How do I read a syringe?
The hash marks on the tube of the syringe indicate a certain number of milliliters or fractions of a milliliter. Most syringes include incremental hash marks between larger, numbered ones. The volumes discussed here are in milliliters (mL) which may be used interchangeably with the term “cc.”
- On a 1 mL syringe, each of the smallest lines count for 0.02 mL, and the longer lines indicate 0.1 mL intervals.
- On a 3 mL syringe, the smallest lines count for 0.1 mL intervals, the longer lines indicate 0.5 mL intervals.
Do I need to draw up “extra” (beyond the prescribed volume) to account for medication “lost” or left in the needle and tip of the syringe?
No. The volume of medication prescribed accounts for “loss” in the syringe tip and needle. You should draw your medication up so that the plunger is at the correct dose line as shown above, and then switch the needle on your syringe from your “draw” needle (usually 18–20 gauge) to your “injection” needle (usually 22–25 gauge) and proceed directly with your injection as shown in these videos.
How long can I use one vial of medication?
Injectable medication vials are packaged and labeled for single-use or multiuse. Most commonly, testosterone is available as a single-use 1 mL vial and delestrogen is available as a 10 mL multiuse vial. This labeling has to do with the preservatives, packaging, and testing a particular medication and vial has gone through.
Most patients using single-use testosterone vials will be instructed to inject a small amount of the volume in the vial (example 0.4 mL of a 1 mL vial); the remainder of the medication in the single-use vial should be discarded. Said another way, a person prescribed a 0.4 mL dose of testosterone each week, who is provided 1 mL single-use vials by the pharmacy, will need a new 1 mL vial each week (discarding the extra medication each week). We recognize that some people use single-use vials for several doses but cannot recommend this given the package labeling.
Multiuse vials are most common for delestrogen but are occasionally available for testosterone. Multiuse vials are intended for use for 28 days after the vial is punctured (the first dose is removed). For people doing weekly injections, this means a multiuse vial can be used for 4 injections over the course of 4 weeks. In the setting of a 5 mL vial of delestrogen, this typically means there will be a large volume of remaining medication after 28 days that should be discarded. We recognize that some people use multiuse vials for more than 28 days after puncturing but cannot recommend this given the package labeling.
