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What is Urticaria?
Urticaria is an allergic reaction pattern of the skin,
characterized by eruption of wheals or hives, which are itchy, transient,
reddish and edematous swelling of the skin and mucosal surfaces that
spread by peripheral extension and assume bizzare patterns on the
skin.
Wheals are caused by release of histamine and other
chemical mediators which are released by mast cells which accumulate in
the dermis of the skin as a response to some immunological or non
immunological allergic response in the body.
What are the Types of
Urticaria?
Acute Urticaria: Usually of less than 6 weeks'
duration. In children and young adults, cause identifiable from
history and investigations. It is caused by release of
Immuno-globulin E (IgE) which stimulates the release of chemicals
from the mast cells.
Chronic Urticaria: When the duration of urticaria is
more than 6 weeks, it is known as chronic urticaria. Primarily seen
in middle aged females. It is usually non-igE dependent and ony in
5-20% can we find out a cause in these cases! Hence known as
Chronic Idiopathic Urticaria
Angioedema: A Medical
Emergency!
Angioedema
occurs when the wheals of urticaria affect the subcutaneous
tissue rather than the dermis in normal urticaria.
Angioedema occurs on the face, entire extremities or within a
vital organ system. The eyelids may close down due to edema. When
there is swelling of the face and lips, it is time to get the
patient to hospital as early as possible. Throat swelling or glottal
edema, can cause death due to asphyxia, as the oxygen supply to the
lungs may be entirely cut off following the closure of the
airways due to the
edema!.
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What are the causes of
Urticaria?
Any thing under the sun, including the
sun, can cause urticaria!
And, that sums up the causes of urticaria.
And that also shows why finding the cause in chronic
urticaria is a herculean task.
However, here is a list of common causes of urticaria
that you should look for:
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Medications- Common cause of chronic
Urticaria
Aspirin, non steroidal Anti inflammatory drugs,
cocaine, morphine, codeine, atropine, neomycin, polymyxin B, thiamine
etc
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Toxins -like snake venom, jelly fish, insect
bites, plant contacts and ingestion
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Food and food additives - Citrus fruits,
strawberries, shell fish, eggs, nuts, beer and alcoholic
beverages.
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Water- Aquagenic urticaria: drop like wheals
around hair follicles
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Chemicals- Compound 48/80, polysorbate
80,radiocontrast media,tartrazine,dextran,opioids
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Infections- Often hidden. Dental caries is a
particular suspect. Worm infestations in children. Cystitis, prostatitis
or vaginitis. Urticaria is typically seen in infectious mononucleosus, a
viral infection.
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Physical Agents: Friction, pressure,sweating,
cold,heat, sunlight, vibration
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Endocrine abnormalities:
Hyperthyroidism
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Malignancies: Leukemia,lymphomas, Colon
carcinoma
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Contactants: Any chemical, plant or physical
as above
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Inhalants: Pollens, chemical dusts
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Vasculitis: Systemic Lupus Erythematosus,
Still's disease, Urticarial vasculitis
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Idiopathic: No demonstrable cause detected
despite extensive history taking and investigations. Stress may
be an important factor here.
What type of Investigations should be
undertaken in Urticaria?
Usually in acute urticaria, extensive investigations
are not required. I routinely advice my patients to keep a daily diary of
activities including food taken and timings, to find out any demonstrable
causes. Physical examination is done to exclude ant evidence of
infections(dental caries, fungal nail infections, pyoderma, chronic
discharging sinuses, chronic sinusitis and other systemic
infections.
Chronic Urticaria, however calls for a battery of
investigations, the base minimum being the following:
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Complete blood count
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Absolute eosinophil count
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ESR
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Liver function tests
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Kidney function tests
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Urine analysis
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Stool examination
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Serology for hepatitis B & C
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Thyroid function tests
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Total IgE
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Serology for infectious mononucleosus
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C1 esterase inhibitor deficiency
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Skin biopsy(especially in urticarial
vasculitits)
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Urticariogen challenge test in
physical urticarias, where urticaria can be reproduced when the allergen
is applied to the skin,
for e.g: |
Taking a proper history in Urticaria is
essential
Acute Urticaria:
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When
did it start?
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When
is it more?Home?Work?Club?
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Any
relation to food/drinks?
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Any
medication taken prior?
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Recent
change in environment/travel/habits
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Exposure to pollens and other allergens
Chronic Urticaria
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All
the above questions plus
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Seasonal variations
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Appearance after physical stimuli
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Associated medical disorders
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History of treatment and response
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History of stress
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Dermographism: Blunt stroke will produce wheals. A simple test
to assess the treatment progress as well!
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Photosensitivity test in solar urticaria
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Exercise challenge in cholinergic urticaria
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Ice Cube test in cold urticaria
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Hot water tube test in heat urticaria
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Water immersion test in aquagenic urticaria
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Strap weight test in delayed pressure
urticaria
Tips on Managing
Urticaria
General
Measures
- Patient education:
- Recognition and
elimination of allergens like medications, food, food additives,
contactants etc
- Even previously innocuous
medications and conatactants can develop sensitivity in later
life
- Without frightening the
patient, I inform the patient about the dangers of angioedema and the
first signs of development of angioedema and the need for fast medical
care.
- I always tell my patients
who tell me" Doctor, I have been using this for years": The
allergen may not have changed; but your body and mind is undergoing
changes every second!
- Patients of cholinergic
urticaria are advised to avoid strenuous exercises and sweating
- Cool moist compresses (except
in aquagenic and cold urticarias!) and application of soothing lotions
may help reduce the stinging sensations, but have no effect in
controlling the wheals.
Specific Drug
Therapy
- H1 antagonist antihistamines are the drugs
of choice: Cetrizine and derivatives, terfenadine,loratine etc
- H2 antagonists like cimetidine and
ranitidine are also combined
- In particularly treatment resistant cases
of Chronic Idiopathic Urticaria, I always give the patient a therapeutic
trial of systemic antibiotics and antifungals
- Systemic steroids only in acute
urticarias, after ruling out an infectious focus
- Adrenaline is life saving in angioedema
and can also be used in severe cases of urticaria even without
angioedema.
- Cyproheptadine is particularly effective
in cold urticaria
- Corticosteroids and non steroidal anti
inflammatory drugs are effective in controlling delayed pressure
urticaria, where antihistamines are not effective
- Danazol and stanozolol, by increasing the
synthesis of C1 esterase inhibitor, prevent attacks of hereditory
angioedema
- Recently Ca channel blockers, by their
anti-mast cell activity has been found to be effective
- Ketotifen and doxepine are also effective
in some cases
- Most patients get an exacerbation due to
sudden mast cell degranulation when they start on antihistamines. This
can develop into angioedema and should be carefully watched for. In
severe cases,therefore, I always give the patient a combination of short
acting and long acting antihistamines.
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Dr.Hanish Babu, MD
