Pilonidal sinus, medically known as pilonidal sinus and commonly referred to as ingrown hair disease, arises when body hairs shed and accumulate in the sacrococcygeal region, leading to an infection and the formation of a fluid-filled cyst. Significant factors contributing to its development also include increased hair production in men due to hormonal changes, often starting from their 20s, and conditions like obesity.

Key factors that generally increase the risk of pilonidal sinus are:
* Being male
* Sedentary lifestyle
* Obesity
* Having thick and coarse body hair
* Occupations requiring prolonged sitting
* Previous history of pilonidal sinus