Hives are a common, often allergic, reaction to an offending substance or trigger. This condition is typically not serious, and can affect anyone. In fact, about 20% of people develop hives at some point during their lives. Hives are more common in women than in men. Hives can be triggered by numerous different substances or medical conditions, usually beginning as an itchy patch of skin, and evolving into swollen red welts, or wheals of varying sizes and shapes.
What are Hives?
Hives, also called urticaria, consist of swollen bumps, welts, or dry patches that appear on the surface of the skin. Hives can appear as pale or red patches, and are usually itchy. Symptoms of hives can occur on any part of the skin. Many patients feel a burning or stinging sensation after scratching the affected area. A case of hives can range in size, from as small as the tip of a pen, to as large as a dinner plate. Smaller affected areas can also connect to form even larger welts.
Most cases of hives are the body’s allergic response to certain foods, chemicals, insect stings, or medications. The symptoms of hives are often a result of the release of histamine and other chemicals from mast cells, into the blood, which cause itching and swelling. Although anybody is susceptible to this condition, patients with a history of allergies are more likely to experience hives at some point in their lives.
Some cases of hives occur immediately, or within minutes of exposure to an offending trigger. Other cases of hives present as a delayed reaction, two or more hours after exposure.
When the swelling, bumps, and welts similar to hives occurs on the face – particularly around the eyes, lips, and cheeks – it is most likely angioedema. Angioedema also refers to larger welts that occur deeper beneath the surface of the skin. This is usually slightly more serious than hives, lasts longer, and may cause greater discomfort.
Most hives go away within 24 hours. However, new hives may appear as old ones fade, so an outbreak may last a few days. An instance of hives can be considered acute or chronic. Acute hives usually last less than 6 weeks. Chronic hives last longer than 6 weeks. Some patients with chronic hives find that their condition goes away within a year. Children with hives often outgrow the allergies that are the root cause of their hives.
Some patients have fixed hives, or recurrent episodes of hives occurring in the same spot or spots on their body. Fixed hives are usually due to a reaction from a certain medication (fixed drug eruption), or as a result of getting too much sunlight (fixed solar urticaria). Physical urticaria is a type of hives caused by direct physical stimulation of the skin, with a specific form of this condition known as dermatographism, which is caused after firmly scratching the skin.
What Causes Hives?
Allergies are the most common cause of hives, and include triggers such as:
- Fish (especially shellfish)
- Fruits (especially citrus fruits and berries)
- Food additives
- Food preservatives
- Animal dander
- Insect stings or bites
- Medications (antibiotics such as penicillin and sulfa, aspirin, ibuprofen/Advil/Motrin IB, naproxen/Aleve, blood pressure medications or other ACE inhibitors, painkillers such as codeine)
- Plants (poison oak, poison ivy)
Hives may also be caused by other factors, including:
- Emotional stress
- An illness or other medical condition – including lupus, other autoimmune diseases, and leukemia
- Infections – such as mononucleosis, colds, hepatitis, bacterial infection (urinary tract infections, strep throat), fungal infection
- Excessive sun exposure
- Extreme cold
- Pressure on the skin from sitting too long
- Blood transfusions
Vasculitis, or inflammation of the blood vessels, may also cause hives. Vasculitis-induced hives are typically more painful than itchy, and may produce a bruise on or around the affected area.
Some patients may be at increased risk of hives or angioedema if they have a family history, particularly with immediate family members experiencing the condition. Hereditary angioedema is a rare genetic condition that causes patients to inherit the condition.
Signs and Symptoms of Hives
Symptoms of hives can last from minutes to months, or even years. Patients with hives present with raised, itchy, bumpy skin, or swollen, blistered and red patches on their body.
Swollen patches on the skin are called wheals, and those resulting from hives have clearly defined edges. Wheals can sometimes spread and enlarge, and several wheals may even join together to form a larger wheal. The appearance of wheals can change, disappear, and reappear within minutes to hours.
A simple test for hives is to press the center of a wheal and notice if it turns white. This is known as blanching, and is a common symptom of hives.
Hives do not typically form bruises, and do not leave permanent scars.
Prevention of Hives
Many times, hives cannot be prevented, as they may be a reaction to an accidental exposure. Avoiding exposure to certain known triggers, particularly if you have had hives in the past, can help reduce the chances of suffering from hives.
If you are currently recovering, or have recently recovered from having hives, refrain from wearing tight-fitting clothing, and avoid taking hot baths or showers. Also try to avoid using harsh or scented soaps and laundry detergents, as these actions may cause your hives to reoccur. Thoroughly wash sheets and clothes that may have been exposed to certain allergens or triggers.
Wear warm clothing in cold weather, such as a scarf around your nose and mouth, and layers on your extremities. Similarly, in the sun, wear protective clothing and apply sunscreen.
Treatment of Hives
Hives can be treated depending on the severity and causes of the condition. Many cases of hives are harmless and often resolve on their own.
To relieve the itching associated with hives, it is often helpful to place a cool cloth on the affected area, or to take a cool shower. Taking a cool bath with baking soda or uncooked oatmeal may also provide relief. Many cases of mild hives can be relieved this way. Patients experiencing hives should avoid hot baths or showers, as well as tight-fitting or rough, scratchy clothing, as these may further irritate the skin.
A medical professional can recommend an antihistamine to help alleviate symptoms, which will reduce swelling, redness, and itching. Certain over-the-counter antihistamine medications include loratadine (Claritin), fexofenadine (Allegra), hydroxyzine (Atarax, Vistaril), cetirizine (Zyrtec), or diphenhydramine (Benadryl). Prescription antihistamines include cyproheptadine (Periactin), levocetirizine (Xyzal), and combined H2 blocker antihistamines – ranitidine (Zantac) and cimetidine (Tagamet).
You may also be prescribed corticosteroids (such as prednisone or Medrol), to reduce symptoms. Dapsone is an antibacterial medication that can also be used to treat hives. Autoimmune drugs can also be used to calm an overactive immune system, if the previously mentioned medications do not help to clear symptoms of hives. Another drug used for the treatment of hives includes montelukast (Singulair). Ultraviolet radiation treatment has also resulted in successful treatment of hives in some patients. Patients with hereditary angioedema may also be prescribed blood protein controllers, which can help regulate levels of blood proteins to provide symptom relief. Patients with chronic hives may be treated with a combination of medications. Omalizumab (Xolair) is a biologic drug that is directed against the IgE receptor in human mast cells, which has been approved to treat chronic hives in patients older than 12 years of age.
For more severe episodes of hives, you may be prescribed epinephrine (adrenaline), or given an emergency injection of the medication in the emergency room. Patients with a history of hives often carry an EpiPen with epinephrine for such situations.
When Should I Call a Doctor?
You should contact a medical provider if your hives are causing you severe discomfort. If you have tried several self-care measures, and your hives still persist, a medical professional can help you manage your symptoms.
If a current medication you are taking is causing you to experience hives, consult your doctor right away, as you may need to stop taking the medication.
If you have chronic hives, speaking with a medical provider can help manage your symptoms. Chronic hives may also be associated with thyroid disease, hormonal problems, or even cancer. Your medical provider can help assess your condition.
Emergency Warning Signs
Patients experiencing a severe allergic reaction should seek immediate emergency care. Signs of a serious allergic reaction during an episode of hives include:
- Tongue swelling
- Face swelling
- Difficulty breathing
- Tightness in your throat