Author: Hon A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2003.
Over 90% of natural rubber comes from the latex, or milky sap, of the rubber tree - Hevea brasiliensis. Latex is used in a large number of products including adhesives, foam, carpet backing and in a number of "dipped" products. Dipped products include surgical gloves, household gloves, catheters, condoms, balloons, etc. Natural latex rubber is also found in toys, erasers, sports equipment, clothing, elastic bands, and many medical and dental devices.
For reasons not yet clearly understood, some individuals can become allergic to certain constituents of the latex molecule. Once allergic, you may remain sensitive for the rest of your life.
Growth in the latex allergy problem has been related to the rising demand and use for latex products. The onset of recommendations for universal precautions resulted in increased use of latex gloves - to meet the increased demand, manufacturing processes may have changed resulting in a more highly allergic product.
Anyone who is exposed to latex may become sensitised - fortunately, the majority of individuals do not. However, certain populations are more at risk:
Contact urticaria usually presents with itching and swelling of the skin at the site of contact with latex. This may, for example, be hands from wearing gloves, genitals from contact with condoms, etc. The symptoms usually start within 5 - 15 minutes after coming into contact with the latex article, although it can be delayed for several hours. Symptoms can continue for a variable period, from several hours to days after the latex contact has ceased.
Contact dermatitis from latex may take several days to appear. It presents with an itchy, scaly rash, although there may be small blisters if the reaction is acute. The rash will usually last several days to weeks but if exposure to latex continues, the rash will last longer. Contact dermatitis is not generally caused by sensitivity to latex protein but rather to the chemicals used in the manufacture of the latex product, including antioxidants and rubber accelerators e.g. thiuram, carbamates, MBT, etc.
Immediate-type hypersensitivity requires previous sensitisation and is the most potentially dangerous reaction to latex. Clinical presentations vary but may include contact urticaria, coryza, conjunctivitis, stinging or burning, asthma, and, with mucosal or parenteral exposure, anaphylaxis. A common cause for the asthmatic reaction is powdered gloves. The starch powder picks up the latex proteins and when the gloves are removed the powders can then be inhaled or come into contact with the skin on the face where it can cause an allergic reaction.
Contact through skin, mucous membranes, parenteral, intravenous and inhalation.
In most cases, a diagnosis of latex allergy can be made from an accurate history and clinical examination. There are a number of skin tests which can confirm latex sensitivity, including patch tests (for allergic contact dermatitis type reactions), skin prick test (for contact urticaria type reactions) and radioallergosorbent assay blood test (RAST) which is not as accurate as the skin tests.
Help prevent latex sensitivity
The following guidelines are summarised FDA advice to health professionals to ensure a patient's latex allergy is not overlooked:
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