The post or hook touches your skin all day — and so does the back (the clutch). A pair can have a safe titanium post and a mystery-metal back, and your ears will only ever meet the back. People with nickel sensitivity report reacting to pairs labeled “hypoallergenic” — the clutch is often the part nobody checked.

1. The back is the same safe metal as the post. A safe post does not help if the clutch is a different, unnamed metal.
2. The listing names the back metal at all. Most listings do not — if it is not stated, ask.
3. If the back metal is unknown, ask the seller — or swap the backs for ones in the same safe metal as the post.

1. What exact metal and grade is the post or hook — for example, “ASTM F136 titanium” or “316L”?
2. What metal is the back (clutch)? Is it the same metal as the post?
3. Is there nickel anywhere — in the post, the back, or under any plating?
4. Is it plated or filled — and what is the metal underneath?
5. For silver or gold, what is the alloy — what else is mixed in besides silver or gold?
6. Can you put the metal in writing on the listing?

If the seller cannot answer, that is your answer.

“Hypoallergenic” is not a regulated word in jewellery — any seller can print it. “Nickel-free” is the more useful claim. A concrete benchmark: under the EU’s REACH rules, a post assembly worn in a pierced ear may release no more than 0.2 micrograms of nickel per square centimetre per week. Nickel is the most common cause of metal contact allergy — the American Academy of Dermatology estimates it affects more than 18% of people in North America.