At first glance, it can be difficult to tell if itchy skin bumps are from bug bites or caused by an allergic reaction. Both can cause welts or hives, redness and itchiness, but close inspection of the skin changes can usually help determine the culprit. In addition, allergies can also cause an array of symptoms, sometimes severe ones, that might also impact your lungs, nasal passages, mouth, ears and stomach. Minor cases of hives often resolve without medical intervention, but be sure to see a doctor for ongoing or severe symptoms.
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Allergies and Bites
While bug bites introduce chemicals under the skin that cause itching, swelling and redness, allergic reactions occur when the body treats a substance, or allergen, as an invader -- and an abnormal immune response follows. Allergens such as medications, foods, mold or pollen can trigger a release of chemicals such as histamine, which cause the classic symptoms of sneezing, runny nose, wheezing -- and hives. Also called urticaria, hives caused by allergies are red or skin-colored, raised and often itchy bumps which may occur in clusters, similar to insect bites.
Bug bites and urticaria cause swelling can sometimes look the same, but there are some key differences, according to the American College of Allergy, Asthma and Immunology (ACAAI). Bug bites tend to affect a certain area on the skin and do not move to a different location, while urticaria may appear on any area of the body, and may change in shape, relocate, or temporarily disappear then reappear.
Potential for Severe Reactions
Sometimes distinguishing between bug bites and allergy-related welts can be a bit more challenging. For example, if you are allergic to the venom of the insect that bites you, the bug bite itself can trigger urticaria -- or sometimes a more severe, life-threatening allergic response called anaphylaxis, which require immediate medical attention. Rarely, an allergic response that starts with skin symptoms, regardless of the trigger, can also be an early sign of a more severe allergic reaction.
Minor, short-lived urticaria generally does not need medical evaluation. See a doctor if you have hives that last more than 2 days, if your hives have become open sores, if the hives recur without an obvious cause, or if you have other symptoms such as joint pain, unexplained weight loss, fever, night sweats or swollen lymph nodes. Also, if you experience hives after a bee sting, alert your doctor and seek advice on managing future stings, as the next time your symptoms could be more severe. Alert your doctor to any rashes that are red and target-shaped, or any rashes that are accompanied by a fever. Seek immediate medical attention if you have any symptoms of anaphylaxis, such as difficulty breathing or swallowing, feeling lightheaded or dizzy, or swelling of the lips, throat, face or tongue.
Reviewed by Kay Peck, MPH RD