What Happens When Multiple Hairs Grow in One Follicle?

If you’ve ever looked closely at a hair that seems darker or thicker than usual, you may have noticed that it’s not actually a single hair at all. It’s several hairs sprouting from the same follicle.
This condition, known as pili multigemini, is not usually dangerous or damaging to your hair or skin.
What is pili multigemini?
Pili multigemini is when several hairs emerge from a single hair follicle. It’s most commonly seen in penis owners’ beards and on the scalps of children, but it can happen anywhere on your body where hair grows.
Researchers don’t know exactly what causes the difference in growth, but it’s thought to be genetic. Pili multigemini tends to run in families.
Because the condition doesn’t usually cause any concerns, researchers think it may be more common than many people realize: We simply don’t notice these overachieving follicles.
A quick primer on hair growth
Hair grows in four distinct phases. The first period, known as the anagen phase, can take 2 to 6 years.
During the anagen phase, the base of your hair follicle plumps up like an onion and begins building a hair. That’s the stage when pili multigemini happens.
Down in the bulb of your follicle, your hair splits into several shafts. Each one is wrapped in its cuticle. Your separate hairs then continue to grow from the same follicle.
During the catagen phase, your follicle shrinks. Your hair breaks away from your follicle base, but remains “rooted” in place. This transitional phase usually lasts from 10 days to several weeks.
The telogen phase marks the end of hair growth. Your hairs remain in place, but new hair growth begins in the same follicle. Telogen generally lasts close to 3 months.
Finally, in the exogen phase (which some researchers sayTrusted Source is really the end of the telogen phase), your hair falls out. How long it takes for a hair to be shed depends on where it’s located.
Your eyelashes, for example, may fall out in a couple of weeks. Your hair on your head could take as long as a year to fall out. It’s considered complete