• Chronic: Hives for ≥ 6 weeks
  • Spontaneous: not from an allergy
  • Urticaria: Hives (raised, red itchy bumps/welts)
  • Often associated with Angioedema: Swelling (like deeper hive, beneath skin)
  • CSU is a benign (not dangerous, just annoying) medical condition


  • CSU is THE most common cause of chronic hives in adults (>95% of cases)
  • CSU is NOT caused by allergies
  • “Idiopathic” a bad name (do know cause):
    • ~50% patients with CSU have an abnormal antibody
    • Antibodies are proteins that are normally made to fight infection
    • Instead of fighting infection, this antibody causes hives
  • Triggers: stress (emotional or physical), colds, fever, infection, heat, exercise, pressure,  NSAIDS (group of anti-inflammatory medication such as Aspirin, Motrin, Ibuprofen, Aleve, Naproxen), Opiates (such as codeine, morphine), alcohol
  • The above are POSSIBLE triggers therefore if they are not causing you problems, don’t worry about it.
  • Triggers can make the hives worse but are NOT the cause of the hives

How long does it last?:

  • Variable: Lasts months to years. Average 3-5 years
  • When the hives disappear, they can come back months to years later


  • Antihistamines regularly (take every day to prevent hives)
    • Antihistamines are safe to take long term
      • Reactine (Cetirizine) 10mg-40mg once/day
      • Aerius (desloratidine) 5mg-20mg once/day
      • Allegra (Fexofenodine) 120mg-240mg once/day
      • Claritin (Loratidine) 10mg-40mg once/day
      • Blexten (Bilastine) - by prescription
      • Rupall (Rupatadine) - by prescription
      • Xolair (omalizumab, anti-IgE) - injection prescribed by specialist
      • All the above antihistamines are 24hr (once/day)
  • If necessary, there are other medications that also work

 *** Created by Dr. Ellie Tsai MD, FRCPC Kingston Allergy and Asthma 613-546-6673***

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