Risk factors for pilonidal disease formation:

1. Infection in the sebaceous glands of the skin (folliculitis). This infection is common in adolescents (pimple, zit) and is also common in those who are prone to skin infections in the back, armpits or groin folds (in diseases like suppurative hidradenitis and severe acne).
2. A genetic/hereditary tendency: some of those suffering from pilonidal disease have close family members with a similar disease.
3. Hormonal/endocrine changes as those occurring during adolescence.
4. Overweight: Obese may have a deep, humid, less ventilated natal cleft, creating an ideal environment for bacterial proliferation and causing skin maceration and infection.
5. Smoking increases the propensity for skin infections (perhaps by compromising the immune mechanism against skin infections).
6. Prolonged local injury: During World War II, pilonidal disease was nicknamed "Jeep riders disease" and was attributed to the damage caused by prolonged jerky rides in jeeps.  In a study examining youngsters during military service, pilonidal disease was found to be more common in those engaging in driving professions.
7. Inadequate personal hygiene may contribute to pilonidal formation.
8. Tight clothes may promote local infection by pushing the buttocks toward one another and preventing ventilation of the cleft.
9. Previous pilonidal surgery: Recurrence rate of pilonidal disease after surgery may reach 20-40%.
10. Hairiness, particularly dark/black, may contribute to pilonidal formation.
11.  A combination of the factors above and mutual influence among them.