A taste of blood in the mouth, often described as a metallic or iron-like taste, can be caused by several factors including poor oral hygiene, gingivitis (gum inflammation), nosebleeds, use of iron or mineral supplements, sinusitis, certain medications, infections, and even exercise-related factors like the breakdown of red blood cells in the lungs. Other causes might include stomach issues like acid reflux or ulcers. If the blood taste is persistent or accompanied by other symptoms, consulting a healthcare provider or dentist is advised to assess and address the underlying cause.