Author: Vanessa Ngan, Staff Writer, 2012.
Jewellery allergy is a common cause of contact allergic dermatitis. Most jewellery allergy is caused by the metal nickel (see nickel allergy) which is used in the manufacture of precious metal alloys. In less expensive jewellery, nickel is often used in the base metal which is then plated with gold or silver. Many people who believe that they are allergic to gold or silver jewellery are allergic to nickel, which can occur as a trace element in gold or silver or has been used in the manufacture of gold jewellery to whiten and strengthen the piece.
In affected individuals, dermatitis develops in places where nickel-containing metal is touching the skin. The most common sites of jewellery allergy are the earlobes (from earrings), the fingers (from rings), and around the neck (from necklaces); the affected areas become intensely itchy and may become red and blistered (acute dermatitis) or dry, thickened and pigmented (chronic dermatitis). Sometimes dermatitis later affects areas that are not in contact with jewellery, particularly the hands. Pompholyx is a blistering type of hand dermatitis that is prevalent in people with a previous history of jewellery allergy and may be due to contact with other sources of nickel such as coins and keys.
Jewellery reactions are not always due to an allergy to a specific metal. Consider other reasons for a rash on the site of a particular item of jewellery.
By looking at a piece of jewellery, it is very difficult to determine whether or not it contains nickel. One should assume that all metal jewellery has some amount of nickel in it unless it made of stainless (surgical) steel, is either 18- or 24-carat gold, is sterling silver, or pure platinum.
Gold for jewellery is typically measured in karats (also spelt carats).
To make up the rest of the metal, gold is alloyed with other metals. For people with metal allergy, particularly nickel allergy, the question is which metals are your gold jewellery alloyed with? Gold can be alloyed with many different types of metals which alter its hardness, colour and other properties. For example, yellow gold may be alloyed with silver and copper, while white gold is usually alloyed with nickel. Rhodium, a silvery-white metal related to platinum, is often used to plate yellow gold to make it into white gold. And even white gold with nickel is often rhodium-plated to make it appear whiter and shinier. Although the initial plating will protect you against any nickel in the gold, it eventually wears off over months or years. This leaves the white gold (alloyed with nickel) in contact with your skin.
There are three grades of silver for jewellery — pure silver, sterling silver and silver-plated. Pure silver is 99.9% silver but can be too soft and malleable to handle when making into jewellery. Sterling silver is 92.5% pure silver alloyed with copper. In some cases of sterling silver, a small percentage of other metals may be in the mix so traces of nickel may be present. Silver-plated jewellery is a base metal (and may contain nickel) that has been plated with a fine layer of silver alloy.
Allergic contact dermatitis to metal jewellery may develop at any age. In most cases, this is due to nickel allergy, and once it has occurred, it persists for many years, often life-long. Some people develop dermatitis (also called eczema) from even brief contact with nickel-containing items, while others after many years of wearing them without problems suddenly break out in a rash. This is usually confined to skin sites in contact with the metal but can spread more widely in severe cases.
Nickel allergy is more common in women, probably because they are more likely to wear jewellery than men, although this is changing. While nickel allergy is the most common jewellery allergy to occur, allergy to other metals used in jewellery is possible. However, it appears to be rare.
Treatment requires removing responsible jewellery.
If you have a jewellery allergy, a dermatologist can perform a skin patch test to determine if you have a nickel allergy. Once your nickel allergy is confirmed, it is essential to avoid contact with nickel-containing metals. The following tips may help when purchasing jewellery.
Test your metal items to see if they contain nickel. Obtain a nickel-testing kit from your dermatologist, pharmacist, or online. The kit consists of one or two small bottles of clear fluid (dimethylglyoxime and ammonium hydroxide). When mixed in the presence of nickel, a pink colour results.
Apply a drop of the fluid on to the metal item to be tested — first, try it on a 10-cent coin. Use a cotton bud to rub gently – observe the colour on the bud. If it remains clear, the item has no free nickel and will not cause dermatitis. If it is pink, it contains nickel and may cause problems if the item touches your skin. These chemicals will not harm your jewellery.
Your dermatologist may have further specific advice, particularly if you are highly sensitive to nickel or other metals.
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