Best Syringes for Subcutaneous Peptide Injections

For most peptide injections under the skin, use a U-100 insulin syringe in the smallest barrel that holds your dose, with a short, fine needle. A 0.3 mL syringe holds 30 units and is the easiest to read for small doses. Check that "U-100" is printed on the box before your first draw. If you draw your dose on a U-40 syringe by mistake, you get 2.5 times the amount.

Which syringe size do I need for peptide injections?

Peptide doses are usually drawn with U-100 insulin syringes. On these, 100 units equal 1 mL, so each unit is 0.01 mL (U-100 units-to-mL chart).

U-100 syringes come in three common barrel sizes (syringe conversion chart):

One unit is 0.01 mL on all three. Markings vary by manufacturer, so look at the barrel before you draw.

Pick the smallest barrel that holds your dose. A small dose is much easier to read on a 0.3 mL barrel than squeezed into the first few lines of a 1 mL barrel (U-100 units-to-mL chart).

You may also see tuberculin syringes. They are marked in mL, not units (syringe conversion chart). Use one only if your instructions are written in mL.

What needle length and gauge hurt the least?

Shorter needles tend to hurt less. In insulin studies, people compared needles on a 150 mm pain scale. They rated 4 mm needles 11.9 mm lower than 5 mm needles and 23.3 mm lower than 8 mm needles. About the same amount of liquid leaked back out of the skin with the shorter needles (insulin needle length review).

Insulin syringes come with needles of different lengths. BD Ultra-Fine syringes, for example, come with 6 mm, 8 mm or 12.7 mm needles. The authors of the insulin review argued that the long 12.7 mm needle should be retired, because shorter needles hurt less and worked as well for insulin (insulin needle length review).

Gauge is the needle's thickness. A higher number means a thinner needle. In one small trial of blood-thinner shots, a thinner needle was not clearly better. Researchers compared a 30-gauge, 5/16-inch insulin syringe with a 26-gauge, 3/8-inch tuberculin syringe. They found no significant difference in bruise size (4.2 vs 3.8 cm) or pain (0.3 vs 0.5 out of 10) (enoxaparin needle trial). The authors said a larger study is needed to know whether needle size changes how often bruises form, so this one small trial does not settle it.

The needle is only part of the sting. How much liquid you inject, how fast you push, where and how you inject, and the formula itself (its acidity and preservatives) all affect how much a shot hurts (review of injection-site pain). If a shot burns, tell your clinical team.

How many units is my peptide dose?

Units on the barrel measure liquid, not peptide. How much peptide sits in each unit depends on how the vial was mixed. A 5 mg vial mixed with 2 mL of water carries 25 mcg per unit, so 10 units is 250 mcg. Mix the same vial with 1 mL of water and each unit carries 50 mcg, so 10 units is 500 mcg (U-100 units-to-mL chart). That is the same 10 units on the barrel and twice the peptide.

You can see this on Reddit. One new BPC-157 user wrote: "ive been taking 5 units for 4 days now and plan to up the dosage to 10 units starting next week." Without the vial size and the mixing amount, nobody can tell how much peptide that is.

Ask your clinical team to write your dose two ways: the amount in mcg or mg, and the number of units for your vial and mixing. Then check that the units fit the barrel you bought. A 25-unit dose fits a 0.3 mL syringe. A 40-unit dose needs at least a 0.5 mL syringe.

What syringe mistakes can change my dose?

• Using a U-40 syringe by mistake. U-40 syringes are made for pet insulin but still turn up in orders. If you draw a U-100 dose on a U-40 syringe, you get 2.5 times the amount (U-100 units-to-mL chart). Check the barrel print before your first draw.
• Assuming every line is one unit. On many 1 mL syringes, each small line is 2 units, or 0.02 mL (syringe conversion chart).
• Slipping a decimal. 5 units is 0.05 mL, not 0.5 mL. If a number looks ten times too big or too small, check it again.
• Reading from the wrong edge of the plunger. Check the syringe instructions to see which edge of the plunger lines up with the scale.
• Reusing syringes. Insulin syringes like TRUEplus are sold as single-use, and each one comes sealed and sterile.

Where can I buy insulin syringes and how much do they cost?

They are cheap. Costco lists a 100-count box of TRUEplus Single-Use U-100 Insulin Syringes for $11.59 at the member price. These are 0.3 mL syringes with a 31-gauge, 5/16-inch (8 mm) needle, so each shot costs about 12 cents.

Stock varies by store. When that price was recorded, the box was in stock at 135 of 290 reporting Costco warehouses. Check your local store before you go.

Buy the barrel size that fits your dose, not the biggest box on the shelf. The right syringe depends on your dose, and your dose depends on your treatment and your vial. Take the quiz to start a plan with our clinical team. They can give you your dose in units and tell you which syringe size fits it.