Regular exposure to chemicals and harsh environments can make nails brittle and likely to split. Fungal infections and hypothyroidism, which lowers hormone production, can also cause splitting. If you also notice weight gain, fatigue, or depression, hypothyroidism could be to blame. Split nails may signal a lack of biotin, protein, or iron. Frequent hand washing, cleaning products, and cold, dry air can weaken nails. Wearing gloves, moisturizing, and eating a balanced diet can help prevent these problems. Nail strengtheners and keeping nails at a reasonable length can also reduce splitting and cracking.
