Skytrofa is a brand-name injection prescribed for growth hormone deficiency (GHD) in children. Skytrofa contains the active ingredient lonapegsomatropin and belongs to the growth hormone drug class.

Skytrofa is approved by the Food and Drug Administration (FDA) to treat growth hormone deficiency (GHD) in certain children. With GHD, children don’t grow as expected because their bodies don’t make enough growth hormone.

Specifically, Skytrofa is approved for children ages 1 year and older who weigh at least 11.5 kilograms (kg), which equals about 25 pounds (lbs).

Drug details

You’ll find key information about Skytrofa below.

  • Drug class: growth hormone
  • Drug form: powder in single-dose prefilled cartridges that you’ll load into an autoinjector device to give as a subcutaneous injection
  • Generic available? no
  • Prescription required? yes
  • Controlled substance? no
  • Year of FDA approval: 2021

Skytrofa is available only as a brand-name medication. It’s not currently available in generic or biosimilar form. A biosimilar medication is a drug that’s similar to a brand-name biologic drug (the parent drug). Skytrofa is a biologic medication, which is also called a biologic.

Biologic drugs are made from living cells. It’s not possible to copy these drugs exactly. A generic, on the other hand, refers to drugs made from chemicals. A generic is an exact copy of the active ingredient in a brand-name medication.

Biosimilars are considered to be just as safe and effective as their parent drug. And like generics, biosimilars tend to cost less than brand-name medications.

The Skytrofa dosage your doctor prescribes will depend on several factors. These include:

  • child’s body weight
  • how your child responds to Skytrofa treatment

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Skytrofa comes in single-dose prefilled cartridges. Each cartridge has two chambers: one contains the drug power and one contains sterile water.

Skytrofa is available in several strengths:

  • 3 milligrams (mg)
  • 3.6 mg
  • 4.3 mg
  • 5.2 mg
  • 6.3 mg
  • 7.6 mg
  • 9.1 mg
  • 11 mg
  • 13.3 mg

Dosage for growth hormone deficiency in children

Skytrofa treats GHD in children ages 1 year and older who weigh at least 11.5 kilograms (kg). (1 kg equals about 2.2 pounds [lbs]). The recommended dosage of Skytrofa is 0.24 milligrams per kilogram of body weight (mg/kg), given once weekly.

The recommended dosage is the same for children starting growth hormone treatment for the first time and for children who previously received daily injections of somatropin. If your child previously had daily somatropin injections, wait at least 8 hours between the last dose of somatropin and the first dose of Skytrofa.

The table below summarizes the usual doses of Skytrofa based on the recommended dose of 0.24 mg/kg per week.

Body weight (kg)Body weight (lbs)Dose
11.5–13.9 kg about 25–31 lbs3 mg
14–16.4 kgabout 31–36 lbs3.6 mg
16.5–19.9 kgabout 36–44 lbs4.3 mg
20–23.9 kg about 44–53 lbs5.2 mg
24–28.9 kg about 53–64 lbs6.3 mg
29–34.9 kgabout 64–77 lbs7.6 mg
35–41.9 kgabout 77–92 lbs9.1 mg
42–50.9 kg about 92–112 lbs11 mg
51–60.4 kgabout 112–133 lbs13.3 mg
60.5–69.9 kgabout 133–154 lbs15.2 mg (given as two 7.6-mg injections)
70–84.9 kg about 154–187 lbs18.2 mg (given as two 9.1-mg injections)
85–100 kgabout 187–220 lbs22 mg (given as two 11-mg injections)

Your child’s doctor may recommend a different dosage depending on your child’s response to treatment and treatment goals. In this case, your doctor will likely round the dose to the closest available strength of Skytrofa.

How to inject

Skytrofa comes as single-dose prefilled cartridges. The cartridge has two chambers; one contains the drug power and one contains sterile water. To administer Skytrofa, you’ll load a cartridge into the Skytrofa autoinjector device. This device automatically mixes the drug, and you use it to inject the drug under the skin (subcutaneous injection).

A healthcare professional will show you how to use the Skytrofa autoinjector at home. The manufacturer’s website also provides helpful resources, such as step-by-step instructions and videos.

You’ll inject Skytrofa into the abdomen, buttock, or thigh. Be sure to rotate your injection site for each injection. If you inject the same spot repeatedly, skin lumps or pitting can occur.

About using Skytrofa

Below you’ll find information about key dosage issues.

  • When to take: You should take Skytrofa once weekly. Using the medication on the same day each week helps maintain a steady level of the drug in your body. This helps Skytrofa work effectively.
  • If you miss a dose: If you miss a dose of Skytrofa, administer it as soon as possible within 2 days. If more than 2 days have passed since you missed your dose, skip the missed dose. Then administer your usual dose on the next scheduled day. Always wait at least 5 days between doses.
  • Taking Skytrofa with food:The timing of food does not affect Skytrofa.
  • Length of use: Skytrofa is usually a long-term treatment during childhood. Children should use it for as long as they are still actively growing. Once your child stops growing taller (when epiphyseal fusion occurs, also known as closed growth plates), your child will stop using Skytrofa. Your doctor will recommend exactly when to stop Skytofa, usually during puberty.
  • Length of time to work: Skytrofa starts working soon after you take the first dose. But it may take several months or a year to determine how well the medication is working. Keep in mind that Skytrofa helps to increase skeletal (bone) growth in children with growth hormone deficiency (GHD), and skeletal growth takes time. Your child’s doctor will routinely check their height at every office visit to monitor their growth rate.


Using more than the recommended dosage of Skytrofa can lead to serious side effects. Do not use more Skytrofa than your doctor recommends.

Overdose symptoms

Symptoms of an overdose can include:

Long-term overuse of growth hormones, such as Skytrofa, may result in gigantism. Symptoms of gigantism may include:

  • overgrowth of long bones, resulting in above-average height and weight
  • enlarged hands, feet, muscles, and organs
  • changes in facial features
  • delayed puberty
  • irregular periods
  • vision problems

What to do in case of overdose

If you think you’ve used too much of this drug, call your doctor. You can also call America’s Poison Centers at 800-222-1222 or use its online tool. However, if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

As with all medications, the cost of Skytrofa can vary. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Financial and insurance assistance:If you need financial support to pay for Skytrofa, or if you need help understanding your insurance coverage, help is available.

A program called Ascendis Signature Access Program is available for Skytrofa. A co-pay program is also available. For more information and to find out if you’re eligible for support, call 844-442-7236 or visit the program website.

To learn more about saving money on prescriptions, check out this article.

Biosimilar version:Skytrofa is not available in a generic or biosimilar form. A biosimilar medication is a drug that’s similar to a brand-name biologic drug (the parent drug). Skytrofa is a biologic medication, which is also called a biologic.

Biosimilars are considered to be just as safe and effective as their parent drug. And like generics, biosimilars tend to cost less than brand-name medications.

Here are answers to some frequently asked questions about Skytrofa.

How does Skytrofa work?

When you inject Skytrofa, your body converts it into somatropin. Somatropin is a synthetic (manufactured) version of human growth hormone. It works by replacing the growth hormone that’s normally released by the pituitary gland in the brain. Growth hormone is important for normal growth and development during childhood.

Children with GHD do not make enough of this hormone. This results in slowed growth and shorter stature. By replacing this hormone with weekly injections of Skytrofa, children with GHD may grow faster and taller.

Talk with your doctor or pharmacist if you have questions about Skytrofa’s mechanism of action.

How does Skytrofa compare to Norditropin?

Norditropin is a brand-name drug that contains the active ingredient somatropin. Somatropin is also known as recombinant human growth hormone. Doctors have been prescribing somatropin to treat GHD since the drug was approved in the 1980s. It’s usually given as a daily injection.

Skytrofa is a newer medication approved in 2021 for the treatment of GHD. Its long-acting design allows for less frequent injections.

The key difference between Norditropin and Skytrofa is the dosage schedule. With Norditropin, you have to inject your dose either every day or 6 days per week, while Skytrofa is a once-weekly injection. This schedule is more convenient for children and their caregivers.

To learn more about the similarities and differences between Skytrofa and Norditropin, talk with your doctor or pharmacist.

Is Sogroya similar to Skytrofa?

Yes, somapacitan (Sogroya) and Skytrofa are similar medications. Both are FDA-approved to treat GHD.

Both medications are given once weekly as subcutaneous injections. These medications also cause similar side effects.

However, the approved age ranges differ with each drug. Sogroya is approved to treat GHD in adults and children ages 2.5 years and older. Skytrofa is approved to treat this condition in children ages 1 year and older who weigh at least 11.5 kilograms (kg), which equals about 25 pounds (lbs).

Talk with your doctor to determine if one of these medications may be right for you.

Skytrofa can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Skytrofa. These lists do not include all possible side effects.

For more information about the possible side effects of Skytrofa, talk with your doctor or pharmacist. They can give you tips on how to manage any side effects that may concern or bother you.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Skytrofa, you can do so through MedWatch.

Mild side effects

Below is a partial list of mild side effects of Skytrofa. To learn about other mild side effects, talk with your doctor or pharmacist, or view Skytrofa’s prescribing information.

Mild side effects of Skytrofa can include:

  • viral infection, such as colds
  • fever
  • cough
  • nausea or vomiting
  • bruising and minor bleeding, such as nosebleeds
  • diarrhea
  • abdominal pain
  • joint pain or swelling

Most of these side effects may go away within a few days to a couple of weeks. However, if they become more severe or don’t go away, talk with your doctor or pharmacist.

Serious side effects

No serious side effects occurred during Skytrofa’s clinical trials. However, serious side effects have been reported with somatropin. Skytrofa is a prodrug of somatropin, which means Skytrofa converts into somatropin after you inject it. So, serious side effects of somatropin could possibly occur with Skytrofa.

Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

  • intracranial hypertension (increased pressure in the brain) with papilledema (swelling of the optic nerve), which may cause symptoms such as:
    • vision changes
    • headache
    • nausea and vomiting
  • slipped capital femoral epiphysis, which may include symptoms such as:
    • pain in the hip or knee that doesn’t go away
    • limping
    • difficulty walking
  • pancreatitis, which may include symptoms such as:
    • sudden, intense abdominal pain
    • swelling in your upper abdomen
    • nausea, vomiting, or diarrhea

For some people, Skytrofa injection can cause an allergic reaction.

This side effect didn’t occur during Skytrofa’s clinical trials, but severe allergic reactions have been reported since the drug’s approval.

In general, symptoms of allergic reaction can be mild or serious. You can learn more about possible symptoms in this article.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Skytrofa or somatropin injections, your doctor may recommend taking a different medication instead.

The Food and Drug Administration (FDA) approves prescription drugs such as Skytrofa to treat certain conditions. Skytrofa may also be used off-label for other conditions. Off-label drug use is when a doctor prescribes an FDA-approved drug for a purpose other than what it’s approved for.

Skytrofa for growth hormone deficiency in children

Skytrofa is FDA-approved to treat growth hormone deficiency (GHD) in children. With GHD, children don’t grow as expected because their bodies don’t make enough growth hormone.

Skytrofa is specifically approved for children ages 1 year and older who weigh at least 11.5 kilograms (kg), which equals about 25 pounds (lbs).

Growth hormone is essential for growth and development. It is normally released into the blood by the pituitary gland in the brain.

Skytrofa is a medication that converts into somatropin in the body, which is a synthetic version of human growth hormone. It treats children with GHD and aims to help them grow faster and taller.

Skytrofa can interact with several other medications. It can also interact with certain supplements and foods.

Before taking Skytrofa, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

Interactions with medications

Below is a list of medications that can interact with Skytrofa. This list does not contain all drugs that may interact with Skytrofa. If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

  • corticosteroids, such as prednisone (Rayos) and cortisone
  • oral estrogens, such as conjugated estrogens (Premarin) or estradiol (Estrace)
  • insulin, such as insulin lispro (Humalog) or insulin glargine (Lantus)
  • other diabetes medications, such as metformin (Glumetza, Riomet, others)
  • medications that certain liver enzymes break down, such as atorvastatin (Lipitor), fentanyl, and numerous others

Alcohol interaction

Alcohol is not known to interact with Skytrofa.

However, children should not consume any amount of alcohol. (Skytrofa is only approved for use in certain children.)

Other drugs are available that can treat your condition. If you’re interested in finding an alternative to Skytrofa, talk with your child’s doctor. They can tell you about other medications that may work well for your child.

The following drugs are similar to Skytrofa:

  • somapacitan (Sogroya)
  • somatrogon (Ngenla)
  • somatropin (Norditropin, Genotropin, Omnitrope, others)

If you can become pregnant, consider the following information about pregnancy and breastfeeding.

Skytrofa and pregnancy

It is unknown whether you should use Skytrofa during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before using this medication.

Skytrofa and breastfeeding

It is unknown whether you should use Skytrofa while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before using this medication.

This drug comes with several precautions.

Before taking Skytrofa, discuss your health history with your doctor. Skytrofa may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

  • acute (sudden or short-term) critical illness after major surgery or trauma
  • acute respiratory failure
  • epiphyseal fusion (closed growth plates), which refers to children who’ve stopped growing taller
  • active cancer
  • history of cancer
  • diabetic retinopathy
  • Prader-Willi syndrome, especially in those with obesity or severe breathing problems, such as sleep apnea
  • diabetes, prediabetes, or glucose (sugar) intolerance
  • hormone problems, including underactive thyroid or adrenal problems
  • scoliosis (curved spine)
  • previous allergic reaction to this or a similar drug, such as somatropin (Norditropin)
  • pregnancy
  • breastfeeding

Note: For more information about the potential negative effects of Skytrofa, see the “Skytrofa side effects” section above.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.