Hair structure and direction of growth play a role in ingrown hairs. A curved hair follicle, which produces tightly curled hair, is believed to encourage the hair to re-enter the skin once the hair is cut and starts to grow back. Shaving creates sharp edges in this type of hair, especially if the hair is dry when shaved.
You might also get an ingrown hair if you:
- Pull your skin taut during shaving — which allows the cut hair to draw back into the skin and re-enter the skin without first growing out
- Tweeze — which also can leave a hair fragment under the skin surface
When a hair penetrates your skin, your skin reacts as it would to a foreign body — it becomes inflamed.
March 13, 2015
- Dorland's Illustrated Medical Dictionary. 32nd ed. Philadelphia, Pa.: W.B. Saunders; 2011. http://www.dorlands.com/index.jsp. Accessed Jan. 27, 2015.
- Pseudofolliculitis barbae. The Merck Manual Professional Edition. http://www.merck.com/mmpe/print/sec10/ch124/ch124d.html. Accessed Dec. 5, 2014.
- Goldstein BG, et al. Pseudofolliculitis barbae. http://www.uptodate.com/home. Accessed Jan. 27, 2015.
- Alexis A, et al. Folliculitis keloidalis nuchae and pseudofolliculitis barbae: Are prevention and effective treatment within reach? Dermatologic Clinics. 2014;32:183.