Some Causes and Features of Hives
Some Causes and Features of Hives
Cause |
Common Features* |
Tests† |
Acute hives (lasting less than 6 weeks) |
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Drugs such as
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Hives can start within minutes after the drug was used and can start up to 48 hours later |
A doctor's examination alone |
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Foods that trigger an allergic reaction (food allergens), such as peanuts, nuts, fish, shellfish, wheat, eggs, milk, and soybeans |
Hives that start within minutes or hours after consumption |
A doctor's examination, particularly the medical history Sometimes allergy skin prick testing |
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Infections (rare causes)
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Fever, chills, and fatigue Symptoms of the particular infection Particularly for parasitic infections, recent travel to a developing country |
Tests depending on the suspected infection (suggested by results of the medical history and examination) Diagnosis confirmed if hives disappear after the infection is eliminated |
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Hives that start within seconds or minutes after an insect bite or sting |
A doctor's examination alone |
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Physical stimuli |
For most stimuli, hives that typically start within seconds or minutes of exposure to the stimulus For pressure on the skin, hives that start within 4–6 hours and affect only the area of the skin pressed For sunlight, hives that affect only the area of the skin exposed to sunlight |
Sometimes a doctor's examination alone Exposure to the suspected physical stimulus to see whether it triggers symptoms |
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Serum sickness |
Hives that start within 7–10 days after injection of May be accompanied by fever, joint pain, swollen lymph nodes, and abdominal pain |
A doctor’s examination alone |
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Substances that trigger an allergic reaction through direct contact with the skin (contact allergens), such as latex or meat |
Hives that start within minutes or hours after contact |
A doctor's examination Sometimes allergy testing |
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Transfusion reactions |
Hives that usually start within a few minutes after transfusion of a blood product |
A doctor's examination alone |
Chronic hives (lasting more than 6 weeks) |
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Autoimmune disorders |
Various symptoms depending on the autoimmune disorder For systemic lupus erythematosus, symptoms may include fever, fatigue, headache, joint pain and swelling, painful breathing, and mouth sores For Sjögren syndrome, dry eyes and dry mouth For urticarial vasculitis, hives that |
For all autoimmune disorders, blood tests to check for abnormal antibodies Sometimes skin biopsy For Sjögren syndrome, a test that estimates the amount of tears people are producing For urticarial vasculitis, skin biopsy |
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Cancer, typically of the digestive organs or lungs, or lymphoma |
Weight loss, night sweats, abdominal pain, cough (sometimes bringing up blood), jaundice, swollen lymph nodes, or a combination |
Various tests depending on the cancer suspected |
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Chronic idiopathic hives (diagnosed when no specific cause is identified) |
Hives that occur daily (or almost daily) and itching that lasts for at least 6 weeks, with no obvious cause |
A doctor’s examination Blood and sometimes other tests, such as skin prick tests and exposure to various triggers, to rule out other causes |
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Drugs (same as those for acute hives) |
Hives that occur in a person who has been taking a prescription, an over-the-counter, or an herbal drug for a long time when there is no other explanation for them |
A doctor's examination Sometimes allergy testing Trial of avoidance to see whether hives disappear after the drug is stopped |
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Endocrine abnormalities such as a thyroid disorder or an elevated level of progesterone (a female hormone) |
For thyroid disorders, difficulty tolerating heat or cold, a slow or fast heart rate, and shaking (tremor) or sluggishness Occurring in women who take birth control pills (oral contraceptives) or hormone therapy containing progesterone or who have hives appearing just before their menstrual periods start and disappearing when periods stop |
A doctor's examination If a thyroid disorder is suspected, a blood test to measure thyroid-stimulating hormone |
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Small red discolorations of the skin that turn into hives and become raised when touched Sometimes abdominal pain, easy flushing, and recurring headaches |
Skin and sometimes bone marrow biopsy Sometimes blood tests to measure levels of substances released when certain immune cells (called mast cells) are activated |
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Physical stimuli (same as those for acute hives) |
For most stimuli, hives that typically occur within seconds or minutes of exposure to the stimulus For pressure on the skin, hives that start within 4–6 hours and affect only the area of the skin pressed For sunlight, hives that affect only the area of the skin exposed to sunlight |
Sometimes a doctor's examination alone Exposure to the suspected stimulus to see whether it triggers symptoms |
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* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present. |
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† Although a doctor's examination is always done, it is mentioned in this column only if the diagnosis can sometimes be made by the doctor's examination alone, without any testing. |
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HIV = human immunodeficiency virus. |
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