Allergic sore reactions

Does allergic reactions cause sore in the mouth
 
Allergic reactions can cause ulcers in the mouth. However, there are many other causes of oral ulcers. These can include infections, inflammatory conditions, vitamin deficiencies (particularly B12), aphthous ulcers etc. Trauma can also cause ulcers in the mouth. If you have ulcers in the mouth, you should get examined by a doctor to try and find out the cause of ulceration. In the meantime, you could try taking tablets of Vitamin B12 and folic acid along with use of a mouth ulcer gel while eating if it is painful.