Allergic contact dermatitis often occurs as a result of jewellery allergy. 

The main culprits behind jewellery allergy are the two metals, nickel and cobalt, which are frequently used in the production of precious metal alloys. In lower-cost jewellery, nickel is often present in the base metal and then coated with gold or silver. Many individuals who believe they are allergic to gold or silver jewellery are actually allergic to nickel because it can be found as a trace element in gold or silver, or it may have been used in the manufacturing process of gold jewellery pieces to enhance their whiteness and strength.

When the skin comes into contact with nickel-containing metal, jewellery allergy presents as dermatitis. The most commonly affected areas are the earlobes (from earrings), the fingers (from rings), and the neck (from necklaces). The affected areas become intensely itchy and may exhibit redness and blistering (acute dermatitis), or they can become dry, thickened, and discolored (chronic dermatitis). Occasionally, dermatitis may also develop in areas that do not have contact with jewellery, such as the hands. Pompholyx, a blistering form of hand dermatitis, is often observed in individuals with a history of jewellery allergy and may be caused by contact with other sources of nickel, such as coins and keys.

Jewellery reactions can occur for reasons other than an allergy to a specific metal. Some other factors that can cause a rash at the site of a particular piece of jewellery include irritant contact dermatitis, psoriasis, vitiligo, and infections.

Irritant contact dermatitis can be triggered by friction, particles, and dirt on the metal’s surface, soap and water trapped beneath the item, or other non-metal components of the jewellery. Irritant reactions are more common in individuals with sensitive skin or atopic dermatitis.

Conditions like psoriasis and vitiligo can koebnerise and spread to an area of injury, such as the site where a tight watch strap, necklace, or bangle is worn.

Infections, such as Staphylococcus aureus, can occur at a piercing site, resulting in oozing and crusting (impetigo or wound infection).

Determining the presence of nickel in jewellery solely by appearance is quite challenging. It is generally safer to assume that most metal jewellery contains some nickel unless it meets specific criteria such as stainless (surgical) steel, 18- or 24-carat gold, sterling silver, or pure platinum.

Gold used in jewellery is commonly measured in karats (also spelt carats).  The key compositions are the following: 24-karat gold is pure gold, with 99.9% gold content and 0.1% other metals; 18-karat gold consists of 75% gold; 12-karat gold contains 50% gold; and Nine karat gold comprises 37.5% gold.

To give gold the desired characteristics, it is alloyed with other metals. For individuals with metal allergies, especially nickel allergies, it is important to know which metals are present in the gold alloy of their jewellery. Gold can be alloyed with various metals that affect its hardness, color, and other properties. For instance, yellow gold may be alloyed with silver and copper, while white gold commonly contains nickel. Rhodium, a silvery-white metal similar to platinum, is frequently used to plate yellow gold and give it a white appearance. Even white gold alloyed with nickel is often rhodium-plated to enhance its whiteness and shine. Although the initial plating provides protection against any nickel in the gold, it eventually wears off over time, exposing the white gold (alloyed with nickel) to direct contact with the skin.

In terms of silver, there are three grades of silver used in jewellery: pure silver, sterling silver, and silver-plated items. Pure silver consists of 99.9% silver, but it can be too soft and malleable for practical use in jewellery making. Sterling silver is an alloy containing 92.5% pure silver mixed with copper. In some cases of sterling silver, small amounts of other metals may be present, potentially including traces of nickel. Silver-plated jewellery involves a base metal (which may contain nickel) coated with a thin layer of silver alloy.

Allergic contact dermatitis caused by metal jewellery can develop at any age and tends to persist for many years or even a lifetime. Nickel or cobalt allergy is the most common cause, although other metal allergies are rare. Some individuals may experience dermatitis (eczema) even with brief contact with nickel-containing items, while others may develop a rash after years of wearing them without any issues. Typically, the reaction is localized to the areas of skin in direct contact with the metal, but in severe cases, it can spread more extensively.

Nickel allergy is more prevalent among women, likely because they tend to wear jewellery more frequently, although this trend is changing. When it comes to treating jewellery allergy, the primary approach involves avoiding the responsible jewellery that triggers the allergic reaction.

Jewellery allergy is diagnosed by clinical history and the particular skin-allergy test, patch testing. 

To prevent jewellery allergy, individuals with a known allergy can undergo a skin patch test conducted by a dermatologist to confirm the presence of a metal allergy, particularly nickel or cobalt. Once the allergic reaction is confirmed, it is crucial to avoid any contact with that specific metal.

One of the treatment recommendations is to explore alternative white gold alloys that are based on palladium, silver, or other white metals. Palladium alloys tend to be more expensive than nickel-based ones. Higher-karat white gold alloys offer better corrosion resistance compared to pure silver or sterling silver.

If a patient plans to get ears or other body parts pierced, they should ensure it is done with a stainless steel needle, and opt for jewellery made of stainless steel, 18- or 24-karat gold.

They should also look for hypoallergenic jewellery options, such as those made of stainless steel, at least 18-karat gold, sterling silver, or polycarbonate plastic.

If a patient needs to wear earrings that contain nickel, they should consider adding plastic covers designed explicitly for earring studs.

If a piece of jewellery that someone wears regularly, such as a wedding ring, triggers a reaction, an individual should consult with a jeweller about the possibility of plating it with a non-allergenic metal like rhodium or platinum. It should be kept in mind that the coating will eventually wear off and would require re-plating in the future.

Centre for Medical and Surgical Dermatology offers unique and personalized treatment options for allergic contact dermatitis to jewellery for each patient.