What to Know About Zomacton (Somatropin)

Injectable Drug for Growth Hormone Deficiency

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Zomacton (somatropin) is an injectable medication approved by the U.S. Food and Drug Administration (FDA) for treating adults and children who have a deficiency of growth hormone. A lack of growth hormone can cause a variety of symptoms, including short stature in children and weight fluctuations in adults.

The medication stimulates physiological actions in the body that would normally occur in response to the hormone, such as bone, muscle, and skin growth in children and metabolism in adults and children.

Doctor measuring girl's height
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Growth hormone is produced in the pituitary gland, a tiny gland located in the brain. The hormone is released into the blood and flows throughout the body, where it activates a number of cellular functions, such as bone and muscle growth and physical repair. 

A growth hormone deficiency can lead to metabolic problems for adults, and it can cause slow growth and short stature in children. Blood tests can be used to measure the hormone and can help determine the cause of a deficiency.

Zomacton, which is produced using a human growth hormone gene, binds to cells in the body at the same binding site where growth hormone would normally bind. The medication then works to imitate the actions of growth hormone, stimulating a variety of cellular activities. For example, it mediates glucose and fat metabolism and it regulates proteins that speed up muscle and skin growth and lengthen the bones in growing children.

Use in Children 

Children can have growth hormone deficiencies as a result of certain medical conditions, and sometimes there is no identifiable cause for the hormone deficit. Zomacton can be used for the treatment of childhood growth hormone deficiency, even when a cause is not identified.

Approved uses in children:

Growth hormone deficiency: Zomacton can be used to treat slow growth or inadequate growth due to a deficiency of naturally produced growth hormone.

Turner syndrome: It is used for treating children who are shorter than expected due to Turner syndrome. This syndrome is a chromosomal defect in which girls have only one X chromosome instead of two X chromosomes. Girls who have Turner syndrome experience slow development and other developmental issues, such as delayed puberty and infertility or diminished fertility.

Short stature homeobox-containing gene (SHOX) deficiency: SHOX is a genetic condition in which a mutation on the X or Y chromosome results in developmental problems. It can affect boys or girls.

Small size at birth: Zomacton is approved for treating children who are short in stature because they were born small for gestational age (SGA) and didn’t catch-up on their growth by the age of 2 to 4 years old.

Idiopathic short stature: The drug is approved for treating children who are shorter than expected for age without a known medical cause or explanation. 

Use in Adults

Zomacton is used as a substitute for growth hormone in adults who have a growth hormone deficiency. This type of deficiency can occur as a result of disease, damage, or surgical removal of the pituitary gland.

Head trauma, a pituitary tumor, an infection in the brain, or a bleed in the brain can all damage the pituitary gland. Tumors such as craniopharyngioma and pituitary adenoma can have varied prognosis.

Children or adults who have growth hormone deficiency may also need to have treatments for the causative issue (such as surgery, radiation, or medication) in addition to treatment with Zomacton.

Some conditions that necessitate pituitary surgery or radiation can result in insufficient production and release of growth hormone from the pituitary gland.

Off-Label Uses 

This medication specifically replaces growth hormone, and it is not medically recommended for off-label use for conditions without a confirmed growth hormone deficiency.

This product and other versions of it have been misused in athletics, often with serious repercussions for athletes who take it when it is considered against the rules or banned by regulatory oversight for the sport.

There has been research into the use of growth hormone as an anti-aging product. Researchers have not found evidence supporting its use or safety for this purpose. 

Before Use 

This medication can exacerbate certain medical conditions. You should not use Zomacton if you have already had an allergic reaction to somatropin in the past. Because it is a hormone that has many effects, including effects on growth and metabolism, it may have an impact on several medical conditions.

If you already take Zomacton or are going to start, you should talk to your healthcare provider if you develop a severe illness, such as an infection.

Children and adults who have cancer or who recovered from cancer can have growth or recurrence of cancer in association with Zomacton, and close monitoring can help identify signs of cancer progression.

Caution and Monitoring 

When using this medication, you will have some monitoring of the potential effects of growth hormone.

  • Glucose levels: Your glucose levels should be monitored because this medication can decrease your insulin sensitivity, especially if you already have glucose intolerance or diabetes mellitus. 
  • Thyroid function: This medication can increase the risk of hypothyroidism (low thyroid function). This is a high risk for people who already have hypothyroidism or for women (who have or don’t have a diagnosis of hypothyroidism).
  • Cortisol levels: People who have hypoadrenalism (low adrenal function) can develop reduced serum cortisol levels and/or may need to use a higher dose of glucocorticoids due to the effects of Zomacton.
  • Scoliosis: Children who have scoliosis (an abnormal curve of the spine) may experience progression of the condition as a result of taking Zomacton.


This medication can cause serious problems in people who have certain medical conditions. According to the manufacturer, children who already have closed bone epiphysis (the bone growth has reached full completion) should not use Zomacton. 

Children who have Prader-Willi syndrome (a genetic disorder) and have obesity or breathing problems have a risk of sudden death when taking this medication. 

According to the manufacturer, people who have active cancer should not take Zomacton. And the manufacturer warns against taking this medication if you have diabetic retinopathy (a disease of the eye caused by diabetes).

Other Human Growth Hormones

Somatropin is available in a generic formulation. It is also available under the brand names Genotropin, Norditropin, and Humatrope. 


Zomacton is injected subcutaneously (under the skin). It can be injected into the back of the upper arm, abdomen, buttock, or thigh. The injection location should be changed following a rotating schedule rather than using the same area for more than one injection in a row. This allows the area to heal and helps prevent issues like tenderness or soreness.

All listed dosages are according to the drug manufacturer. Check your prescription and talk to your healthcare provider to make sure you are taking the right dose for you.

The medication comes in three forms:

  • A 5 milligram (mg) vial with a 5 milliliter (mL) vial of bacteriostatic 0.9% sodium chloride (preserved with benzyl alcohol)
  • A 10 mg vial with a syringe of 1 mL of bacteriostatic water (preserved with 0.33% metacresol), with a 25G reconstitution needle
  • A 10 mg vial with a syringe of 1 mL of bacteriostatic water (preserved with 0.33% metacresol), with a vial adapter

Your healthcare provider will prescribe your dose and will specify which form you should use when taking this medication.

The dose for children is weight-based, which means that it’s calculated based on a child’s weight. Also, the dose differs for each childhood condition. Adults can use a weight-based dose or a standardized dose. 


For children, the total weekly dose should be divided equally for three, six, or seven doses per week. Your child’s doctor will talk with you about the schedule that best suits your child’s situation.

  • Growth hormone deficiency: The dose ranges between 0.18 mg per kilogram (kg) of body weight per week to 0.3 mg per kg of body weight per week depending on the severity of the deficiency and the child’s age
  • Turner syndrome: The dose is up to 0.375 mg per kg of body weight per week
  • Idiopathic short stature: The dose is 0.37 mg per kg of body weight per week
  • Children with SHOX deficiency: The dose is 0.35 mg per kg of body weight per week 
  • Small for gestational age: The dose is up to 0.47 mg per kg of body weight per week


Adults can take a standardized dose or a weight-based dose of Zomacton. The standard dosing is started at 0.2 mg per day and increased every one to two months by 0.1 mg per day to 0.2 mg per day.

A weight-based prescription is started at 0.006 mg per kg of body weight per day and increased based on the symptoms, effects, and side effects to a maximum of 0.0125 mg per kg of body weight per day. The weight-based dosing of Zomacton is not recommended for adults who are obese. 


According to the manufacturer, the solution that is used for the delivery of this medication can cause severe life-threatening reactions in infants. When Zomacton treatment is used for infants, pregnant women, or women who are breastfeeding, the manufacturer recommends using the formulation reconstituting 5 mg of the medication with 0.9% sodium chloride or using the Zomacton 10 mg benzyl alcohol-free formulation.

Reconstitution and Injection

You may be injecting the medication for yourself or for a family member. Your medical team can show you how to do it.

You will have to reconstitute (mix) the medication according to the package instructions. If you have any questions about this process, be sure to check with your pharmacist to make sure that you are doing it right.

A subcutaneous injection is a shallow injection in which the needle is placed under the skin, often at a side angle rather than straight down into the skin. Generally, a short needle is provided for a subcutaneous injection.

In order to prevent an infection, you will need to cleanse the skin before placing the needle. And you have to cover the puncture site after the injection to prevent bleeding or contamination of the puncture site.

How to Take and Store 

Zomacton vials should be stored at a temperature of 36 F to 46 F (2 C to 8 C) before and after they are reconstituted and should not be frozen. 

After it is reconstituted, it will be stable for several weeks. Discard any medication that has been reconstituted for longer than the recommended duration.

Zomacton 5 mg will remain stable for 14 days after being reconstituted with bacteriostatic 0.9% sodium chloride and refrigerated at 36 F to 46 F (2 C to 8 C). 

Zomacton 10 mg will remain stable for 28 days after being reconstituted with bacteriostatic water and refrigerated at 36 F to 46 F (2 C to 8 C).

Side Effects

This medication is safe, but it can cause side effects even for people who do not have special risks or precautions. If you experience any side effects, it’s important that you discuss your symptoms with your practitioner. 


The most frequent side effects of Zomacton are not always severe, but you should discuss them with your healthcare provider. For example, an infection or hypothyroidism can cause consequences if left untreated, and will improve with timely treatment. 

According to the manufacturer, the most common side effects of Zomacton for adults and children include:

  • Upper respiratory infection
  • Fevers 
  • Throat inflammation 
  • Flu 
  • Headaches 
  • Ear infections 
  • Swelling 
  • Muscle or joint aches 
  • Tingling 
  • Carpal tunnel syndrome 
  • Hypothyroidism 
  • High blood sugar


Some of the less frequent side effects of Zomacton can be harmful for your long-term health. You should get prompt medical attention if you experience pain, fevers, chills, or any symptoms of the severe side effects.

Serious side effects include:

  • Allergic reaction: A severe allergic reaction that interferes with breathing is a medical emergency. Symptoms include shortness of breath, chest tightness, or sudden anxiety.
  • Swelling in the brain or the eye: This may develop within eight weeks of starting the medication. It can cause headaches or blurred vision, and may result in vision loss of untreated. This side effect can be diagnosed with a neurological evaluation and an eye examination. 
  • Hip dislocation in children: The capital femoral bone may slip out of place, causing leg pain and/or weakness. This can be stabilized to prevent further injury if diagnosed promptly.
  • Pancreatitis: Inflammation or an infection of the pancreas can cause fevers and abdominal pain. 

Warnings and Interactions

Zomacton can interact with several medications, potentially causing side effects or requiring a dose adjustment.

  • Insulin and medications used to treat high blood sugar: Your dose of diabetes medication may need to be adjusted when taking Zomacton. 
  • Estrogen: Women who use estrogen may need a higher than usual dose if also taking Zomacton. 
  • Glucocorticoids: If you take glucocorticoids for treatment of hypoadrenalism or any other condition, you may need an increased dose of your glucocorticoids due to interactions with Zomacton. 
  • Medications metabolized by cytochrome P450: The dose of these medications may need to be adjusted when taking Zomacton. Medications metabolized by this enzyme include Prozac (fluoxetine), phenobarbital, Tegretol (carbamazepine), and more.
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Melmed S. Pathogenesis and diagnosis of growth hormone deficiency in adults. N Engl J Med. 2019;380(26):2551-2562. doi:10.1056/NEJMra1817346

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By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.