Urticaria
Urticaria, commonly called hives, is a skin reaction that produces raised, pale-red welts with a distinct itch. Individual weals typically fade within 24 hours, but new ones can keep appearing for days or even weeks. When the same episodes repeat for six weeks or more, the condition is classified as chronic urticaria.
Key points
- A single weal typically settles within a day, but urticaria can keep producing fresh ones for a week or more at a stretch.
- Shellfish, nuts, eggs, insect stings and viral infections are among many possible triggers, though a cause is often never found in long-standing cases.
- Dengue fever stands out as one infectious cause specifically worth checking for when hives appear unexplained.
- Non-sedating antihistamines such as fexofenadine or bilastine suit daytime use, while older, more sedating options are often reserved for night-time.
What sets it off
Almost anything can act as a trigger: foods (shellfish, nuts, eggs), medicines, insect stings, viral infections, latex, extreme temperatures, and pressure on the skin. Heat and humidity are common aggravating factors, and dengue fever is one infectious cause worth ruling out early. In a fair number of chronic cases no trigger is ever identified.
Controlling the itch
First-line treatment centres on antihistamines. Non-sedating options such as fexofenadine and bilastine are generally preferred for daytime use. Older antihistamines like hydroxyzine and cyproheptadine cause more drowsiness and are often used at night or when sedation is acceptable. A full overview of available options sits under allergy relief.
When to seek urgent help
Seek medical attention immediately if hives are accompanied by swelling of the throat or tongue, difficulty breathing, or a drop in blood pressure. These signs point to anaphylaxis, which is a medical emergency.