Daily contact with chemicals and the elements can make nails brittle and split. Fungal infections and hypothyroidism—low thyroid hormone—are other culprits. If you also notice weight gain, low mood, or fatigue, suspect your thyroid. Splits may point to low biotin, protein, or iron as well. Frequent washing, harsh cleansers, and cold, dry air weaken nails. Wear gloves, moisturize, and eat a balanced diet to guard against damage. Nail strengtheners and moderate length reduce future cracks.
