What Causes Lip Hair Growth?

The growth of hair on the upper lip can be embarrassing for women. They may tweeze, wax, laser, bleach or shave the hairs to correct the problem. The term for excessive hair growth in women is "hirsutism." Some women have very light or no hair growth above the lip, while others can grow a bush as thick as a man's mustache. There are several factors that can contribute to the growth of hair on a woman's upper lip.

Hair Growth Cycle

• Hair grows in a cycle. It starts in a pouch below the skin's surface called a follicle. Blood, nutrients and other substances flow to the hair follicle and determine the speed and thickness at which a hair will grow. Once the hair pushes up through the skin, it continues to grow to a certain length and then goes into a regressive phase. After a while, the hair will fall out on its own and then a new hair starts to form beneath the surface.

Testosterone

• The main cause for excessive hair growth is the amount of male hormones in the system. The high level of testosterone that occurs naturally in men is the reason why many men have very active facial hair growth. Testosterone levels in the blood cause follicles to grow hair fast and thick. The sebaceous glands, which are located in the skin, also directly affect hair growth and are sensitive to the presence of male hormones. Unfortunately, some women have testosterone as well---some more than others. This is what causes unwanted lip hair growth in females. Testosterone levels and excessive hair growth in both women and men are hereditary.

Puberty

• When girls and boys hit puberty, hormones flare and hair growth above the lip starts. Children have fine hairs (also called vellus hairs). But as children reach puberty, the hair becomes coarser and thicker, depending on the amount of male hormones produced.

Pregnancy Hormones

• When a woman becomes pregnant, her hormone levels can go out of control and cause excessive hair growth. While this mostly happens in hair on the top of the head, it also frequently occurs on the face and above the lip. Luckily, because pregnancy is temporary, so is lip hair growth in most cases.

Medications

• Excessive lip hair growth in a woman can also be caused by certain medications (and even some birth control pills) that contain synthetic hormones, steroids and other substances. See the References section for a list of medications.