Allergic Reactions: This is a major cause. Substances that can trigger allergic reactions and hives include:
* Foods: Peanuts, tree nuts, shellfish, eggs, milk, soy, wheat, fish
* Medications: Penicillin, aspirin, ibuprofen, and many others
* Insect stings/bites: Bees, wasps, mosquitoes, ants
* Latex: Found in gloves, balloons, and other products
* Pollen: A common allergen leading to seasonal hives
Non-Allergic Factors: These aren't true allergies, but they still trigger histamine release:
* Infections: Viral infections (like colds or the flu), bacterial infections, parasitic infections
* Physical stimuli: Heat, cold, pressure, sunlight, vibration (cholinergic urticaria)
* Stress and anxiety: Emotional stress can trigger histamine release.
* Autoimmune diseases: Conditions where the body attacks its own tissues.
* Certain medical conditions: Thyroid problems, lupus, and others.
* Exercise: Exercise-induced urticaria.
* Specific medications (even without allergy): Some medications can trigger hives as a side effect, even if you aren't allergic.
* Food additives: Certain food colorings, preservatives, and other additives can be triggers.
Idiopathic Urticaria: In many cases, the cause of hives is unknown, even after thorough investigation. This is called idiopathic urticaria.
In short: Hives are a complex reaction with a variety of potential causes. If you experience hives frequently or severely, it's crucial to consult a doctor or allergist to determine the underlying cause and receive appropriate treatment. They can help identify potential triggers and recommend treatment options such as antihistamines or other medications.