Hives, also known medically as urticaria, are characterized by itchy welts that appear on the skin. These welts can vary in size and shape, and while often temporary, they can be a source of significant discomfort. Chronic hives, specifically, are defined by their persistence, occurring almost daily for more than six weeks. A hallmark of hives is that individual welts typically resolve within 24 hours, without leaving bruises or scars. Often, pinpointing a specific trigger for hives, especially chronic cases, proves challenging.
If you’re experiencing hives that last longer than a month or frequently recur, consulting an allergist is advisable. An allergist can conduct a detailed medical history review and physical examination to investigate potential causes. Skin tests and challenge tests may also be employed to identify specific substances that might be provoking your hives.
Treatments for hives range from simple home remedies like cool compresses to alleviate itching, to prescription-strength antihistamines and other medications. These might include anti-inflammatory drugs or medications designed to modulate the immune system, depending on the severity and underlying cause of the hives.
Hives or Angioedema? Recognizing the Difference
Angioedema is a condition often confused with or occurring alongside hives. It involves swelling in the deeper layers of the skin tissue. Angioedema can stem from allergic reactions, certain medications, or even hereditary enzyme deficiencies. Key symptoms that may indicate angioedema include:
- Swelling around the eyes or mouth
- Swelling of the hands, feet, or throat
- Breathing difficulties, stomach cramps, or swelling of the eye lining
To accurately diagnose your symptoms and differentiate between hives and angioedema, seeking evaluation from an allergist is crucial. Allergists are experts in diagnosing and managing both conditions.
Diagnosing the Root Cause of Hives
In some instances, the trigger for hives is readily apparent. For example, a person might develop hives shortly after consuming peanuts or shrimp, clearly indicating a food allergy. However, in many other cases, identifying the cause of hives requires careful investigation by both the patient and their healthcare provider due to the wide array of potential triggers. When hives persist for an extended period, determining the exact cause often becomes difficult.
For isolated episodes of hives, extensive testing is usually not necessary. If a food allergy is suspected, keeping a food diary to track your meals and hive outbreaks can be helpful in identifying potential links.
Chronic hives, however, warrant evaluation by an allergist. The allergist will inquire about your personal and family medical history, substances you are exposed to at home and work, contact with pets or other animals, and any medications you’ve recently taken. If you’ve been maintaining a food diary, sharing it with your allergist will provide valuable information.
To pinpoint the cause of chronic hives, your allergist may recommend skin tests, blood tests, and urine tests. If a specific food is suspected, skin-prick tests or blood tests can help confirm a food allergy. Once a food trigger is identified, avoidance of that food and products containing it is typically advised. In some cases, an allergist might perform an oral food challenge, a controlled test where you ingest a measured amount of the suspected food under medical supervision to observe if hives develop. Similarly, if medication is suspected as the culprit, comparable tests and cautious drug challenges may be necessary to confirm the diagnosis. Due to the risk of anaphylaxis, a severe, life-threatening allergic reaction, these challenge tests must be conducted under strict medical supervision with emergency medication and equipment readily available.
In situations where vasculitis, or inflammation of blood vessels, is considered as a possible cause of hives, your allergist may perform a skin biopsy. The biopsy sample is then examined by a specialist under a microscope.
Managing and Treating Hives: Addressing the Causes
Researchers have made significant progress in identifying factors that can trigger hives, though not all causes are yet fully understood. These triggers can include foods, medications, and substances you come into contact with. Some individuals develop hives simply from physical contact with certain materials. Additionally, various illnesses can also manifest with hives. Here are some of the most frequently identified causes of hives:
- Certain Foods: Particularly common culprits include peanuts, eggs, nuts, and shellfish.
- Medications: Antibiotics, especially penicillin and sulfa drugs, along with aspirin and ibuprofen are known to cause hives in some individuals.
- Insect Stings or Bites: Reactions to insect venom can trigger hives.
- Physical Stimuli: Pressure, cold, heat, exercise, or sun exposure can induce physical urticaria in susceptible people.
- Latex: Latex allergy is a known cause of hives upon contact.
- Blood Transfusions: Reactions to blood transfusions can sometimes include hives.
- Bacterial Infections: Infections like urinary tract infections and strep throat have been linked to hives.
- Viral Infections: Common viral infections such as the common cold, infectious mononucleosis, and hepatitis can also trigger hives.
- Pet Dander: Allergens from pet dander are a common cause of hives for those with pet allergies.
- Pollen: Seasonal pollen allergies can sometimes manifest as hives.
- Certain Plants: Contact with some plants can cause hives in sensitive individuals.
Antihistamines are a primary treatment approach for hives, available both over-the-counter and by prescription. They work by blocking histamine, a chemical released in the skin during allergic reactions that contributes to allergy symptoms, including hives. Non-drowsy antihistamines are often preferred due to their effectiveness, long-lasting action (often once-daily dosing), and minimal side effects. Your allergist may recommend using a combination of two or three antihistamines along with soothing treatments like cold compresses or anti-itch creams to manage symptoms.
Severe cases of urticaria may require short-term treatment with prednisone, a corticosteroid medication, or immunomodulators to reduce symptom severity.
If your hive reaction involves swelling of the tongue or lips, or if you experience difficulty breathing, your allergist may prescribe an epinephrine auto-injector. This device delivers a dose of epinephrine (adrenaline) and should be kept readily available at all times. These symptoms can be early indicators of anaphylaxis, a potentially fatal allergic reaction that impairs breathing and can lead to shock. Epinephrine is the only treatment for anaphylaxis. If you develop these severe symptoms and your epinephrine injector is not nearby, or if symptoms don’t improve immediately after use, call emergency services (911 in the US) or go to the nearest emergency room immediately. Even after using an auto-injector, follow-up emergency medical care is essential.
When the cause of hives is identified, the most effective treatment strategy is avoidance or elimination of the trigger:
- Foods: Strictly avoid foods identified as triggers.
- Rubbing or Scratching: Use gentle soaps and frequent baths to minimize itching and scratching, as these can worsen hives.
- Constant Pressure: Wear loose-fitting clothing to avoid pressure-induced hives.
- Temperature: For cold-induced hives, avoid swimming alone in cold water and always carry an epinephrine auto-injector. Minimize exposure to cold air and protect your face and mouth with a scarf in cold weather. Wear warm clothing when outdoors in the cold.
- Sun Exposure: Use protective clothing and apply sunscreen to prevent sun-induced hives.
- Medications: If you suspect a medication is causing hives, promptly inform your doctor or pharmacist.
Chronic Hives: When Hives Persist
Hives are considered chronic when they last longer than six weeks and can persist for months or even years.
If the cause of chronic hives remains unidentified after thorough medical history review and testing, it is classified as chronic idiopathic urticaria. “Idiopathic” signifies “unknown cause.” Interestingly, approximately half of chronic idiopathic urticaria cases are linked to underlying immune system factors. Chronic hives can also be associated with thyroid disease, other hormonal imbalances, or, in rare instances, cancer. However, even chronic hives often resolve spontaneously over time.
Physical Urticaria: Hives Triggered by Physical Factors
In physical urticaria, hives are directly caused by physical stimuli such as heat, cold, or pressure.
Common triggers for physical urticaria include:
- Rubbing or Scratching: This is the most frequent cause of physical urticaria. Symptoms appear within minutes at the site of rubbing or scratching and typically subside within an hour.
- Pressure or Constriction: Delayed pressure urticaria can manifest as red swelling six to eight hours after pressure is applied, such as from belts or tight clothing. Symptoms can also occur in areas under sustained pressure, like the soles of the feet.
- Temperature Changes: Cold urticaria is triggered by exposure to cold temperatures followed by rewarming. This can be severe and potentially life-threatening if it involves generalized body cooling, like plunging into cold water.
- Elevated Body Temperature: Cholinergic urticaria is caused by an increase in body temperature due to sweating, exercise, hot showers, or anxiety.
- Sun Exposure: Solar urticaria can develop within minutes of sun exposure.
Inflammation of blood vessels, known as vasculitis, can also present with hives. These hives tend to be more painful than itchy, may leave bruises, and often last longer than 24 hours.
Don’t let hives disrupt your life. Seeking guidance from an allergist can provide answers and effective management strategies.
