Body Jewelry should be hypoallergenic. A number of materials are used, with varying strengths and weaknesses. Surgical stainless steel, niobium and titanium are commonly used metals, with titanium the least likely to cause allergic reaction of the three. Platinum and palladium are also safe alternatives, even in fresh piercings. Initial piercings should never be done with gold of any grade, as gold is mixed with other metals, and sterling silver is not a good alternative in a body piercing, as it may cause allergies in initial piercings and will tarnish in piercings of any age. An additional risk for allergic reaction may arise when the stud or clasp of jewelry is made from a different metal than the primary piece.

Body Jewelry is measured by thickness and diameter/length. Most countries use millimeters. In the USA, the Brown & Sharpe AWG gauging system is used, which assigns lower numbers to thicker middles. 00 gauge is 9.246 millimetres (0.364 in), while 20 gauge is 0.813 millimetres (0.032 in).