Contact urticaria is a different type of allergy where the reaction starts shortly after contact with the allergen, usually within 10-30 minutes following skin contact. It is referred to as a Type 1 hypersensitivity. It normally settles down within an hour after contact with the causative allergen has stopped.
Recurrent episodes of contact urticaria can lead to dermatitis, termed protein contact dermatitis. This may technically appear just like allergic or irritant contact dermatitis.
Prick tests or blood test measuring seru, specific IgE are used to diagnose contact urticaria. At the SHI, prick testing is most commonly performed in food handlers who describe immediate symptoms or itching when handling a particular food such as fish or chicken. Prick testing for grasses, pollens or mould is not performed at the SHI. For this, referral to an allergist would be required.
Common causes are:
- Natural rubber latex
- Hairdressing bleach (ammonium persulfate)
- Foods such as seafood, meat, chicken, wheat, rye and some fruit and vegetables
- House dust mite
- Malassezia furfur
Latex allergy
Latex allergy is also a form of contact urticaria.
Healthcare workers (HCWs) are one of the occupational groups most commonly affected by latex allergy from the use of latex gloves. Powdered disposable latex gloves increases the risk of latex allergy. The powder facilitates the transfer of the latex allergen to the skin and also aerosolises it, so latex proteins attached to the powder can be inhaled, ingested or enter the skin via cracks and splits in the skin.
Some people with latex allergy can also be allergic to some fruits which have similar proteins to latex, including banana, avocado, kiwi fruit and melon.
People with immediate allergy to substances like latex, hairdressing bleach, wheat and rye may develop systemic symptoms such as asthma. Usually they need assessment by an allergist or an immunologist.
Signs and symptoms of latex allergy:
- An itchy, red rash within minutes of contacting latex
- Hives or welts on the skin
- Runny nose, sneezing and sometimes asthma
- Itchy eyes
- Burning, stinging, itching, tingling and swelling from latex contact on ‘mucous membranes’ lining internal surfaces, like the mouth (from blowing up balloons or gloves worn by dentists), or the genitals (from condoms)
- Rarely, abdominal discomfort from ingestion of latex
The symptoms normally resolve within an hour or two after contact has ceased.
Diagnosis of contact urticaria including latex allergy
Tests used to diagnose contact urticaria include blood tests and a different form of allergy testing, called prick testing. Prick testing is commonly used by allergists to diagnose causes of asthma, hay fever and food allergies. Serum specific IgE tests (formerly called radio-allergo-sorbent test or RAST tests) can also be used to diagnose latex allergy, and are the safest option if severe latex allergy is suspected.
When testing for latex allergy, it is important that the phlebotomist performing this blood test does not wear latex gloves.
Patch testing is not used to diagnose latex allergy.
In addition to latex gloves causing latex allergy, there are many other medical and household products that may contain latex. These may include:
| Reusable rubber gloves | Condoms |
| Rubber bands | Some computer mouse pads |
| Balloons | Panty hose or elastic in underwear |
| Rubber goggles | Rubber electrical cords on appliances |
| Rubber innersoles | Rubber boots or rain coats |
| Some medical products such as airway masks, catheters and dressings | Items with rubber handles such as tooth brushes, golf clubs, tennis racquets |
Risk factors for latex allergy
Factors that may increase a person’s potential for developing latex allergy include:
- A history of asthma, eczema or hay fever (called atopy)
- Damaged skin i.e. dry and cracked skin when wearing latex gloves
- Working in the healthcare industry and frequent wearing of latex gloves
- Use of powdered latex gloves. Powder facilitates the transfer of the latex allergen to the skin.
- Long term exposure to latex, especially individuals who have undergone multiple surgical operations.
Management of latex allergy:
Unfortunately there is no cure for latex allergy, so it is important to avoid contact with latex products at work and home. People who have been diagnosed with latex allergy should avoid contact with all latex products including latex gloves, balloons and condoms.
It is also important that those people inform their general practitioner, dentist and other healthcare providers about their allergy.
Patients should be encouraged to contact manufacturers if they are uncertain if products contain latex or not.
People with latex allergy may need to wear a Medic Alert bracelet, as many healthcare facilities use latex products, which is particularly important in an emergency medical situation.
In rare cases, people may have a severe reaction to latex, called anaphylaxis. Anaphylaxis causes swelling, difficulty breathing, collapse and occasionally even death. An ‘EpiPen®’ which is a special injectable adrenaline syringe, is used in an emergency to treat anaphylaxis.
For more information on anaphylaxis visit the Australasian Society of Clinical Immunology and Allergy website www.allergy.org.au
| Special note: Remember – HCWs allergic to latex need to find an alternative suitable glove. These may include gloves made from nitrile and neoprene. Vinyl gloves are not suitable as they do not adequately protect against bodily fluids. Other Immediate reactions Generally the most relevant immediate reactions for the skin are house dust mite and malassezia furfur. These can aggravate underlying atopic eczema and/or contribute to seborrheic eczema. These are often worth checking for atopic patients as house dust mite avoidance is associated with improvement and malassezia ? are also treated. Occassionally people will develop relevant immediate reactions to animals so these are worth checking. Reactions to pollens, moulds, grasses and trees are rarely relevant to the skin. |
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