Tattoos may become itchy for several reasons from completely harmless reasons to potentially dangerous ones. The first thing to do is make an appointment with a doctor to ensure that there is not an allergic reaction occurring. While an allergic reaction, most likely to the ink, is rarely the cause of an itchy tattoo, it is important for people to clear this as a possible cause.
A more likely culprit that causes itchy tattoos is the weather. Just as the skin reacts to warmer or colder climates, so does the tattoo. Warmer weather may cause the skin to stretch and itch, while others may notice that colder temperatures dry out the skin resulting in itch.