How do I know if my cartridge needs replacing?

Cartridges can last up to 1 month with proper care, but for safety we recommend using each one a maximum of 3 times, always sanitizing thoroughly after every session (soak in 70% isopropyl alcohol for 10 minutes, then air-dry needles-up). Replace sooner if the needles feel dull, scratchy, bent, or if results seem less consistent. Never reuse a cartridge that’s damaged or can’t be fully sanitized.