Higher gauge (thinner) needles reduce pain, but they may take longer to inject oil-based testosterone. Although oil is thick, a 25 gauge needle is commonly used for injections. Using too short a needle for intramuscular injections can leave testosterone in the fatty layer, leading to irritation and poor absorption. While preferences vary, most men find a 23–25 gauge, 1-inch needle works well for intramuscular injections in the thigh or deltoid. For thigh injections, a shorter 23G, 1 in needle is often sufficient. Should your lab tests reveal that you have low testosterone, you will be prescribed the necessary dosage and regimen of testosterone injections that best meet your budget, symptoms, and lifestyle. The 27G needle is ideal for those who prioritise gentleness and want the injection to feel as subtle as possible. With time, many people develop a deep trust in the 25G gauge because it feels kind and approachable. A Gentle Look at 25G Needles for TRTThe 25G needle is finer than both the 21G and 23G, offering a noticeably softer sensation during injection. Over time, this familiarity helps create confidence and calmness during routine injections. Their strength can feel reassuring, especially during intramuscular injections where depth and steadiness matter. Listening to how the body responds during and after injections helps guide the choice. The slow and steady pace they encourage supports emotional grounding, making the injection feel nurturing rather than intimidating. Why Others Prefer Finer GaugesOther individuals prefer finer gauges such as 25G and 27G because they offer a softer and more delicate sensation. Emotional comfort shapes every part of the experience, from preparing the syringe to completing the injection. A thicker needle supports faster flow, while a finer one brings a slower and more delicate pace. Comparing Comfort Across All Four GaugesComfort plays a large role in choosing a needle for TRT, and comparing the four gauges reveals unique qualities in each. People who feel anxious about injection depth often appreciate the delicate nature of this gauge, finding reassurance in its fine structure. The 23G offers slightly slower flow but remains easy and comfortable to manage. Comparing Flow Between 21G, 23G, 25G and 27G NeedlesFlow is another key difference between the gauges. It allows individuals to select the gauge that aligns with their personal preference and supports their wellbeing. For instance, a 25 gauge needle is thinner than a 22 gauge needle. Over time, these associations help individuals settle comfortably into their choice with a sense of trust and ease. This familiarity becomes empowering and helps individuals refine their preference with ease. However, recent studies like this JCEM trial support subcutaneous injections as an effective alternative. Has anyone been able to find the happy medium of being able to draw and inject with the same needle? Never throw used needles into household trash or recycling. If the medication comes in a vial (e.g. estrogen injection, Nebido), use a blunt needle instead. The gauge refers to thickness — the lower the number, the thicker the needle. In the US, needles are identified by gauge (G) and length (inches or millimeters). Below, you’ll find everything you need to know about needles, how to inject safely, and how to dispose of them properly. Testosterone replacement therapy (TRT) involves injecting testosterone into the body to raise low testosterone levels. Comparing 21G, 23G, 25G and 27G needles for TRT helps bring clarity to one of the most common questions people have when starting testosterone therapy. Men following a microdosing TRT protocol (smaller, more frequent injections) often prefer very fine needles (27–30 gauge, ½ inch). Because testosterone is an oil-based medication, choosing the right balance between gauge (thickness) and length is critical for smooth injections. I'm starting my trt and wondered what gauge and length pins you guys have found suits you best for IM injections. 21G and 23G needles are the most common for intramuscular injections in the US. Most people use a 21G, 1.5 inch needle for glute injections and a 23G, 1 inch needle for thigh injections.