Hives are a red, raised, itchy skin rash that is sometimes triggered by an allergen. An allergen is something that produces an allergic reaction.
It is also known as urticaria, welts, weals, or nettle rash.
When an allergic reaction occurs, the body releases a protein called histamine. When histamine is released, the tiny blood vessels known as capillaries leak fluid. The fluid accumulates in the skin and causes a rash.
Hives affect around 20 percent of people at some time in their life.
It is not contagious.
Hives are a rash that appears as an allergic reaction.
Urticaria occurs when the body reacts to an allergen and releases histamine and other chemicals from under the surface of the skin.
The histamine and chemicals cause inflammation and fluid to accumulate under the skin, causing wheals.
Examples of known triggers include:
medications, including some antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ACE inhibitors, used for high blood pressure
foods, such nuts, shellfish, food additives, eggs, strawberries, and wheat products
infections, including influenza, the common cold, glandular fever, and hepatitis B
bacterial infections, including urinary tract infections and strep throat
extreme temperatures or changes in temperature
high body temperature
pet dander from dogs, cats, horses, and so on
cockroaches and cockroach waste
some plants, including nettles, poison ivy, and poison oak
insect bites and stings
chronic illness, such as thyroid disease or lupus
water on the skin
In over half of all cases, people never find the exact cause.
Chronic urticaria may start as an autoimmune response, but why it happens is unclear.
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Antihistamines treat acute hives, but antibiotics may be needed for chronic hives.
Treatment for acute urticaria includes non-sedating antihistamines taken regularly for several weeks.
Antihistamines, such as cetirizine or fexofenadine, help by blocking the effects of histamines and reducing the rash and stopping the itching.
Various antihistamines can be purchased in pharmacies or online.
Some antihistamines cause drowsiness, especially if the user also consumes alcohol. Some are not suitable during pregnancy unless prescribed by a doctor.
Patients with angioedema may need to see an allergist, an immunologist, or a dermatologist. Angioedema can cause potentially serious breathing difficulties.
If there is swelling of the tongue or lips, or if breathing becomes difficult, the doctor may prescribe an epinephrine auto-injector, for example, EpiPen, in case of emergencies.
Patients should avoid known triggers, if possible.
Chronic urticaria can cause long-term discomfort, and sometimes complications can occur.
Treatment is different than that for acute urticaria.
Antibiotics, for example, Dapsone, can reduce redness and swelling.
Omalizumab, or Xolair, is an injectable drug that blocks immunoglobin E, a substance that plays a role in allergic responses. It can reduce symptoms of chronic idiopathic urticaria, a type of hives of unknown origin that can last for months or years.
Those with severe symptoms may need to see a specialist.
Acupuncture may help treat hives, but a systematic review published in 2016 concluded that “Acupuncture might be effective and safe for chronic urticaria in relieving symptoms, based on a low level of evidence.” The authors called for further studies to confirm findings.
Chronic hives can lead to severe discomfort, distress, and possibly depression. Stress, too, can aggravate hives, creating a vicious cycle. Patients who experience symptoms of depression should speak to a doctor.
Anaphylaxis leads to severe breathing difficulties and potential unconsciousness. It is considered to be a medical emergency.