What is a 23-gauge needle use for?

18 gauge needles can be used for any piercing as long as you ask for it. Most standard piercings are pierced at either 14 or 16 gauge. Personally, I asked for my septum to be pierced at an 18 gauge so the jewelry wasn't as bulky and was easier to hide. Just keep in mind that if you get anything pierced with an 18 gauge needle, you need 18 gauge jewelry. Trying to shove standard size jewelry into it (especially if it isn't fully healed) could cause irritation, infection, or rejection.