genetically. Other causes may include hormonal imbalance, ringworm, a hidden tooth infection or stress.
According to the U.S. National Library of Medicine and the National Institutes of Health, the cause of bald patches on the beard, or alopecia areata barbae, is unknown. Because one-fifth of those with this condition have a family history of alopecia, it is thought that genetics may be a trigger.
This is not true if bald patches appear at an early age in the beard. First beards do tend to come in patchy in many adolescents. Hair follicles mature at different rates. Also, hormones control beard growth, and hormonal changes may disrupt the even growth of a beard. A man's hormones do not settle down until he is about 30 years of age. Many patchy beards become regular by that age.
Although it isn't common, ringworm of the beard can occur. This infection is not caused by a worm but by a fungus that lives on the top layer of the skin. Ringworm is contagious, and the carriers, who themselves do not have ringworm, can be human beings or dogs or cats.
A beard that is infected by ringworm has bald patches. Usually the bald patches spread outwards while the centre of the patch heals. Sometimes, but not always, a ring pattern is formed. If the infection is severe, the bald skin appears red, crusty, swollen with blisters and is painful.
Ringworm of the beard is easy to treat with prescribed medication such as griseofulvin.
Hidden Tooth Infection
As reported by the Science Daily in 2007, research at the University of Granada's Department of Stomatology established for the first time a relationship between alopecia areata and dental disease.
Professors Montoya and Soriano in Granada found that bald patches in the skin can be caused by a hidden tooth infection. They also found that these bald patches are not always in the same area on the face as the infection. In fact, they can be quite far from the infection site.
It is thought that the problem is an immune system reaction. When there is a tooth infection, the immune system wrongly attacks the beard hair follicles.
Since severe physical or emotional stress can cause baldness of the scalp and can actually cause one-half to three-quarters of a man's hair to fall out, emotional stress is thought to be an unproven factor in the development of a patchy beard.
After considerable or sudden stress, a man's hair can come out in handfuls, a condition known as telogen effluvium. Stress and hair fallout are generally not associated because hair can fall out weeks or even months after the stress subsides.
Although unproven, stress may sometimes be a factor in patchy beards.