How to Mix HCG for Testosterone Replacement Therapy.

Physician-reviewed hCG education

How to Mix hCG Safely

hCG often arrives as a powder that must be reconstituted before use. The exact diluent volume, final concentration, storage instructions and dose conversion depend on the specific product and prescription.

Medically reviewed by Dr. Timothy Mackey
Medical Director · Updated September 2026

Why hCG is supplied as a powder

Many hCG products are supplied as lyophilized powder because that form is more stable before reconstitution. A separate sterile diluent may be supplied by the manufacturer or pharmacy. Once the diluent is added, the medication becomes a liquid solution that must be handled and stored according to the specific product instructions.

Learn more about hCG therapy and how it may be considered in selected men with hypogonadotropic hypogonadism, fertility goals or certain TRT-related treatment plans.

What should you have before reconstituting hCG?

Your pharmacy should provide or identify the correct supplies. These commonly include the hCG vial, the correct sterile diluent, a sterile mixing syringe and needle, alcohol swabs, the appropriate administration syringe, and a sharps container.

Do not substitute a different diluent or alter the prescribed concentration unless specifically instructed by the pharmacist or prescriber.

General reconstitution principles

Wash and dry your hands and work on a clean surface. Confirm the medication name, vial strength and diluent before starting. Clean the rubber stoppers with alcohol and allow them to dry.

Using the sterile equipment provided or recommended, transfer the exact volume of diluent specified on the pharmacy label or manufacturer instructions into the hCG vial. Direct the diluent gently along the vial wall when possible. Once added, gently swirl or roll the vial until the powder is dissolved. Avoid vigorous shaking unless the product instructions specifically say otherwise.

The solution should be inspected before use. If it appears cloudy, discolored, contains unexpected particles or the vial is damaged, contact the pharmacy before using it.

Why the mixing volume matters

The amount of diluent determines the final concentration. That concentration is what allows the prescribed dose to be converted into a measurable syringe volume. Because vial strengths and prescribed concentrations vary, there is no single universal “units on the syringe” chart that is safe for every hCG prescription.

This is why the exact concentration should be written clearly on the pharmacy label or dosing instructions. If the dose is written in IU but the syringe is marked in units or milliliters, confirm the conversion with the pharmacy or prescribing office before injecting.

How should reconstituted hCG be stored?

Storage depends on the specific product. Many reconstituted hCG products require refrigeration, but temperature range and beyond-use time can differ by manufacturer and pharmacy preparation. Follow the storage instructions on your label exactly.

Do not assume that a compounded or reconstituted vial remains usable for a certain number of weeks simply because another hCG product does. If the beyond-use date is unclear, ask the dispensing pharmacy.

Safe injection basics

Use a new sterile syringe and needle for every injection and never share or reuse injection equipment. Clean the vial stopper before each puncture and follow the injection route and site taught by your clinician. Dispose of used sharps immediately in an approved puncture-resistant sharps container.

For broader injection-safety information, see our guide to safe hormone injection technique.

Common mistakes to avoid

• Using a mixing ratio copied from another patient's prescription.
• Using the wrong diluent.
• Guessing the IU-to-syringe conversion.
• Using a vial past the labeled beyond-use date.
• Leaving a product unrefrigerated when the label requires refrigeration.
• Reusing needles or syringes.
• Changing the dose or frequency without prescriber guidance.

hCG and testosterone therapy

The 2024 AUA/ASRM guideline advises against exogenous testosterone for men interested in current or future fertility. Adding hCG is not a guarantee of preserved sperm production. Discuss a fertility-directed plan with a reproductive specialist rather than assuming TRT plus hCG will protect fertility.

hCG is sometimes considered in men receiving testosterone because it acts at the testicular LH receptor and can support intratesticular testosterone production. It may be relevant when testicular function or fertility is an important treatment goal, but it is not automatically required for every man on TRT.

Men concerned about fertility should review our TRT and fertility guide and hCG vs. Clomid comparison.

Frequently asked questions

How much bacteriostatic water should I add to hCG?

Use only the amount specified for your exact product and prescription. Different vial strengths and desired concentrations require different volumes.

Can I use sterile water instead of bacteriostatic water?

Only if that is what the product labeling or dispensing pharmacy instructs. Different diluents have different intended uses and storage implications.

Should I shake hCG after mixing?

In general, gentle swirling is commonly recommended for reconstituted protein-based medications, but the instructions for your specific product control. Follow the label or manufacturer directions.

How long does mixed hCG last in the refrigerator?

The beyond-use period varies by product and pharmacy preparation. Use the date and storage instructions printed on your pharmacy label rather than a generic online timeframe.

How do I convert IU of hCG to syringe units?

The conversion depends entirely on the final concentration after mixing. If the pharmacy label does not clearly show the conversion, contact the pharmacy or prescribing clinic before injecting.

Medical and safety sources

• DailyMed: FDA labeling for prescription medications
• FDA: Safe Use of Sharps, Needles and Syringes
• AUA/ASRM Male Infertility Guideline

This article is educational. Follow the exact instructions supplied with your prescription and contact the dispensing pharmacy or prescribing clinician if any mixing, storage or dosing instruction is unclear.