Cracking on both sides of the thumb may be due to eczema, dry skin, ringworm, etc. 1. Eczema: Inflammatory skin reactions caused by internal and external stimulation of various factors chronic eczema may cause dry skin, dry cracks, may lead to cracks on both sides of the thumb. 2. Dry skin: for example, often live and work in a dry environment, can cause dry skin, skin hyperkeratosis caused by cracked thumbs on both sides. 3. Ringworm: Fungal infections cause superficial skin infections and inflammation of the hand skin, of which the scaly keratinized ringworm, can also cause cracked thumbs on both sides. Thumbs cracked on both sides, there may be other reasons, it is recommended to go to the hospital for examination, to clarify the cause of the disease, and follow the doctor’s instructions for treatment.