| What
causes urticaria is more difficult to answer than what happens
during urticaria, as we described on the earlier page. In
almost half the cases we know what causes or induces urticaria;
and half the time, the patients or we have no clue as to its
exact causation.
We shall try to examine some of the most common
exciting factors known to induce urticaria, which may be grouped
as:
Allergens: A large number of allergens have
been identified as causative agents for some cases of urticaria.
It may be noted that urticaria is an individual hypersensitivity
and the following factors may not cause urticaria in all urticaria-prone
individuals.
Food allergens:
Milk, cheese, egg, protein products, wheat, cereals, certain
daals as used in India, peas, orange, fish, chicken, etc.
Synthetic and natural food additives and artificially-flavored
food articles.
Urticaria and alcohol:
True anaphylactic reactions to alcohol (ethanol) are rare
and most reactions to ingested alcoholic beverages are secondary
to other chemicals in the beverage such as metabisulfite,
papain, dyes or yeasts. However, there are reports of true
allergic reactions in which the offending agent was shown
to be the ethanol itself.
Generally the symptoms of anaphylaxis occur
in such patients following the ingestion of beer and/or wine.
Urticarial rashes have been reported with ethanol ingestion;
and hives on contact with ethanol have also been reported
for some patients.
Environmental factors:
Exposure to pollen, house-dust, buffalo dander, fungi, change
in temperature, etc. are known exciting factors. Extreme cold,
heat, pressure may also induce urticaria.
Drugs:
The major cause for urticaria are man-made drugs such as antibiotics
(Penicillin), anti-inflammatory drugs (aspirin, indomethacin),
vaccinations, foreign sera, hormonal preparations, contraceptive
pills, etc. Animals treated with penicillin excrete a small
amount of it in the milk sufficient to cause urticaria in
sensitive individuals.
Urticaria and cocaine:
There have been reports of morphine-induced hives in some
people. Bronchospasm may occur in some patients who smoke
cocaine or in those who inject heroin. This may occur more
often in patients who have a previous history of asthma. Hypersensitivity
pneumonitis to cocaine has also been described and is associated
with elevated levels of IgE.
Infections and infestations:
Insect bites, Fungal, protozoal, frequent bacterial infections
(Urinary tract), viral infections (Hepatitis), helminthiasis
(worm infestations such as round worms, tapeworms), etc. are
factors known to cause urticaria. Domestic contact with the
pet animals should be examined as cause for urticaria.
Synthetic products:
Use of personal products such as deodorant, perfume, and talcum
powder, cosmetic products, animal derivatives, and similar
synthetic substances may induce this disorder.
Emotional factors:
Especially in chronic, recurring cases of urticaria the role
of emotional factors must be examined. Emotional stresses
may directly or indirectly make on susceptible to develop
a tendency to urticaria. The psychological factors may work
as exciting, aggravating or maintaining cause.
Systemic and general disease:
Urticaria in some cases may present as a sign of other systemic
or general internal disease such as hormonal disorders (hyperthyroidism),
SLE, polycythaemia, reticuloses, etc. In certain variety of
malignancies (cancer) urticaria may present as a precursor.
Idiopathic cause:
No list of causation is complete without adding a paragraph
of 'Idiopathic' which simply implies causes which are unknown.
What
is Urticaria ?|Classification
of Urticaria|Chronic
Idiopathic Urticaria|Cholinergic
Urticaria|
Cold
Urticaria| Urticaria
causes|Traditional
Chinese Medicine and Urticaria|Pressure
Urticaria|
Solar
urticaria
|
