Growth hormone is administered through subcutaneous injection, meaning a small needle delivers the medication into the fatty tissue just beneath the skin. Most people give themselves (or their child) these shots at home using a pen device or syringe, typically once daily. A newer weekly injection option is also available. The process is straightforward once you learn the basics of where to inject, how to prepare the medication, and how to store it properly.
Why Subcutaneous Injection
Early growth hormone therapy used intramuscular injections, delivering the medication deep into muscle tissue. Clinical comparisons showed that subcutaneous and intramuscular routes produce nearly identical peak hormone levels in the blood and the same growth outcomes over time. The key difference is comfort. When patients in clinical trials were given the chance to try both methods, they overwhelmingly preferred subcutaneous injections, reporting less pain and better long-term adherence to treatment.
Where to Inject
There are eight possible injection sites on the body, and you should rotate among at least four of them. The recommended areas are the back of the upper arms, the top or outer thighs, either side of the belly (avoiding the area directly around the navel), and the outer upper quadrant of the buttocks. These spots have enough fatty tissue to absorb the hormone effectively.
Rotating sites matters more than most people realize. Injecting into the same patch of skin repeatedly causes a condition called lipohypertrophy, where fat, protein, and scar tissue build up into a firm lump under the skin. These lumps aren’t just cosmetic. They can interfere with how well your body absorbs the medication, making doses less effective. Keeping a simple calendar or log of which site you used each night helps you stay on track.
When to Give the Injection
Evening injections were traditionally recommended because the body’s natural growth hormone release peaks during sleep. A randomized crossover trial in children with growth hormone deficiency compared two weeks of evening injections against two weeks of morning injections. Growth markers and sleep quality were comparable across both schedules, with no meaningful differences in total sleep time, sleep efficiency, or daytime alertness. The practical takeaway: pick a consistent time that fits your family’s routine. Consistency matters more than the specific hour.
Types of Delivery Devices
Growth hormone comes in several formats, and the device you use depends on which product your doctor prescribes.
- Pre-filled pen injectors are the most common option today. They contain a cartridge of liquid growth hormone with a dial to set the dose. You attach a small disposable needle tip, dial your dose, press a button, and the injection is done. These pens are designed for home use and require minimal preparation.
- Vials with syringes are the traditional format. Some products come as a freeze-dried powder that you mix with a liquid diluent before drawing the dose into a syringe. This approach requires a few extra steps but is otherwise straightforward.
- Needle-free jet injectors use high-pressure air to push a fine stream of medication through the skin without a needle. Clinical studies have shown comparable growth outcomes between needle-free devices and conventional pen injectors. These are sometimes preferred for children with strong needle anxiety.
Mixing Powder Formulations
If your growth hormone comes as a powder (lyophilized form), you’ll need to reconstitute it with a sterile diluent before each use. The process goes like this: clean the rubber tops of both vials with an alcohol swab, draw air into the syringe, inject that air into the diluent vial, then flip the vial upside down and withdraw all the liquid. Next, push the needle into the powder vial and inject the diluent slowly, aiming the stream against the glass wall to avoid creating foam.
The most important step is how you mix it. Swirl the vial gently until the powder dissolves completely. Never shake it. Growth hormone is a protein, and shaking can denature it, essentially breaking apart the molecular structure and making the medication less effective or inactive.
Storage Requirements
Growth hormone is a fragile protein that needs refrigeration. Store vials, cartridges, and pens at 36°F to 46°F (2°C to 8°C). Once a cartridge is reconstituted or opened, it remains stable for up to 28 days in the refrigerator. Do not leave it at room temperature for more than 30 minutes per day. Never freeze growth hormone, and keep it out of direct sunlight. If you’re traveling, a small insulated cooler with an ice pack works, but avoid letting the medication come into direct contact with ice.
Understanding Dosing Units
Growth hormone doses are expressed in either milligrams or International Units (IU), which can be confusing. The conversion is roughly 3 IU per 1 milligram. A typical adult starting dose is around 0.2 mg per day (about 0.6 IU). Children’s doses are calculated by body weight. Your prescriber sets the exact amount, and pen devices make it easy to dial the correct dose without doing any math yourself.
Weekly Injections
Daily injections have been the standard for decades, but a long-acting option now exists. The FDA approved a once-weekly subcutaneous injection for children with growth hormone deficiency in June 2023. In a 52-week trial of children ages 3 to 12, the weekly formulation produced comparable growth rates to daily injections. This option significantly reduces the number of injections from roughly 365 per year to 52, which can make a real difference for families managing treatment fatigue or needle anxiety in young children.
Disposing of Needles Safely
Used needles and pen tips go into an FDA-cleared sharps container immediately after each injection. A rigid, puncture-resistant plastic container with a secure lid works if you don’t have a commercial one. Fill it no more than three-quarters full, then seal it and dispose of it through your community’s sharps program. Options vary by location but typically include drop-off sites at pharmacies, hospitals, or fire stations, mail-back programs, and special waste pickup services. You can find local options by calling 1-800-643-1643. Never throw loose needles into household trash or recycling, and always use a fresh needle for each injection to reduce infection risk and prevent lipohypertrophy.