Hives, also known as urticaria, are raised, itchy welts that can appear anywhere on your body. If you’re experiencing these irritating bumps, you’re likely asking, “Why Do I Have Hives?” Understanding the potential causes, from allergic reactions to physical triggers, is the first step towards finding relief.
What are Hives?
Hives are characterized by itchy, raised patches of skin that can vary in size and shape. They can appear suddenly and disappear within 24 hours, often without leaving a trace. When hives occur almost daily for more than six weeks, it is considered chronic hives. Unlike bruises, hives do not leave discoloration or scars. In many cases, especially with chronic hives, identifying a specific trigger can be challenging.
If your hives persist for more than a month or keep coming back, consulting an allergist is recommended. An allergist can help determine the underlying cause of your hives through a comprehensive examination and medical history review. Skin tests and challenge tests may also be necessary to pinpoint specific triggers.
Treatment for hives varies depending on severity, ranging from simple home remedies like cool compresses to prescription medications such as antihistamines, anti-inflammatory drugs, and immune system modifiers.
Is It Hives or Angioedema?
Angioedema is a condition often associated with hives, involving swelling in the deeper layers of the skin. It can be triggered by allergic reactions, medications, or hereditary enzyme deficiencies. Symptoms that may indicate angioedema include:
- Swelling around the eyes or mouth
- Swelling of hands, feet, or throat
- Difficulty breathing, stomach cramps, or swelling of the eye lining
To accurately identify your symptoms and determine whether you are experiencing hives, angioedema, or both, it is crucial to consult with an allergist. They can provide a proper diagnosis and develop an appropriate treatment plan for both conditions.
Alt text: Raised red hives visible on skin of forearm, illustrating an allergic reaction.
Diagnosis
Sometimes, the cause of hives is clear, such as a reaction after eating peanuts or shrimp. However, in many instances, uncovering the trigger requires careful investigation by both the patient and a healthcare professional. For chronic hives, the exact cause often remains unidentified.
For a single episode of hives, extensive testing is usually not necessary. If a food allergy is suspected, keeping a food diary can be helpful in identifying potential links between your diet and hive outbreaks.
Chronic hives warrant evaluation by an allergist. They will inquire about your medical and family history, home and work environments, pet exposure, and recent medications. Sharing a food diary with your allergist, if you have been keeping one, can also provide valuable clues.
To pinpoint the cause of chronic hives, your allergist may perform skin tests, blood tests, and urine tests. If a food allergy is suspected, skin-prick tests or blood tests can help confirm the diagnosis. Once a trigger is identified, avoidance of that food and related products is typically advised. In some cases, an oral food challenge, a carefully supervised test where you consume a measured amount of the suspected food, might be recommended to observe for hive development. Similarly, if a medication is suspected, drug challenge tests under medical supervision may be conducted. Due to the risk of anaphylaxis, these challenges should only be performed in a medical setting with emergency equipment and medication readily available.
In cases where vasculitis (blood vessel inflammation) is considered, a skin biopsy may be performed and examined by a specialist under a microscope.
Management and Treatment
Researchers have identified numerous factors that can induce hives, including foods, medications, and physical stimuli. Certain illnesses can also manifest as hives. Common causes include:
- Foods: Particularly peanuts, eggs, nuts, and shellfish.
- Medications: Especially antibiotics like penicillin and sulfa drugs, as well as aspirin and ibuprofen.
- Insect stings or bites.
- Physical stimuli: Such as pressure, cold, heat, exercise, or sun exposure.
- Latex.
- Blood transfusions.
- Bacterial infections: Including urinary tract infections and strep throat.
- Viral infections: Such as the common cold, infectious mononucleosis, and hepatitis.
- Pet dander.
- Pollen.
- Certain plants.
Antihistamines are a common treatment for hives, available both over-the-counter and by prescription. They work by blocking histamine, a skin chemical that triggers allergy symptoms like welts. Non-drowsy antihistamines are often preferred due to their effectiveness, once-daily dosage, and minimal side effects. Your allergist may recommend combining multiple antihistamines and using cool compresses or anti-itch creams to alleviate symptoms.
Severe hives may require short-term treatment with prednisone, other corticosteroid medications, or immune modulators to reduce symptom severity.
If you experience tongue or lip swelling or breathing difficulties, your allergist may prescribe an epinephrine auto-injector to carry at all times. These are early signs of anaphylaxis, a life-threatening allergic reaction. Epinephrine is the only treatment for anaphylaxis. If you develop these symptoms and don’t have your injector nearby, or if symptoms don’t improve after use, call 911 or go to the emergency room immediately. Emergency services carry epinephrine and can provide rapid treatment. Emergency room follow-up is always recommended after using an auto-injector.
If a hive trigger is identified, the best approach is to avoid or eliminate it:
- Foods: Avoid confirmed food allergens.
- Rubbing or scratching: Use gentle soaps. Frequent cool baths can reduce itching and scratching, as these can worsen hives.
- Constant pressure: Wear loose clothing to alleviate pressure hives.
- Temperature: For cold-induced hives, avoid swimming alone in cold water and always carry an epinephrine auto-injector. Protect yourself from cold air with warm clothing and a scarf over your nose and mouth in cold weather.
- Sun exposure: Wear protective clothing and sunscreen.
- Medications: Inform your doctor or pharmacist immediately if you suspect a medication is causing your hives.
Alt text: Allergist performing a skin prick test on a patient’s back to identify potential allergens causing hives.
Chronic Hives
Chronic hives, lasting longer than six weeks and potentially persisting for months or years, can significantly impact quality of life.
When the cause of chronic hives remains unknown even after thorough investigation, it is termed chronic idiopathic urticaria. “Idiopathic” signifies “unknown cause.” Approximately half of chronic idiopathic urticaria cases are linked to immune system irregularities. Chronic hives can also be associated with thyroid disease, hormonal imbalances, and, in rare instances, cancer. However, even chronic hives typically resolve over time.
Physical Urticaria
Physical urticaria refers to hives triggered by physical factors like heat, cold, or pressure.
Common triggers include:
- Rubbing or scratching: The most frequent cause of physical urticaria. Symptoms appear within minutes at the affected area and usually subside within an hour.
- Pressure or constriction: Delayed pressure urticaria can manifest as red swelling 6-8 hours after pressure application from belts or tight clothing. It can also occur in areas under sustained pressure, like the soles of the feet.
- Temperature change: Cold urticaria is triggered by exposure to cold followed by rewarming. This can be severe, even life-threatening, during rapid body cooling, such as plunging into cold water.
- Increased body temperature: Cholinergic urticaria is caused by elevated body temperature due to sweating, exercise, hot showers, or anxiety.
- Sun exposure: Solar urticaria can appear within minutes of sun exposure.
Vasculitis, or inflammation of blood vessels, can also cause hives. These hives are often more painful than itchy, may leave bruises, and typically last longer than a day.
Don’t let hives control your life. Seek answers and relief by consulting with an allergist to understand “why do I have hives” and develop an effective management strategy.
