Vitamin B6 Deficiency
If a person has a red and sore tongue tip, the reason could be a deficiency of vitamin B6, niacin or iron in the body. If any of these essential nutrients is lacking in the diet, a person might get a sore red tongue tip. To overcome this deficiency, nettle teas or dandelion teas should be included in the diet, along with vitamin B6 rich foods such as brown rice, avocados, buckwheat, beet root, and sunflower seeds.