Result of atherosclerotic plaque blocking one or more of the blood vessels that supply the heart. Can cause chest pain/angina pectoris occurring due to stress of exercise. If blockage completely impedes blood flow to the heart, a heart attack can occur.
It can be caused by insect stings, food, or medicines. It's caused by the release of histamine into your bloodstream and tissues. Histamine is an immune system chemical. Tongue or throat swelling can happen along with an allergic rash (hives), wheezing, diarrhea, and shock (low blood pressure).
If you have an allergy to a certain food you ate, then it is possible the main symptom you feel is tongue swelling. Other causes of tongue swelling are more rare. For example a deficiency in vitamin B12 can cause Glossitis which can result in a swollen, often red tongue. This does not usually happen overnight. Only your doctor can determine the cause of you tongue swelling. Good luck.