Testosterone Cypionate 100 mg/mL Dosing Protocol
What the label says, how many units to draw on a U-100 syringe, and how long a vial lasts.
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- Alpha Health Finder Editorial Team
- Last reviewed
Prescription medication, educational reference only. This page converts a dose your prescriber has already set into the volume and syringe units you draw. It does not tell you what dose to take. Testosterone Cypionate requires a diagnosis and clinical supervision.
Quickstart
- At 100 mg/mL, 1 unit on a U-100 insulin syringe = 1 mg. This is the conversion most people get wrong.
- The FDA label for Depo-Testosterone states For replacement in the hypogonadal male, 50 to 400 mg every two to four weeks.
- The label specifies intramuscular, deep in the gluteal muscle.
- A 10 mL vial holds 1000 mg.
- This is the lower of the two labelled strengths — Depo-Testosterone is supplied at 100 mg/mL and 200 mg/mL. The same prescribed dose needs twice the volume here.
- Store at 20–25 °C (68–77 °F). Do not refrigerate.
Dose calculator
Pre-filled for Testosterone Cypionate 100 mg/mL. Change the concentration if your vial differs.
This barrel is numbered in millilitres, not the other. Intramuscular route, 18–21G to draw, 22–25G to inject, 1–1.5 in (25–38 mm) for intramuscular.
This barrel is read in millilitres — it carries no unit marks. This converts a dose your prescriber has set — it does not choose one.
Volume and syringe units by dose
1 unit = 1 mg
Arithmetic only, at 100 mg/mL. Which dose applies to you is your prescriber’s decision — this table converts a prescribed milligram figure into what you draw.
| Dose | Volume | U-100 units | Frequency |
|---|---|---|---|
| 25 mg | 0.25 mL | 25 | As prescribed |
| 50 mg | 0.5 mL | 50 | As prescribed |
| 60 mg | 0.6 mL | 60 | As prescribed |
| 75 mg | 0.75 mL | 75 | As prescribed |
| 80 mg | 0.8 mL | 80 | As prescribed |
| 100 mg | 1 mL | 100 | As prescribed |
| 150 mg | 1.5 mL | 150 | As prescribed |
| 200 mg | 2 mL | 200 | As prescribed |
How long a vial lasts
10 mL vial · 1000 mg
- 100 mg/week → 10 weeks
- 150 mg/week → 6 weeks
- 200 mg/week → 5 weeks
Volume is not the only limit — your pharmacy sets a beyond-use date once a multi-dose vial is entered, which can arrive before the vial empties.
Which syringe, and why
Testosterone cypionate is suspended in cottonseed oil — 736 mg of it per millilitre, per the label — with benzyl benzoate and benzyl alcohol. That oil is viscous, and the label specifies deep intramuscular injection into the gluteal muscle. Both facts point at a luer-lock barrel with a detachable needle: you draw through a wide gauge (18–21G), swap to a finer one to inject (22–25G), and you need 1 to 1.5 inches of needle to reach muscle. A fixed 29–31G insulin needle is both too fine to draw cold oil through at any speed and, at half an inch, too short for a gluteal intramuscular injection in most adults.
| Barrel | Numbered in | Needle | Reached for when |
|---|---|---|---|
| 30-unit insulin (0.3 mL) | units | 29–31G5/16–1/2 in (8–13 mm) · fixed | Small aqueous volumes where every unit matters. The finest resolution of the three insulin barrels. |
| 50-unit insulin (0.5 mL) | units | 29–31G5/16–1/2 in (8–13 mm) · fixed | Mid-range aqueous doses that would crowd a 30-unit barrel. |
| 100-unit insulin (1 mL) | units | 29–31G5/16–1/2 in (8–13 mm) · fixed | Doses near a full millilitre. Marks are 2 units apart, so it reads coarser than the smaller barrels. |
| 1 mL luer-lockthis protocol | mL | 18–21G to draw, 22–25G to inject1–1.5 in (25–38 mm) for intramuscular · detachable | Oil-based solutions and intramuscular injection, where a detachable needle lets you draw through a wide gauge and inject through a finer one. |
| 3 mL luer-lock | mL | 18–21G to draw, 22–25G to inject1–1.5 in (25–38 mm) for intramuscular · detachable | Larger intramuscular volumes, or when drawing from several vials. |
“Draw 0.5” means two different things. On a luer-lock barrel that is 0.5 mL. On an insulin barrel the numbers are units, and 0.5 units is one hundredth of the same volume. Read which unit your barrel is printed in before you draw, and confirm the figure your prescriber gave you refers to the same one.
Step by step
- 1
Confirm the diagnosis first
The label requires serum testosterone measured on at least two separate mornings, both below the normal range, before therapy is initiated.
- 2
Inspect the vial
Testosterone cypionate is a clear, pale-yellow oil solution. Check the expiry date and that the solution is free of particles. Crystals can form if the vial has been cold; warming to room temperature in the hand redissolves them.
- 3
Clean the stopper
Wipe the rubber stopper with an alcohol swab and let it dry.
- 4
Draw the prescribed volume
Use the table on this page to convert your prescribed dose in milligrams to syringe units. Oil solutions draw slowly — a wider-gauge needle for drawing and a finer one for injecting is common practice.
- 5
Expel air
Hold the syringe needle-up, tap to raise bubbles, and push the plunger until a drop appears at the tip.
- 6
Inject as directed
The label specifies deep intramuscular injection into the gluteal muscle, and states the product must not be given intravenously. Your prescriber will confirm site and technique.
- 7
Rotate sites and record the dose
Alternate injection sites between doses and log the date and amount. A written record is what makes a trough lab result interpretable.
Storage
- Store at 20–25 °C (68–77 °F), the USP controlled room temperature range on the label.
- Keep the vial in its carton, away from light.
- Do not refrigerate — cold causes the oil to thicken and crystals to form.
- A multi-dose vial should be discarded per your pharmacy’s beyond-use date once entered.
Supplies
For a 12-week plan at 100 mg/week.
- 210 mL vials at 100 mg/mL (1,000 mg each — 10 weeks per vial at 100 mg/week)
- 123 mL syringes with drawing and injecting needles
- 24Alcohol prep pads
- 1Sharps disposal container
- 2Lab draws — baseline and a follow-up at your prescriber’s interval
What to monitor
| Marker | When | Why |
|---|---|---|
| Total testosterone | Baseline, then as directed — commonly at a trough, immediately before the next dose | Confirms the dose is achieving the intended range. The label requires two low morning values before therapy begins. |
| Haematocrit | Baseline and periodically | Erythrocytosis is the most common clinically significant adverse effect of testosterone therapy and may require dose reduction or phlebotomy. |
| PSA | Baseline and periodically in men over 40 | The Endocrine Society guideline recommends prostate monitoring in men starting testosterone who are at higher baseline risk. |
| Estradiol | If symptoms suggest | Testosterone aromatises to estradiol. Testing is symptom-driven rather than routine in most practices. |
Clinics prescribing TRT
- TRT NationTampa, FL4.9(1698)
- BioDesign Men's Clinic of TampaTampa, FL5.0(1029)
- Chicagoland Men's Health - Low Testosterone Replacement TherapyChicago, IL5.0(488)
- Overtime Men’s HealthTampa, FL4.9(444)
- The Health Carpenter Direct Primary Care & AestheticsOrlando, FL5.0(427)
- Vitality Health SFLBonita Springs, FL5.0(390)
Frequently asked questions
- How many units is 80 mg of testosterone cypionate at 100 mg/mL?
- 80 units on a U-100 insulin syringe. At 100 mg/mL, each mL contains 100 mg and a U-100 syringe is graduated so 100 units equals 1 mL — therefore 1 unit is 1 mg, and 80 mg is 80 units (0.8 mL).
- Is 100 mg/mL different from 200 mg/mL in any way other than volume?
- No — it is the same drug in the same cottonseed-oil vehicle, and the label covers both strengths under one dose range. The difference is entirely mechanical: a 100 mg dose is 1 mL at 100 mg/mL and 0.5 mL at 200 mg/mL. At 100 mg/mL a 200 mg dose is a full 2 mL, which will not fit a 1 mL barrel.
- What dose does the FDA label actually state?
- The Depo-Testosterone label states that for replacement in the hypogonadal male, 50 to 400 mg should be administered every two to four weeks, and that dosage is adjusted according to the patient’s response and the appearance of adverse reactions. It specifies intramuscular use only.
- Why do some prescribers split the dose weekly instead of every two weeks?
- Testosterone esters in oil are absorbed slowly from the lipid phase, which is why the label permits two-to-four-week intervals. Some prescribers use shorter intervals to narrow the peak-to-trough swing. That is a clinical judgement your prescriber makes; it is not specified on the label.
- Can testosterone cypionate be injected subcutaneously?
- The Depo-Testosterone label specifies intramuscular use only. Subcutaneous administration of testosterone cypionate is used in some practices and is documented in the literature, but it is not the labelled route — ask your prescriber rather than changing route on your own.
- Does this page tell me what dose to take?
- No. It converts a dose your prescriber has already set into the volume and syringe units you draw, and it quotes the labelled range. Selecting a dose requires confirmed hypogonadism, your lab values, and clinical supervision.
Sources
- [1]FDA label — DEPO-Testosterone (testosterone cypionate) injection, Pharmacia & Upjohn (DailyMed SPL)
- [2]Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715–1744
- [3]FDA — Testosterone postmarket drug safety information for patients and providers
Related
This page is educational reference, not medical advice, and does not create a clinician–patient relationship. Dosing decisions belong to your prescriber.