Which of the following is a common symptom of an allergic reaction?

A common symptom of an allergic reaction is a tingling sensation in the mouth. This symptom can occur when a person is exposed to an allergen, such as certain foods, medications, or insect stings. The tingling sensation often indicates that the body is reacting to a foreign substance, leading to the release of histamines and other chemicals that cause various physiological responses. This response can manifest in different ways depending on the severity of the allergy and the specific allergen involved.

The other choices do not typically relate to allergic reactions. Increased energy levels and improved digestive health are generally not associated with allergies but rather with other conditions or general well-being. Flushed skin can occur in various situations, but it is often more closely linked to other causes rather than specifically indicating an allergic reaction. Therefore, the tingling sensation in the mouth stands out as a direct and relevant symptom of an allergic reaction.