What causes splitting nails and how can I treat it?

Splitting Nails: Causes and Treatment

For splitting nails (onychoschizia), the most effective treatment is combined oral biotin 1 mg/day plus pyridoxine 100 mg/day for 3 months, which achieves complete resolution in approximately 70% of cases. 1

Understanding Nail Splitting

Nail splitting, medically termed onychoschizia, is characterized by lamellar splitting of the distal nail plate where the nail separates into horizontal layers. 1, 2 This condition affects up to 20% of the population, with fingernails more commonly affected than toenails, and women over 50 years particularly susceptible. 2

Primary Causes

Idiopathic brittle nail syndrome is the most common cause when no underlying condition is identified. 2 The condition manifests as:

• Longitudinal ridging with splitting or brittleness of the nail plate 3
• Nails that split, flake, crumble, become soft and lose elasticity 2
• Progressive dehydration of the nail plate from environmental factors 4

Secondary causes that must be excluded include:

• Inflammatory conditions: Psoriasis and lichen planus cause nail thinning and longitudinal ridging 3, 5
• Fungal infections: Present with thickening, discoloration, and friable texture, requiring confirmation through direct microscopy and fungal culture 3
• Chronic paronychia: Infection and inflammation in the nail matrix area from chronic moisture exposure 3
• Systemic conditions: Hypochromic anemia, peripheral vascular disease, and endocrinopathies 6
• Medication-induced: Particularly chemotherapy agents like taxanes 7
• Repetitive trauma: From occupational or habitual factors 5

Treatment Approach

First-Line Pharmacologic Treatment

The combination of oral biotin 1 mg/day plus pyridoxine 100 mg/day for 3 months is superior to either agent alone, achieving:

• Complete response (>90% improvement) in 69.6% of patients versus only 10-11% with single agents 1
• Partial response (>50% improvement) in an additional 30.4% of patients 1
• No adverse events reported 1

Biotin monotherapy at 1 mg/day can be considered if combination therapy is not feasible, though efficacy is significantly lower. 1, 2, 4

Topical Management

Daily application of topical emollients to cuticles and periungual tissues is essential for maintaining the nail barrier. 7, 3, 8 Protective nail lacquers can restructure the affected nail plate. 3

Biomineral formulations applied topically and/or as oral supplements have shown efficacy:

• Improved nail hardness by 40-50% after 3 months 9
• Reduced nail roughness by 12-18% across treatment arms 9
• Well-tolerated with no adverse events 9

Essential Preventive Measures

The American Academy of Dermatology and ESMO guidelines emphasize these protective strategies: 7, 8

• Avoid excessive moisture: Wear protective gloves over cotton liners when cleaning or working with water/chemicals 7, 8
• Proper nail trimming: Cut nails straight across, not too short, avoiding trauma to the nail matrix 7, 8
• Minimize trauma: Avoid nail biting, cutting cuticles, or applying excessive pressure 7
• Gentle nail care: Use mild cleansers and avoid harsh nail products or artificial nails 8
• Appropriate footwear: Wear comfortable, well-fitting shoes with cotton socks 7

When to Investigate Further

Obtain fungal studies (direct microscopy with KOH preparation and fungal culture) if nails show: 7, 3

• Thickening and discoloration with friable texture 3
• Soft nail surface that becomes crumbly 7
• Previous antifungal treatment failures 7

Consider inflammatory dermatoses when: 3, 5

• Multiple nails affected with uniform pattern 5
• Associated skin lesions present 5
• Nail thinning with longitudinal ridging 3, 5

For inflammatory causes affecting fewer than 3 nails, the American Academy of Dermatology recommends intralesional triamcinolone acetonide 5-10 mg/cc for nail matrix involvement. 3

Common Pitfalls

• Misdiagnosing fungal infection: Unlike onychoschizia, fungal infections typically cause thickening and discoloration, not just splitting. 7, 3
• Using formaldehyde-based hardeners: Modified nail varnishes or dimethyl urea are preferred over formaldehyde products. 6
• Inadequate treatment duration: Improvement requires 6-9 months due to slow nail growth rates. 1
• Ignoring occupational factors: Household chores and wet work are particularly damaging and must be addressed. 6

Expected Timeline

Nail lesions become evident only after several weeks of treatment due to the slow growth rate of the nail plate. 7 Assessment of treatment response should occur at 6-9 months, not earlier. 1