Pernicious anemia is a type of anemia caused by the body's inability to absorb vitamin B12 from the digestive tract. This vitamin is essential for producing red blood cells, which carry oxygen throughout the body. Without enough vitamin B12, the body produces larger, abnormal red blood cells that cannot function properly, leading to symptoms like fatigue, weakness, and pale skin. The condition is often linked to an autoimmune disorder that affects the stomach lining, reducing the production of a protein called intrinsic factor, which is necessary for vitamin B12 absorption. Treatment typically involves vitamin B12 injections or high-dose oral supplements to restore normal levels and alleviate symptoms.