What causes hives?

Usually allergic rxn: Usually it is caused by an allergic reaction, like contacting something you're allergic to touch. Consult your physician. Wishing you the best.

Histamine release: Mast cell histamine release cause blood vessels to leak resulting in localized swelling (the bump of hives) & sensory nerves to fire giving the sensation or itching. These nerves trigger a local nerve reflex that increases blood flow (the redness of hives). Hives lasting <6 weeks are usually due to viral infection or allergy to foods or drugs. When >6weeks cause is may autoimmune or benign.

Many causes: There are many causes of hives and these include infections, medications, bee/wasp stings, food allergies, environmental allergies, stress, cold temperatures, and exercise amongst other rarer causes. Oftentimes, hives are idiopathic, meaning no known cause. For further evaluation and management, consultation with a board-certified allergist is recommended.

Mast Cells: A special type of white blood cell (bodily defense system) called a mast cell contains the chemical histamine. When it is released in the and around the skin it causes the local swelling and itching we call hives or urticaria. This release of histamine can be caused by lots things like allergies, cold, exercise and even exposure to sunlight.

Broad answer: The causes of hives is very broad: foods, medications, other medical conditions to name a few. A detailed history is required to elucidate the cause of hives. It is not unusual to not find a cause of hives.

Many causes: There are many causes of hives and these include infections, medications, bee/wasp stings, food allergies, environmental allergies, stress, cold temperatures, and exercise amongst other rarer causes. Oftentimes, hives are idiopathic, meaning there is no known cause. For further evaluation and management, consultation with a board-certified allergist is recommended for evaluation and management.

Everything : There are numerous things that will cause hives. Water, heat, cold, sun, drugs, infection are just a few.

Anything: Just about anything and everything can cause hives. Despite this we never determine the cause in many cases of chronic hives. Treatment is the main approach. For many people the hives eventually go away.

Allergic reaction: But can be associated with acute stress.

Many causes: Hives can be due to many things including: 1. Allergies to pollens, mold, dust, food, drugs and bee stings 2. Infections like hepatitis 3. Autoimmunity 4. Complement deficiency – acquired or hereditary 5. Vaculitis 6. Idiopathic – unknown cause – very common treatment may include antihistamines, steroids, h2 blockers and if very severe, cyclosporine.