The short explanation
Itchy, raised, red or pale swellings that appear and fade within hours, moving around the body, are typical of hives, also called urticaria. They happen when certain cells in the skin release histamine and other substances, which leak fluid into the skin. Many people expect a clear food trigger, but often no single cause is found. When hives keep coming back for more than about six weeks, it is called chronic urticaria. Common contributors include infections, stress, some painkillers, heat, pressure on the skin from tight clothes, and sometimes thyroid or other immune conditions. A doctor can suggest treatment to control the itching and reduce flares, and may do some blood tests depending on your history.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- Keeping a simple diary of when hives appear, what you ate, medicines taken and activities can help your doctor spot patterns.
- Hot showers, tight clothing and scratching can worsen hives.
- Hives with swelling of the lips, tongue or throat, or difficulty breathing, is a different and urgent situation.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This cannot tell you what is causing your rash. A doctor needs to see the rash, or photos of it, and ask about your history.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Is this urticaria?
- What tests, if any, do I need?
- What can I use to control the itching at night?
- Could any of my medicines be a trigger?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Emergency — call 112 now
- Call 112 or go to the nearest emergency department if you develop swelling of the lips, tongue or throat, difficulty breathing, or feel faint.
Book an appointment soon
- See a doctor within a few days if hives keep coming back or disturb your sleep.
Raise it at a routine appointment
- Book a routine appointment with a dermatologist if hives have lasted for several weeks.
Sources
The evidence this explanation is built on.
- Skin conditions MedlinePlus (US National Library of Medicine)
- Eczema MedlinePlus (NIH)
- Underactive thyroid (hypothyroidism) NHS
Who wrote and reviewed this
Every AskHer answer names its author. A clinically reviewed answer also names the clinician who signed it off — if no clinician is named below, it has not been clinically reviewed.
- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
Substantive changes are listed, not quietly edited away.
No corrections have been made since this answer was first published.
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