Hives — also known as urticaria (ur-tih-KAR-e-uh) — is a skin reaction that causes itchy welts, which can range in size from small spots to large blotches several inches in diameter. Hives can be triggered by exposure to certain foods, medications or other substances.
Angioedema is a related type of swelling that affects deeper layers in your skin, often around your eyes and lips. In most cases, hives and angioedema are harmless and don't leave any lasting marks, even without treatment.
The most common treatment for hives and angioedema is antihistamine medication. Serious angioedema can be life-threatening if swelling causes your throat or tongue to block your airway.
Most hives go away within 24 hours. Chronic hives can last for months or years.
Angioedema is a reaction similar to hives that affects deeper layers of your skin. It most commonly appears around your eyes, cheeks or lips. Angioedema and hives can occur separately or at the same time.
Signs and symptoms of angioedema include:
Large, thick, firm welts
Swelling and redness
Pain or warmth in the affected areas
When to see a doctor
You can usually treat mild cases of hives or angioedema at home. See your doctor if your symptoms continue for more than a few days. Seek emergency care if you feel your throat is swelling or if you're having trouble breathing.
Hives and angioedema can be caused by:
Foods. Many foods can trigger reactions in people with sensitivities. Shellfish, fish, peanuts, tree nuts, eggs and milk are frequent offenders.
Medications. Almost any medication may cause hives or angioedema. Common culprits include penicillin, aspirin, ibuprofen (Advil, Motrin IB, others), naproxen (Aleve) and blood pressure medications.
Common allergens. Other substances that can cause hives and angioedema include pollen, animal dander, latex and insect stings.
Environmental factors. Examples include heat, cold, sunlight, water, pressure on the skin, emotional stress and exercise.
Underlying medical conditions. Hives and angioedema also occasionally occur in response to blood transfusions, immune system disorders such as lupus, some types of cancer such as lymphoma, certain thyroid conditions, and infections with bacteria or viruses such as hepatitis, HIV, cytomegalovirus or Epstein-Barr virus.
Genetics. Hereditary angioedema is a rare inherited (genetic) form of the condition. It's related to low levels or abnormal functioning of certain blood proteins that play a role in regulating how your immune system functions.
Hives and angioedema are common. You may be at increased risk of hives and angioedema if you:
Have had hives or angioedema before
Have had other allergic reactions
Have a disorder associated with hives and angioedema, such as lupus, lymphoma or thyroid disease
Have a family history of hives, angioedema or hereditary angioedema
Severe angioedema can be life-threatening if swelling causes your throat or tongue to block your airway.
To lower your likelihood of experiencing hives or angioedema, take the following precautions:
Avoid known triggers. These may include certain foods or medications or situations such as temperature extremes that have triggered hives or angioedema in the past.
Keep a diary. If you suspect food is causing the problem but aren't sure which food is the trigger, keep a food and symptom diary.
You're likely to start by seeing your family doctor or primary care doctor. However, in some cases when you call to set up an appointment, you may be referred immediately to a skin disease specialist (dermatologist) or to an allergy specialist.
Because appointments can be brief and there's often a lot of ground to cover, it can help to be well prepared. Here are some tips to help you get ready for your appointment and what to expect from your doctor.
What you can do
Write down your signs and symptoms, when they occurred, and how long they lasted. Also, make a list of all medications, including vitamins, herbs, supplements and over-the-counter drugs that you're taking. Even better, take the original bottles and a written list of the dosages and directions.
Write down questions that you want to ask your doctor. Don't be afraid to ask questions or to speak up when you don't understand something your doctor says. For hives and angioedema, questions you may want to ask include:
What is likely causing my symptoms?
Are tests needed to confirm the diagnosis?
What are other possible causes for my symptoms?
Is my condition likely temporary or chronic?
What is the best course of action?
What are the alternatives to the primary approach that you're suggesting?
Do I need prescription medication, or can I use over-the-counter medications to treat the condition?
What results can I expect?
Can I wait to see if the condition goes away on its own?
What to expect from your doctor
Your doctor is likely to ask you a number of questions, such as:
When did you first begin experiencing symptoms?
What did your skin reaction look like when it first appeared?
Have your symptoms changed over time?
Have you noticed anything that makes your symptoms worse or better?
Do your skin lesions mainly itch, or do they burn or sting?
Do your skin lesions go away completely without leaving a bruise or a mark?
Do you have any known allergies?
Have you ever had a similar skin reaction before?
Have you tried a new food for the first time, changed laundry products or adopted a new pet?
What prescriptions, over-the-counter medications and supplements are you taking?
Have you started taking any new medications or started a new course of a medication you've taken before?
Has your overall health changed recently? Have you had any fevers or lost weight?
Has anyone else in your family ever had this kind of skin reaction? Do other family members have any known allergies?
Your doctor will examine your welts or areas of swelling if they are still present and take a careful medical history to identify possible causes. In some cases, your doctor may recommend an allergy skin test. If your doctor suspects hereditary angioedema, he or she may order blood tests to check for levels and function of specific blood proteins.
If your symptoms are mild, you may not need treatment. Many cases of hives and angioedema clear up on their own. But treatment can offer relief for intense itching, serious discomfort or symptoms that persist.
Treatments for hives and angioedema may include:
Antihistamines. The standard treatment for hives and angioedema is antihistamines, medications that reduce itching, swelling and other allergy symptoms.
Corticosteroids. For severe hives or angioedema, doctors may sometimes prescribe an oral corticosteroid drug — such as prednisone — to reduce swelling, redness and itching.
Autoimmune drugs. If antihistamines and corticosteroids are ineffective, your doctor might prescribe drugs used to calm your overactive immune system.
Blood protein controllers. If you have hereditary angioedema, a variety of medications can regulate levels of certain blood proteins and relieve your signs and symptoms.
For a severe attack of hives or angioedema, you may need a trip to the emergency room and an emergency injection of epinephrine — a type of adrenaline. If you have had a serious attack or your attacks recur, despite treatment, your doctor may have you carry a pen-like device that will allow you to self-inject epinephrine in emergencies.
If you're experiencing mild hives or angioedema, these tips may help relieve your symptoms:
Avoid triggers. These can include foods, medications, pollen, pet dander, latex and insect stings.
Use an over-the-counter antihistamine. A nonprescription oral antihistamine, such as loratadine (Claritin), cetirizine (Zyrtec) or diphenhydramine (Benadryl, others), may help relieve itching.
Apply cool, wet compresses. Covering the affected area with bandages and dressings can help soothe the skin and prevent scratching.
Take a comfortably cool bath. To relieve itching, sprinkle the bath water with baking soda, uncooked oatmeal or colloidal oatmeal — a finely ground oatmeal that is made for the bathtub (Aveeno, others).
Wear loose, smooth-textured cotton clothing. Avoid clothing that's rough, tight, scratchy or made from wool. This will help you avoid irritation.