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Hives are flat red welts that can appear anywhere on the skin and are usually itchy. Hives often occur as an allergic reaction to something eaten or ingested or something that has contacted the skin. They can also occur due to stress or autoimmune diseases.
What are hives?
Hives, or urticaria, are flat red welts that can appear anywhere on the skin and usually itch. Hives often occur as an allergic reaction to something eaten or something that has contacted the skin. Foods, medicines, and plants are common causes, but sun exposure, stress, infections, and autoimmune diseases have also been known to cause hives.
Symptoms include an itchy, stinging pink rash of slightly swollen skin. The rash may wax and wane in severity. Acute hives typically resolve within six weeks, but chronic hives (urticaria) can persist for months or years.
Hives often resolve on their own, especially in children. Otherwise, treatment for acute hives involves oral antihistamine medications to help relieve the itching and stinging. Chronic hives that do not improve with antihistamines may be treated additionally with corticosteroids, antibiotics, and other stronger medicines. A study found that 35% of people with chronic hives, are symptom free within one year, with another 29% having some reduction of symptoms.
You can safely treat this condition on your own as long as you does not develop trouble breathing. Any antihistamine (like Zyrtec, Clarinex, etc) works.
Hives are common and can be experienced by anyone for a multitude of reasons. Hives affect about 20 percent of people at some point in their life. Persistent hives should be evaluated by a medical provider in order to ensure the reaction is not dangerous, as well as to provide options for symptom relief. The diagnosis of hives is made through patient history, physical examination, blood tests, and sometimes allergy testing.
The main symptom of hives includes a pink or red skin rash that can be described by the following details.
- The rash may be slightly raised
- Patches of rash: These may connect to each other.
- Wax and wane: The rash will often resolve in one spot over 24 hours but then appear elsewhere.
- Move around: The rash may be migratory.
- Vary in size: The rash can range from as small as a pen tip to as large as a dinner plate.
- May itch, sting, or hurt
- Onset: Hives may occur within moments of a trigger or start several hours later.
- Acute urticaria: The acute form occurs in 70 percent of cases and lasts for less than six weeks. It is usually due to an allergy.
- Chronic urticaria: The chronic form occurs in the remaining 30 percent of cases and lasts for more than six weeks, and is usually due to unidentifiable or autoimmune causes.
Hives are sometimes associated with angioedema, a potentially dangerous condition needing immediate medical attention and that involves:
- Lip swelling
- Eyelid swelling
- Throat and tongue swelling: This may lead to difficulty with breathing, which is a medical emergency.
- Abdominal pain: Cramps may come and go due to intermittent swelling in the intestines.
- Genital swelling
What causes hives?
Hives result from immune cells. Mast cells and basophils are two types of immune cells that play important roles in fighting foreign substances (such as infection and cancer), regulating blood flow to damaged tissue, and wound healing. These cells also release substances into the skin that cause blood vessels to dilate. Blood vessel dilation and white blood cell responses lead to swelling of the skin experienced with hives. These substances that are released include histamine, bradykinin, and kallikrein. Mast cell activation can be caused by:
- Immune-mediated activation: IgE antibodies bind to mast cells due to an allergy (i.e., Type I hypersensitivity reaction) or autoimmune disorder.
- Non-immune mediated activation: Drugs may directly activate mast cells or act on other chemical signals that then lead to mast cell activation. Physical or emotional stress may also lead to the release of chemical signals that then activate mast cells.
Common allergic triggers of hives, which cause most acute cases, include:
- Foods: Including fruit, milk, eggs, nuts, soybeans, and shellfish
- Medicines: Such as aspirin, NSAIDs (e.g., ibuprofen/Motrin, naproxen/Aleve), opioids, antibiotics, some blood pressure medications (such as lisinopril)
- Blood transfusions
- Insect bites and stings
- Animal saliva and dander
- Environmental irritants: Such as pollen, dust, and mold
Other triggers that can also cause hives include the following.
- Infections: These may arise from viruses (such as hepatitis, HIV, enterovirus, and EBV, the virus that causes mono), parasites (Giardia, Schistosomiasis), bacteria (such as urinary tract infections, streptococcus, and H. pylori), and fungi.
- Autoimmune diseases: Such as lupus, inflammation of the blood vessels (vasculitis), Sjogren syndrome, and thyroid disease
- Certain cancers: Such as gastrointestinal cancer, lung cancer, and lymphoma
- Sunlight (solar urticaria)
- Extreme hot or cold temperatures
- Pressure: For example, from sitting for a prolonged period or wearing a tight wristband
- Scratching the skin
Treatment options and prevention for hives
If you experienced hives after starting a new medicine, eating a food that isn't typically part of your diet, or being exposed to an animal or environment that is unusual for you, avoid future exposure to these possible triggers. To alleviate hive symptoms that you have not pinpointed the cause of, there are also several methods of treatment that may be effective, such as over-the-counter medications, prescription medications, and lifestyle modifications.
Antihistamine medications are often effective at reducing itching and swelling. They work best when taken regularly, rather than only as needed.
- Newer antihistamines: These are options that block the H1 receptor, such as cetirizine (Zyrtec), fexofenadine (Allegra), and desloratadine (Clarinex) which can be taken daily and have minimal side effects.
- Older antihistamines: Diphenhydramine (Benadryl) is effective, but older antihistamines often have side effects such as tiredness. These may be most helpful when taken before bedtime.
- Topical antihistamines and steroids are not effective for hives
If your hives persist for more than two days and are not responsive to over-the-counter medications, your physician may offer additional treatments, such as:
- Additional H1-blocking antihistamines: Your physician may recommend increased doses, combination treatment with older and newer antihistamines, or prescription antihistamines, such as hydroxyzine.
- H2-blocking antihistamines: Famotidine (Pepcid) and ranitidine (Zantac) may be helpful.
- Leukotriene receptor antagonists: Montelukast (Singulair) and zafirlukast (Accolate), for example, may be helpful in certain cases.
- Tricyclic antidepressants: In addition to their mood-related effects, these medications, such as doxepin, also have high-potency antihistamine activity.
- Immunomodulatory therapies: These may be recommended by allergy and immunology specialists in severe cases that do not improve with the treatments listed above. Immunosuppressive therapies sometimes used for hives include omalizumab (Xolair), which is an injection of antibodies, as well as cyclosporine and tacrolimus.
Small lifestyle changes may help reduce exacerbations of hives. These include:
- Avoid known triggers
- Wear light, loose-fitting clothing
- Take soothing cool showers: You can also place cool cloths on your hives.
- Avoid scratching your skin
- Avoid harsh soaps
- Avoid strong mid-day sunlight and apply sunscreen before going outside
When to seek further consultation for hives
If you have difficulty breathing or swelling of the lips, eyelids or tongue
Difficulty breathing and facial swelling may be the first signs of a severe reaction that could progress rapidly if not treated immediately. If you have signs of hives and develop any respiratory distress, call 911 immediately.
If your hives are severe and interfere with sleeping or daily activities
If your hives are so uncomfortable that they interfere with your daily life, seek medical attention to find out how to better control your symptoms.
If your hives do not improve within a couple days
Many cases of hives resolve within 48 hours. If your hives persist, then medical attention is warranted to evaluate for any deeper underlying medical problem.
Questions your doctor may ask to determine hives
- Is your rash raised or rough when touching it?
- Is your skin change constant or come-and-go?
- How long have your skin changes been going on?
- What color is the rash?
- Which, if any, of these statements describe your raised patch of skin?
Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.
- Schaeffer P. Acute and chronic urticaria: Evaluation and treatment. Am Fam Physician. 2017 Jun 1;95(11):717-724. AAFP Link
- American Academy of Dermatology. AAD Link
- Page EH. Urticaria (hives; wheals). Merck Manual Professional Version. Merck Manuals Professional Version Link
- Chronic hives symptoms & causes. Mayo Clinic. Published March 6, 2018. Mayo Clinic Link