What are common symptoms of an allergic reaction?

Common symptoms of an allergic reaction are primarily linked to the body's immune response to an allergen, which can manifest in a variety of ways. Symptoms like rashes and swelling indicate that the body is reacting to what it perceives as a threat, causing inflammation and changes in skin condition. Difficulty breathing is a serious symptom that can occur due to airway swelling or constriction, often associated with severe allergic reactions known as anaphylaxis. Unconsciousness, while less common, can occur in extreme cases where the body's reaction is severe enough to impact vital functions.

Understanding this context highlights why the symptoms associated with allergic reactions need to be taken seriously, as they can escalate quickly into life-threatening situations if not addressed promptly. The other options present symptoms that may relate to various health issues but do not clearly characterize the typical responses seen in allergic reactions.