Itching is a widespread allergy symptom of contact, respiratory or ingestion sensitivity. Skin tingling or an itchy rash can develop during a number of different types of allergic reactions, of seasonal or perennial causes. Itching can be a warning sign that precedes more serious symptoms, such as anaphylaxis, a total-body metabolic disturbance. Itchy rashes usually fade within a few weeks, unless an underlying skin condition is present.
Hay Fever
Allergic rhinitis, commonly known as hay fever, is a seasonal allergy that can cause itching. According to the Cleveland Clinic, this allergic reaction to airborne pollen grains affects the mucous membranes of the eyes, nose and mouth. After inhaling an allergen such as grass or tree pollen, itchy eyes, nose or throat may be the first allergy symptoms.
Food or Drug Allergy
In addition to causing digestive tract symptoms, allergic reactions to foods or drugs may produce itching. The University of Maryland Medical Center reports that eye itching and an itchy rash or hives elsewhere on the body may result from an adverse reaction to a food or medication. Peanuts, milk and antibiotics are known sources of allergies in some people. Itching symptoms, often accompanied by swelling, may be immediate or arise within an hour or two.
Insect Sting
Bees, wasps, hornets and fire ants all transfer their venom to humans during a sting. An allergic reaction to this substance can induce itching on any area of the body, not just the sting site, according to the Mayo Clinic. Allergy symptoms following insect stings may also include respiratory problems.
Poison Ivy
An itchy rash often appears in spots where the body has come into contact with certain plants, such as poison ivy, poison oak or poison sumac. Itching can be intense and persistent, possibly accompanied by hives and pain. The Mayo Clinic notes that severe reactions may cause skin to bubble and blister, raising the risk for infections from scratching and breaking the skin. Patients should wash clothing or outdoor gear after contact to avoid transferring the plant’s resin and creating a chain reaction of allergic irritation.
Other Contact Allergies
Poison ivy allergy is just one of many forms of allergic contact dermatitis that can cause itching. An itchy rash may be an allergy symptom of contact with rubber, latex and certain chemicals in sensitive individuals. Some metals, such as nickel, in jewelry can cause adverse reactions in certain individuals. The Mayo Clinic also lists contact allergies to cleaning products, cosmetics, perfumes and fabrics among the allergies that can cause itching.
