Lip balm won't fix this. Called Angular Cheilitis, these painful splits are often caused by fungus thriving when you're low on Iron or Vitamin B2. Eating B rich foods like eggs, spinach, or Did you know your lips can indicate nutrient deficiencies? Dark lips, dryness, irritation, or cracks may signal low levels of essential vitamins and minerals. Vitamin B12 deficiency may cause darker or pigmented Angular Cheilitis: What Is It, Causes, Treatment, and More Osmosis Best Vitamins for Common Symptoms Natural Deficiency Vitamin B12 deficiency: Lip symptoms can include dryness, redness or angular cheilitis Express.co.uk