Generally, hives are caused when your body releases the chemical histamine in reaction to something, often in response to an allergic reaction.
Some causes of hives include:
- Food -- One of the most common causes of hives is food. Some foods are more likely to cause an allergic reaction than others are. In fact, 90 percent of hives are caused by milk, soy, eggs, nuts, shellfish or wheat. Other common triggers include chocolate and food additives like sulfites and salicylates. If you have a food trigger, you can simply eliminate it from your diet.
- Medications -- Like food, medications are common culprits of hives, and some are more apt to cause allergies than others are. Common triggers include painkillers like ibuprofen, aspirin and codeine. Other offenders include certain antibiotics and blood pressure medications. If you have an allergic reaction to a medication you are taking and you get hives, talk to your doctor before deciding what action to take.
- Outside sources -- Hives caused by outside influences like exercise, sun, cold or heat are called physical urticarias. If you get this kind of hives, you'll see the bumps within an hour of exposure.
- Other existing conditions -- If you're already suffering from other allergies, an infection or an existing disease, you could develop hives as an offshoot of that condition [sources: Mayo Clinic, American Academy of Dermatology, American Academy of Allergy, Asthma & Immunology, WebMD].
In as much as there are many possible causes for hives, there also are many treatments for it. To discover what treatments work best for different kinds of hives, read on.