Woman with arm raised

Women typically shave their underarm hair to make themselves appear more attractive, and the idea of thinning hair under the arms can seem like a positive development. Unfortunately, there can be many medical reasons why hair can thin or fall out on the body, many of which need to be treated by a doctor.

Thyroid Dysfunction

When the thyroid gland is not functioning correctly, it can cause all of the other systems in the body to have problems as well. One of these problems is a constricting of the hair follicles, which can suffocate the hair roots and lead to hair loss. This hair loss can be witnessed all over the body, including under the arms. Taking a thyroid replacement hormone will help reduce this hair loss.


Diabetes is a disease that causes the pancreas to become dysfunctional and discontinue producing insulin. If insulin is not available in the body, blood sugar levels will become unbalanced. This can result in improper function of other systems in the body, such as the circulatory system, which helps produce hair growth. Hair growth can become inhibited all over the body but will usually improve once blood sugar levels return to normal.


Alopecia is a skin condition that is effected by nerves and stress, and it can cause hair to fall out on the scalp and body. Hair loss due to alopecia usually appears in patches rather than thinning and can be improved by reducing stress levels.


Psoriasis is an autoimmune condition that causes the skin to produce pink patches of skin covered in silvery scales. These scales can be extremely itchy and can suffocate the hair, leading to hair loss. Since psoriasis effects skin around the scalp, arms, under arms, legs and neck, hair loss often is seen in these locations. Use of topical psoriasis creams and lotions can help cause it to go into remission, which can improve hair growth.


Malnutrition can cause the body to become depleted of vital nutrients needed for hair growth and development. If the body does not have the necessary nutrients needed to produce healthy hair growth, this can result in hair loss all over the body. Taking a multivitamin daily can improve hair growth and hair strength.