HGH (human growth hormone) is taken as a subcutaneous injection, typically once daily in the evening, using a small needle inserted just beneath the skin. It’s a prescription medication approved for specific conditions like growth hormone deficiency, and the process involves proper preparation, correct injection technique, consistent site rotation, and refrigerated storage. Here’s what the full routine looks like.
When and How Often to Inject
Your body naturally releases its largest burst of growth hormone within minutes of entering deep sleep during the first part of the night. Evening injections, usually between 8:00 and 9:00 PM, are the traditional recommendation because they mimic this natural pattern. The injected hormone peaks about 4 to 6 hours later, aligning with the midnight-to-2:00 AM window when your body would normally produce its biggest surge.
That said, there’s a trade-off. Exogenous HGH stays in your bloodstream for 10 to 16 hours after injection, and during that time it suppresses your body’s own signaling molecules that promote deep sleep. Some researchers have proposed that morning injections may actually allow better sleep quality by letting natural hormone signaling resume before bedtime. In practice, most prescribers still recommend evening dosing, but if you notice sleep disruption, it’s worth discussing timing with your doctor.
Standard HGH (somatropin) is injected once daily. Newer long-acting formulations are dosed once weekly, which reduces the number of injections from roughly 365 to 52 per year.
Mixing Powdered HGH
Some HGH products come as a freeze-dried powder that you reconstitute before use. Others come premixed in pen devices and need no preparation. If you’re working with a powdered vial, the process matters because rough handling destroys the protein.
Wipe the rubber stopper on the vial with an alcohol swab. Draw up the correct amount of bacteriostatic water (a sterile water preserved with 0.9% benzyl alcohol) into a syringe. Insert the needle into the vial and aim the stream of water against the glass wall, not directly onto the powder. Then swirl the vial gently in a circular motion until the powder dissolves completely. Never shake it. Shaking breaks apart the protein molecules and creates a cloudy solution that should not be injected.
Once mixed, the solution should look perfectly clear. If it’s cloudy right after reconstitution, don’t use it. Small colorless particles can sometimes appear after refrigeration, which is normal for protein solutions, but cloudiness at the point of mixing means something went wrong.
Choosing a Needle
HGH is a subcutaneous injection, meaning it goes into the fat layer just under the skin, not into muscle. Short, thin needles work best. Research on subcutaneous injection technique has found that 32-gauge, 5-millimeter needles reliably reach the fat layer, cause minimal pain, and produce very little leakage from the injection site. For context, 32-gauge is one of the thinnest commercially available needle sizes. Thicker, longer needles (like 30-gauge, 8-millimeter) produce noticeably more pain during insertion.
If you’re using a pen device, the needles are usually sold separately and screw onto the pen tip. Your pharmacy or prescriber can recommend the right fit for your device.
Injection Sites and Rotation
There are eight possible injection sites on the body: the back of both upper arms, the top or outer area of both thighs, both sides of the belly (avoiding the navel area), and the outer upper quadrant of both buttocks. The standard recommendation is to use four of these eight sites and rotate through them with each injection. This prevents the fat layer beneath the skin from hardening or developing lumps, which can happen when the same spot is used repeatedly.
A simple approach is to keep a calendar or use the notes app on your phone to log which site you used each night. This makes rotation automatic rather than something you have to remember.
Storing HGH Properly
Both unmixed and reconstituted HGH need refrigeration at 36 to 46°F (2 to 8°C). Once you’ve mixed a powdered vial with bacteriostatic water, the solution stays good in the refrigerator for up to 14 days. Some cartridge formulations last up to 21 days refrigerated after reconstitution. Never freeze reconstituted HGH.
Premixed pen devices like Norditropin FlexPro have more flexibility. After first use, they can be stored either in the refrigerator for up to four weeks or at room temperature (up to 77°F) for up to three weeks. Prefilled single-dose syringes that haven’t been reconstituted can sit at room temperature for up to three months. These differences matter if you travel or don’t always have fridge access, so check the storage rules for your specific product.
How Dosing Is Adjusted
HGH dosing is individualized and adjusted over time based on blood work, not set to a fixed amount. For daily somatropin, starting doses are low and gradually increased. For the newer weekly formulation, adults under 60 typically start at 1.5 mg per week, while those 60 and older start at 1.0 mg per week. Women taking oral estrogen need higher starting doses (around 2.0 mg per week) because estrogen blunts the body’s response to growth hormone.
Doses are then adjusted in small increments, usually 0.5 to 1.5 mg at a time, until blood markers hit the target range. The maximum recommended weekly dose for the long-acting form is 8 mg. Your prescriber will check your IGF-1 level (a blood marker that reflects growth hormone activity) and growth hormone levels at around three months after starting treatment. Once levels stabilize, monitoring shifts to annual blood work.
Side Effects That Signal Too Much
The most common side effects of HGH therapy are swelling in the hands and feet, joint and muscle pain, and carpal tunnel syndrome (tingling or numbness in the fingers). These are dose-dependent, meaning they often improve when the dose is reduced. Fluid retention is usually the earliest sign that your dose is too high.
HGH also increases insulin resistance, which can push blood sugar levels up. People with existing risk factors for type 2 diabetes need closer monitoring. In men, breast tissue enlargement (gynecomastia) can occasionally occur.
Long-term excess growth hormone causes a condition called acromegaly, which involves thickening of bones, enlargement of the hands, feet, and facial features, and increased risk of high blood pressure and heart disease. This is why regular blood monitoring matters: it catches creeping elevations before physical changes occur. If you notice rings fitting tighter, shoes feeling snug, or increased joint stiffness, those are signs your levels may be running too high.
Who Can Legally Be Prescribed HGH
In the United States, HGH is FDA-approved for a specific set of conditions. In adults, the primary indication is growth hormone deficiency. In children, it’s approved for growth hormone deficiency, Turner syndrome, Noonan syndrome, Prader-Willi syndrome, SHOX deficiency, chronic kidney insufficiency, idiopathic short stature, and children born small for gestational age who don’t catch up in height. Using HGH outside these approved indications, including for anti-aging or bodybuilding purposes, is illegal under federal law. It is the only hormone with this specific legal restriction in the U.S.