2017 HCHB_digital

Urticaria (Hives)
Urticaria refers to a group of skin disorders characterised by weals (also
called hives) or angiodema, or both weals and angiodema forming on the
skin. There are several different types of urticaria. Weals (also spelt wheal)
may last from a few minutes to several hours and are pale or skin-coloured
superficial swellings, usually surrounded by erythema (redness). Weals are
generally itchy, 1–2cm in width, and may merge together to form a map-like
pattern or one giant patch. The term urticaria is derived from the Latin word
for stinging nettle, Urtica dioica.
Occasionally, the surface weals may be accompanied by angioedema – which
is a swelling beneath the skin that usually occurs around the facial area (ie, eyes
and lips) but may also be present on the hands, feet, and throat. Angiodema may
progress to anaphylaxis; symptoms include breathing and swallowing difficulty
and shock (see Allergies). Urgent medical advice must be sought. Angioedema
may also occur without weals.
Urticaria can occur anywhere on the body but is mainly found on the trunk,
arms and legs. Sometimes the rash can change shape and disappear from one
place, only to reappear a few hours later somewhere else. The underlying chemical
responsible for urticaria is histamine. Most cases of urticaria resolve within a few
days although, occasionally, a person will have hives for many months or years.
Acute urticaria
Acute urticaria refers to a rash that lasts for less than six weeks. The rash may be
triggered by an allergy or another non-allergic cause. Mast cells and white blood
cells in the skin release histamine, which causes small blood vessels to leak fluid
which pools to form weals.
In acute urticaria due to an allergic cause, the substance responsible is usually
ingested, inoculated, or inhaled, though in some people skin contact with the
allergen may be enough to set off the urticaria (eg, latex). The most common
allergic causes of urticaria are:
• bee or wasp stings
• foods – particularly nuts, fish or shellfish, eggs, tomatoes, eggs, berries, milk,
strawberries and kiwifruit
• latex
• medicines – almost any type of medicine, either prescription or over the
counter, although antibiotics are the most commonly implicated.
Most cases of urticaria are NOT due to allergy, and can occur without previous
exposure. Non-allergic causes of acute urticaria include:
• contact with irritating plants (eg, thistles, stinging nettle) or stinging jellyfish
• infections – such as viral upper respiratory tract infections (eg, colds, sinusitis),
Candida infections, dental abscesses, Helicobacter pylori, viral hepatitis
• non-allergic food reactions – common examples include salicylates in fruits,
azo-dye food-colouring agents, benzoate preservatives, and histamine due to
bacterial decomposition in fish (eg, scombroid fish poisoning)
• non-allergic release of mast-cell granules, which can occur with opiates (eg,
morphine, codeine) and radio-contrast agents
• serum sickness – as a result of a blood transfusion, viral infection or medicines.
TREATMENT OPTIONS
Category Examples Comments
Oral antihistamines
Topical anti-itch products
Natural / herbal products /
supplements
Non-sedating
[PHARMACY ONLY MEDICINE]
eg, cetirizine (Razene, Allerid-C, Histaclear,
Zetop, Zyrtec tablets & liquid), desloratadine
(Aerius Tablets), fexofenadine (Arrowcare
Fexofast*, Hayfexo, Fexoclear, Telfast
180*, Telfast Oral Liquid For Kids, Xergic),
levocetirizine (Levrix), loratadine (Loraclear,
Lorafix)
Sedating
[PHARMACIST ONLY MEDICINE]
eg, dexchlorpheniramine (Polaramine),
promethazine (Phenergan, Allersoothe)
[PHARMACY ONLY MEDICINE]
eg, Anthisan Cream
Vitamin C
Aloe vera gel
These help to control total body itch and wheals. Try and eliminate the underlying cause (eg,
food, medication).
Oral antihistamines are more convenient than topical antihistamines when itch affects the
whole body area.
Generally non-sedating medicines do not cause drowsiness; however, some people may be
more sensitive than others. Warn about the risks of driving or operating machinery if they do
get drowsy.
Similar to non-sedating antihistamines (above); however, these medicines can be quite
sedating. May be useful when taken at night to improve sleep quality if itching is severe.
Warn about the sedating effects and risks of driving or operating machinery while
taking these medicines and to avoid alcohol (see Reference Section, OTC Medicine
Precautions). Sedating antihistamines are [PRESCRIPTION ONLY MEDICINES] for children
under two.
Relieves localised itch and inflammation. Good for short-term use (two to three days) on
small localised areas. Some people with sensitive skin may react to excipients in the cream
and develop a contact dermatitis.
Higher doses of vitamin C (ie, 1000mg) may help reduce histamine levels.
Aloe vera has a cooling, soothing action.
Products with an asterisk have a detailed listing in the Itchy Rash and Urticaria section of OTC Products, on page 266.
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Page 158 HEALTHCARE HANDBOOK 2017-2018 Common Disorders