Hives are usually caused by an allergic reaction to a:
Hives can also be caused by:
Sometimes you and your doctor won't be able to figure out what caused your hives.
Call an ambulance if you have hives and:
Go to the emergency room or a doctor's office as soon as possible if you have hives and:
See a doctor if you have:
Doctors may not need to treat hives if they go away on their own after a day or two and don't come back. If it's clear what caused the hives, your doctor will have you avoid that substance. To lessen your symptoms, your doctor may:
Ask you to bathe in cool water, not scratch your skin, and wear loose clothes until the hives go away
Give you certain medicines, such as antihistamine or corticosteroid pills to treat the itching, depending on how severe your symptoms are
Ask you to stop taking your medicines, if possible, to see if that helps
Antihistamine pills can make you sleepy, particularly if you're older. Be careful about using them if you have to drive or use power tools. On the other hand, antihistamines may help you sleep at night.