What to look for: three specs
- Volume: 1 mL. The barrel holds 1 mL across 100 unit marks. Each unit = 0.01 mL. This is what reconstitution calculator "units" output assumes.
- Scale: U100. 100 units per mL. NOT U40 (veterinary).
- Needle gauge: 29G or 31G. 31G is finer, 29G is slightly stiffer. Both work for subcutaneous injections. Length 5/16" (8 mm) or 1/2" (13 mm).
Where to buy (Prime-eligible)
1 mL U100 syringes (31G, 5/16")
Most common spec. Fine 31G needle is barely felt. Buy a 100-pack — you use one per injection.
BD UltraFine (gold-standard brand)
Becton Dickinson is the household name. Slightly more expensive than generic but with the most consistent QC and sharpest needles.
EasyTouch / Exel (budget)
Reliable budget brands. Same U100 scale, same needle gauges. Most home users find these work as well as BD.
3 mL Luer-lock (for drawing BAC only)
Optional. Lets you transfer the whole BAC volume in one pull. Don't use for injection — unit scale isn't fine enough.
Common mistakes
- Buying U40 instead of U100. Veterinary scale, math will be wrong by 2.5×. Always U100.
- Buying 0.5 mL or 0.3 mL barrels. Smaller scales (50 or 30 unit marks). Fine if your dose is always ≤30 units, but 1 mL is more flexible.
- Reusing syringes. Single-use only. Reuse blunts the needle and adds contamination risk.
- Using 1.5" or 1" needles. Those are intramuscular. Subcutaneous wants 5/16" or 1/2".
How many do I need?
For weekly GLP-1 injections, a 100-pack lasts about 2 years. For daily protocols (BPC-157, etc.), ~3 months. Buy in 100-packs — per-unit cost drops sharply.
Don't forget the sharps container. Used syringes go in an FDA-cleared puncture-proof container, never household trash. See our supplies checklist for the full list.