If you’re using testosterone injections, one of the most common questions I hear is: “Do I need to change needles between drawing and injecting?” Hi — I’m Dr. Tony, cosmetic and gender surgeon in Seattle, and here’s the quick explanation. Testosterone isn’t just liquid medication. It’s suspended in a carrier oil, and some of these oils—especially in long-acting testosterone formulations—are very thick. Because of that viscosity, many people use a larger needle (like an 18-gauge) to draw the medi