Which of the following conditions do NOT require medical referral?

Onychophagy, commonly known as nail biting, is a condition that often does not require medical intervention. While it can lead to cosmetic issues or damage to the surrounding skin and nails, it is primarily a behavioral issue rather than a medical one. Many individuals may manage it through behavioral modification techniques or self-care strategies without needing a referral to a healthcare provider.

In contrast, conditions like hyponychium, eponychium, and onycholysis generally involve more significant medical concerns. Hyponychium refers to the area underneath the distal edge of the nail, and issues in this area could indicate underlying infections or trauma. Eponychium, the cuticle area, when inflamed or infected, may require medical attention to prevent further complications. Onycholysis, the separation of the nail plate from the nail bed, can be a sign of various medical conditions or infections, which definitely necessitate evaluation by a healthcare professional. Therefore, onychophagy stands out as a condition that typically allows for self-care and does not require a referral to a medical professional.