What are hives?
Urticaria, commonly called hives, presents as swollen, itchy bumps on the skin. These welts may appear red, pink or match your natural skin tone and can vary in size from a tiny pinpoint to over 10 cm across. Their shapes range from round or oval to ring-like, and individual lesions can last mere minutes or persist for days to weeks. Hives can emerge anywhere on the body, though they most often show up on the trunk, neck, arms or legs. A variety of triggers, most notably allergic reactions, can provoke them, and up to one in five people will experience hives at some point. While usually harmless, hives may signal a more serious allergic event if accompanied by breathing problems. Hives are classified as acute when they resolve within six weeks, or chronic if they continue beyond that. The hallmark signs include:
- Raised, round wheals resembling insect bites
- Lesions with a red border and pale center
- Clusters of welts that fade and recur in new groupings
- Temporary nature, individual spots may come and go over minutes to days or weeks
- Intense itching
What causes hives?
The rash results from your body releasing histamine, a protein intended to fight infections, into the skin. Often, the precise cause remains unidentified. Common factors that may set off hives include:
- Viral, bacterial or parasitic infections
- Autoimmune disorders
- Insect stings or bites
- Contact with certain plants or animals
- Foods (e.g. spicy dishes, additives, caffeine or alcohol)
- Medications such as antibiotics, aspirin or codeine
- Contrast dyes used in medical imaging
- Exposure to cold or hot temperatures, or sunlight
- Physical exertion and sweating
- Emotional stress
Who is at risk?
Anyone can develop hives, but they’re more frequent in individuals with known allergies, those on regular medications or people with ongoing infections or chronic health conditions.
How are hives treated?
Most episodes resolve on their own without intervention. If the rash becomes widespread or turns chronic, over-the-counter antihistamines can help control symptoms; if those fail, your doctor may prescribe stronger options. Self-care measures include:
- Wearing loose, non-irritating clothing
- Avoiding hot showers or baths
- Applying cool compresses to ease swelling
- Taking lukewarm baths with baking soda or colloidal oatmeal to soothe itching
When you’re aware of a specific trigger, steering clear of it can reduce recurrences, though many people have multiple provoking factors.
Complications of hives
Occasionally, swelling extends deeper into the skin layers, a condition known as angioedema. If this occurs around joints, it can feel like arthritis, but it most often affects the face and lips. Should your tongue or throat swell and impede breathing, call emergency services immediately (000). Angioedema can also herald anaphylaxis when food or medication is the culprit.
When should you see a doctor?
Consult your physician if hives persist beyond six weeks or worsen over time. Infants with repeated outbreaks should also be evaluated for possible underlying allergies. In any case of suspected anaphylaxis, hives combined with difficulty breathing or throat swelling, dial ambulance services (000) without delay.