Causes of Ingrown Toenail
Ingrown toenails are primarily caused by improper nail trimming technique, tight-fitting footwear, and repetitive trauma, with genetic factors and hyperhidrosis also playing significant roles. 1, 2
Primary Causes
Improper Nail Care
- Incorrect nail trimming technique: Cutting nails too short or rounding the corners instead of cutting straight across 2, 3
- Poor foot hygiene: Failure to keep feet clean and dry 4
Footwear Issues
- Tight or ill-fitting shoes: Causes compression of the toes and increased pressure on nail edges 2, 3
- Occlusive footwear: Creates warm, moist environment conducive to nail problems 4
Physical Factors
- Trauma: Both repetitive minor trauma (e.g., from sports) and acute injuries 1, 2
- Nail plate abnormalities: Thickened nails or pincer-shaped toenails 3
- Hyperhidrosis: Excessive sweating softens the nail fold, making it more susceptible to nail penetration 1, 5
Contributing Risk Factors
Anatomical Factors
- Toe deformities: Hallux valgus or other toe deformities causing pressure from abutting digits 3
- Subungual exostosis: Bony growth under the nail 3
Demographic Factors
- Age: Biphasic presentation with peaks in the second and fifth decades of life 5
- Gender: Slightly higher prevalence in males, particularly in the 14-25 age group 3
Medical Conditions
- Genetic predisposition: Family history of ingrown toenails 4, 2
- Diabetes: Increases risk of complications from ingrown toenails 4
- Fungal nail infections (onychomycosis): Can distort nail growth 4
- End-stage renal disease: Associated with higher risk of foot complications 4
Special Populations at Risk
Athletes
- Higher prevalence due to:
- Increased sweating
- Repeated nail trauma
- Sports with sudden starting/stopping (tennis, squash, football)
- Sports requiring tight footwear 4
Diabetic Patients
- Almost three times more likely to develop nail problems 4
- Higher risk of complications due to:
- Peripheral neuropathy (reduced sensation)
- Poor circulation
- Impaired wound healing 4
Prevention Strategies
- Trim nails straight across, not too short, avoiding rounding corners 6
- Wear properly fitting shoes with adequate toe box space 6
- Apply daily emollients to cuticles and periungual tissues 6
- Keep feet clean and dry to prevent maceration of tissues 4
- For those with hyperhidrosis, use moisture-absorbing socks and antiperspirant foot products 5
- Regular foot checks for those at high risk (diabetics, peripheral vascular disease) 4
Understanding these causes can help guide preventive measures and appropriate treatment strategies to reduce the risk of ingrown toenails and their complications, particularly in high-risk populations.