HCG: Reference Overview and Reconstitution Notes

HCG (human chorionic gonadotropin) is a protein-based hormone studied in reproductive and endocrine (hormone system) research. It is FDA-approved for specific reproductive and hormone-related uses.

HCG

What it is

HCG (human chorionic gonadotropin) is a hormone made of protein. It belongs to a group called gonadotropins (hormones that act on the reproductive system). The body naturally makes it in the placenta. It is built from two pieces that join together, called the alpha subunit and the beta subunit. Think of them like two puzzle pieces that snap together to form one working hormone.

The alpha subunit looks a lot like the matching piece found in two other reproductive hormones, LH and FSH, which are made in the brain's pituitary gland. The beta subunit is what makes HCG unique. It gives HCG its own identity and determines what signal it sends.

Key point: HCG is a delicate protein hormone. At the lab bench, it must be handled gently and never shaken. Once mixed with liquid, it must be kept in the refrigerator at 2 to 8 degrees Celsius.

Research context and categorization

HCG falls under the reproductive and endocrine (hormone system) research category. Its activity is very similar to a hormone called LH (luteinizing hormone), so it is often studied in connection with how the reproductive organs receive signals in both sexes.

Research Applications

• In females, it is studied for its role in triggering the final stages of egg development and the release of an egg (ovulation). This includes research related to assisted reproduction workflows.
• In males, it is investigated for how it prompts the testes to produce steroid hormones. It is also discussed in relation to the body's own testosterone signaling and the support of sperm production.
• It is also referenced in research on undescended testicles before puberty (cryptorchidism), specifically cases not caused by a physical blockage.

Weight Regulation Claims

HCG has been marketed for weight loss. However, the FDA has stated there is no solid evidence that HCG works for weight loss. The FDA has warned against over-the-counter HCG products sold for that purpose. That use is not confirmed or approved.

Status

• Regulatory status: HCG is FDA-approved for specific uses. These include helping trigger ovulation in certain women who have trouble conceiving, treating undescended testicles before puberty when no physical blockage is present, and certain cases where the body does not make enough of its own reproductive hormones (hypogonadotropic hypogonadism) in males. It is a prescription product for these approved uses, not a research-only compound.
• Sport status: HCG is banned under the WADA Prohibited List (the World Anti-Doping Agency's list of banned substances). Chorionic gonadotropin (CG) and luteinizing hormone (LH), along with substances that trigger their release, are listed in class S2 (peptide hormones, growth factors, related substances and mimetics). They are banned in males at all times, both in and out of competition.

Reconstitution notes (general)

HCG is usually supplied as a lyophilized powder (freeze-dried, similar to instant coffee) that must be mixed with bacteriostatic water before lab use. To find the final concentration, divide the total units in the vial by the milliliters of water added.

For example, a 5,000 IU vial mixed with 2 mL of water gives 2,500 IU per mL. A 10,000 IU vial mixed with 10 mL gives 1,000 IU per mL. Use the calculator at peptide calculator to figure out concentration from vial units and water volume.

Dilution and handling notes (compound-specific)

HCG is measured in international units (IU), not milligrams. Vials are commonly labeled 5,000 IU or 10,000 IU. The amount of water you add sets the working concentration of the final solution.

A common starting point is about 1 mL of bacteriostatic water per 1,000 IU. Depending on the concentration needed, this usually means adding somewhere between 2 mL and 10 mL of water per vial.

Bacteriostatic water is water that contains about 0.9 percent benzyl alcohol as a preservative. Think of benzyl alcohol like a preservative that keeps bacteria from growing in the vial. It is preferred over plain sterile water because the mixed vial is stored and drawn from more than once, rather than used all at once.

Reconstitution and Mixing Technique

The powder usually dissolves easily and does not need aggressive mixing. The right technique is to aim the liquid slowly at the inner glass wall of the vial rather than directly onto the powder. Then swirl the vial gently until the liquid becomes clear.

The most important thing to remember is that HCG is a delicate protein and must not be shaken. Hard shaking can cause foaming and can damage the protein structure, which may reduce how well it works. Gentle swirling is always the right approach.

A properly mixed vial should be clear and colorless. If the solution looks cloudy, has changed color, feels gel-like, or has visible particles floating in it, something is wrong. Such a vial should be discarded rather than used.

Handling and storage

• Keep mixed HCG refrigerated at 2 to 8 degrees Celsius and protect it from direct light.
• Wipe the rubber stopper with alcohol before each use. Write the mix date on the vial label so you always know how old it is.
• As a general guideline, a mixed vial lasts about four weeks in the refrigerator. Potency (strength) drops over time.
• Discard any vial that has gone cloudy, changed color, or has particles floating in it.
• Unmixed freeze-dried powder is generally stored at normal room temperature until reconstitution (mixing), following the specific product's label instructions.

Related reading

• HMG (Menotropins)
• Liraglutide
• Melanotan I
• How Reconstitution Works
• How Long Does a Reconstituted Vial Last?

Tools and supplies

• peptide calculator
• Bacteriostatic Water 30 ml
• Gansulin Metal Reusable Pen
• 3 ml Glass Cartridges (10-pack)
• Complete Starter Kit

Reminder: research and educational reference only. Preppin Peppers sells hardware and materials, not peptides. Not medical, dosing, or health advice, not evaluated by the FDA, and not intended for human or animal use.

Frequently asked questions

What is the chemical structure of HCG?

HCG is a glycoprotein hormone composed of two subunits: an alpha subunit structurally similar to LH and FSH, and a unique beta subunit that defines HCG's distinct receptor-binding identity.

How is HCG lyophilized powder reconstituted for laboratory use?

Add bacteriostatic water to the vial and swirl gently , never shake. Divide total IU by water volume added to find concentration (e.g., 5,000 IU ÷ 2 mL = 2,500 IU/mL). Refrigerate at 2-8 °C after mixing.

Is HCG listed on the WADA Prohibited List?

Yes. WADA classifies chorionic gonadotropin (CG) under S2 (peptide hormones, growth factors, related substances and mimetics) and prohibits it in males at all times, both in and out of competition.

More in our bacteriostatic water and diluents collection.

What the research community gets wrong about HCG

HCG comes up a lot in bench notes, and a few ideas get repeated that do not hold up. Here are the ones worth correcting.

• It is not just "the same as LH." The alpha subunit of HCG does match the one in LH and FSH, but the beta subunit is different and gives HCG its own identity. Keep reference material and labeling for LH and HCG separate so vials do not get mixed up.
• HCG is measured in international units, not milligrams. A lot of concentration mistakes come from treating an IU vial like a milligram vial. To find the working strength, divide total IU by the milliliters of water added (for example, 5,000 IU in 2 mL is 2,500 IU per mL). There is no clean mass conversion to reach for.
• "HCG" is not one single molecule. Depending on how it was produced (urinary versus recombinant), a preparation can carry different glycoforms, such as regular HCG, hyperglycosylated HCG, and free beta subunit. Two vials with the same label are not guaranteed to behave identically, so record the source and lot in your notes.
• The freeze-dried powder is not indestructible. It is a glycoprotein, and rough shaking, heat, and light degrade it. Aim water at the inner glass wall, swirl gently, and keep the mixed vial cold and dark. Foaming is a warning sign, not a sign of good mixing.
• The "weight loss" story is marketing, not a research result. The FDA has stated there is no solid evidence HCG works for weight loss and has warned against products sold that way. That claim does not belong in a lab reference and should not shape how you catalog or study the material.

From our bench: If you have reconstituted an HCG vial, tell us what you actually saw. Which bacteriostatic water volume did you add per vial, about how long did the powder take to go fully clear with gentle swirling, and how many days did the mixed vial stay clear and colorless in the refrigerator before you noticed any change? Share your real measurements and observations, not numbers from a label.

Sources

1. Bacteriostatic Water for Injection, USP , FDA/DailyMed label (0.9% benzyl alcohol)
2. Duerkop et al., Biotechnol J 2018 , Impact of Cavitation, High Shear Stress and Air/Liquid Interfaces on Protein Aggregation
3. Sigma-Aldrich (Merck) , Handling and Storage Guidelines for Peptides and Proteins
4. Cole LA. New discoveries on the biology and detection of human chorionic gonadotropin. Reprod Biol Endocrinol. 2009 (PMC)
5. Kyhl et al. First-in-human trial of a novel recombinant human chorionic gonadotropin (CG beta) in healthy women and men. Clin Transl Sci. 2021 (PMC)
6. FDA Consumer Health Information: HCG Diet Products Are Illegal (FDA notice, 2011)