Causes of Urticaria:
Urticaria or Hives are the result of allergic and non-allergic reactions in the body. But in half of cases, there are no causes of hives. The reason is idiopathic.
In allergic cases, many substances, such as different food items, medications, alcohol, insect bites, temperature changes, external environmental conditions, and cosmetics, are the reason for hive formation.
In non-allergic cases, psychological stress, hormonal changes, and autoimmune conditions etc the main reasons for it.
Food allergens: Gluten-rich foods like wheat, oats, and barley, dairy products, nuts, eggs, soy products, and many vegetables like chilly, pepper, and peas, chicken, red meat, and fish are the most common food items that are responsible for hive formation. Preservatives and artificial color-based food items are also the reason for hives.
Medication: Aspirin, penicillin, anticonvulsant, ibuprofen, NSAIDs, sulfonamides, hormonal pills, few vaccinations are the common drugs for the causes of hives. In some cases, morphine, cocaine, and a few injected drugs (heroin) may be the reason for it.
Synthetic items: Many cosmetic items, perfumes, strong fragrances, deodorants, and scented soap,may cause hives.
Environmental allergens/infections: Many parasites like blastocystis, strongyloidiasis, bacterial, and fungal infections, and contact with pollens, poison ivy, poison sumac, and pet animals can increase the sensitivity of body and hives. In a few cases, insect bites can also be a reason.
Temprature-induced: In many cases, temperature changes are the main causes of hive formation. Exposure to cold and windy conditions is the most common reason. Sometimes exposure to the sun is also responsible for hives. Hives appear within a few minutes of exposure to cold or sun. In some cases, after contact with water mostly during swimming for 10-15 minutes, hives appear. The exact reason behind such urticaria is not due to histamine production but it may be due to contact with chlorine. These hives are sustained for a few minutes to a few hours.
Pressure and exercise-induced: Pressure-induced urticaria is also common type of it. Tight-fitted clothes, belts, tight straps, sitting for long, lying on one side, and standing on hard surfaces are the few common sources of pressure urticaria. These hives mostly appear on the legs, waistline, shoulders, hands, and back. Hives may be continued for a few hours to a few days. In exercise urticaria, hives formation, warmth feeling, itching, discomfort, and sometimes shortness of breath are experienced by some people.
Cholinergic Urticaria: Any activities that provoke sweating like hot water bathing, exercise, stress, fear, or in a warm/humid environment is one of the reasons for such type of urticaria.
Dermatographic Urticaria: This is the most common type of urticaria. In such cases, skin becomes inflamed or raised after scratching, pressing, or rubbing. These hives sustain for few minutes.
Stress: Stress and emotional conditions are the main causative reasons for non-allergic urticaria. Intense emotions, continuous anxiety, and stress can affect your immunity and these psychological factors can be responsible for hives formation.
Autoimmune Hives: In a few autoimmune diseases, where your immunity is disturbed, it may cause hives. Many diseases like rheumatoid arthritis, SLE, lactose intolerance, celiac disease, and autoimmune thyroid disorder etc are few examples.
Idiopathic Urticaria: Half of the urticaria cases are due to unknown reason so it is called idiopathic. Research is still going on such idiopathic reasons.
