What should you know about metal allergy testing?

A clinician places small amounts of suspected metals on the back under adhesive patches. The patches stay in place for a period, then the skin is checked again because contact reactions can develop later rather than immediately. Testing commonly considers nickel, cobalt or chromate according to your history and the products you contact. A positive result shows skin sensitivity to that test substance; it does not prove that every rash is caused by metal or predict reactions in every body area. Tell the clinician about rashes from jewellery, watches, belt buckles, cosmetics, dental materials or workplace exposure. Metal allergy is different from food allergy and from breathing-related conditions such as [Asthma](/conditions/asthma/).

Keep a record of when the rash starts, where it appears and which items touch the skin. Ask the testing clinic which creams or medicines to pause, because some products can reduce a skin reaction and should only be changed with professional guidance. Do not apply suspected metals to irritated skin as a home test. During testing, keep the patches dry and avoid strenuous activity that may loosen them. If a metal is identified, ask about safer alternatives and how to check product labels. A clinician can also consider eczema, irritant dermatitis or another cause if the result is negative.

Contact a clinician if a rash spreads, becomes painful, develops blisters, or does not improve after the suspected item is removed. Seek emergency help for swelling of the lips, tongue or throat, trouble breathing, faintness or widespread rapidly developing hives; these symptoms may indicate [Anaphylaxis](/conditions/anaphylaxis/). A typical contact reaction is mainly at the area of exposure, while breathing symptoms require urgent evaluation rather than routine patch testing.

Ask: Which metals should be included? Do my medicines or skin creams affect testing? How will the result change what I use at home or work? Could another skin condition explain the rash?