Urticaria Overview

Causes | Who can be affected? | Types | Seeking medical consult

When there is a sudden eruption of swollen-looking pale itchy evanescent reddish bumps on your skin which which generally worsen by scratching, it can be urticaria. These plaques, also known as wheals or rash, can be either your body’s sharp reaction to some allergens or other unidentified factors. Urticaria is also known as hives. The rash may last from hours to one to two days generally.

Causes

The cutaneous mast cells have been implicated as major ‘effector’ cells for causes of urticaria.

Immunologic and non -immunologic stimulation of mast cells > Causes  degranulation of mast cells>Release of mediators most important being histamine and more like heparin, proteases, leukotrienes, platelet activating factor and cytokines.> mainly histamine binds to the receptors on the capillaries producing vasodilation and edema and increase permeability to large plasma proteins like albumin which manifest clinically as a wheal/urticaria.

Who can be affected?

Why the triggers cause histamine release is not known. But urticaria can occur across races and ethnicity equally. And acute urticaria occurs equally in male and female population whereas chronic urticaria is more common in women. Generally, it can happen in any age group but chronic urticaria occurs after 40 years or so.

Possible triggers

There are a number of identifiable urticaria symptoms and factors can trigger an attack of urticaria by releasing the histamine like

• Insect stings.
• Allergic reactions.
• Certain medications, diseases, infections.
• Chemicals, latex, nettles.
• Some foods.
• Physical factors like sunlight, heat, cold,

Types

Urticaria diagnosis involves a detailed analysis of the primary trigger factors and understanding the types of urticaria.

• Acute urticaria – rash lasts for about six weeks or less. Maybe due to infections, medications or allergic reaction to some food items.
• Chronic urticaria – rash lasts for a longer period; can affect internal organs; with difficult-to-identify causes.
• Physical urticaria – due to physical stimulus/contact of the skin with the triggers like temperature related, exercise -induced, solar and aquagenic induced.
• Dermatographism – rash occurs when skin is lightly scratched, stroked etc.
• Urticaria due to underlying medical diseases – like urticaria pigmentosa, cutaneous vascultis, serum sickness etc.
• Urticaria due to hereditary causes – like angioneurotic edema,vibratory angioedema, familial cold urticaria .
• Contact urticaria a induced by biologic or chemical skin contact.
• Autoimmune urticaria – its of autoimmune eitolgy.
• Idiopathic urticaria – unknown cause

Seeking medical consult

Sudden outbursts of rash for no apparent reason can be unsettling. Sometimes alarming symptoms can be like

• Breathlessness.
• Dizziness.
• Breathing difficulties.
• Wheezing.
• Sometimes face, lip and tongue may get swollen.

You need to reach for medical care to know why these things happen and how to stop them. If you go to your doctor while you are having the rash, he will look at the rash and want to know your medical history. Lab tests will be ordered and blood and urinalysis will be conducted to know any systemic complications.

Prognosis

Identifying the triggers that cause the histamine release is the first and foremost treatment plan. Antihistamine tablets will be prescribed. Depending on the severity of the attack, epinephrine injections may be given. Avoiding triggers can stop further attacks.

• References

• • Indian Journal of Dermatology, Venereology & Leprology – A comparative study of various therapeutic regimens in urticaria (Amiyakumar Mukhopadhyay, S Nitin Vora, Jayend Dave) view
  • University of Maryland Medical Center – Urticaria view
  • WebMD – Hives & Urticaria view
  • American Association of Dermatology – Hives view
  • British Association of Dermatologists – Urticaria and Angioedema view
  • NHS UK view
  • Emedicine Health – Hives and Angioedeme view