Short answer: In the label's pediatric trial, the most common Skytrofa side effects were viral infection (15% vs 11% on daily somatropin), fever (15% vs 9%), cough (11% vs 7%), nausea and vomiting (11% vs 7%) and bleeding such as nosebleeds or bruising (7% vs 2%). In adults, the most common was swelling (edema), 8% vs 1% on placebo. There is no boxed warning.
What Skytrofa is approved for: Skytrofa is a once-weekly growth hormone approved for children 1 year and older who weigh at least 11.5 kg and have growth failure from growth hormone deficiency, and to replace growth hormone in adults with growth hormone deficiency (section 1).
Source
SKYTROFA (lonapegsomatropin-tcgd) for injection, for subcutaneous use, prescribing information. Ascendis Pharma. DailyMed, version published October 26, 2026. DailyMed setid 9229f871-bc61-4ddc-8122-d126d40e36ac
No. The current Skytrofa label has no boxed warning.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Skytrofa.
| Adverse reactions | Daily Somatropin (N = 56) n (%) | Skytrofa (N = 105) n (%) |
|---|---|---|
| Infection, viral | 6 (11%) | 16 (15%) |
| Pyrexia | 5 (9%) | 16 (15%) |
| Cough | 4 (7%) | 11 (11%) |
| Nausea and vomiting | 4 (7%) | 11 (11%) |
| Hemorrhage | 1 (2%) | 7 (7%) |
| Diarrhea | 3 (5%) | 6 (6%) |
| Abdominal pain | 2 (4%) | 6 (6%) |
| Arthralgia and arthritis | 1 (2%) | 6 (6%) |
Children with growth hormone deficiency who had not been treated before, aged 3.2 to 13.1 years. Medically related reactions were grouped into one term. Hemorrhage on Skytrofa included nosebleeds (3), bruising (2), petechiae (1) and eye hemorrhage (1). Arthralgia and arthritis included joint pain (5) and reactive arthritis (1).
| Adverse reactions | Placebo (N = 84) n (%) | Skytrofa (N = 89) n (%) |
|---|---|---|
| Edema | 1 (1%) | 7 (8%) |
| Central (secondary) hypothyroidism | 1 (1%) | 6 (7%) |
Adults with growth hormone deficiency. Edema on Skytrofa included peripheral edema (6) and peripheral swelling (1). Central hypothyroidism included lab findings of low thyroid hormone; 5 of the 6 Skytrofa patients already had central hypothyroidism.
Children: more children on Skytrofa moved from normal to raised phosphate (44.2% vs 30.2% on daily somatropin) and alkaline phosphatase (19.2% vs 9.4%) by the end of the trial. These changes came and went.
Adults: more people on Skytrofa moved to raised alkaline phosphatase (14% vs 6% on placebo), more often as the trial went on.
Reported after approval: severe allergic reactions including anaphylaxis and angioedema, and osteonecrosis (bone death) in children.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Acute critical illness. Higher death rates have been reported in critically ill people after open heart or abdominal surgery, multiple injuries or acute respiratory failure given somatropin. Skytrofa is contraindicated in them, and the safety of continuing it in people who become critically ill has not been established.
Severe allergic reactions. Anaphylaxis and angioedema have been reported after approval with somatropin products, including Skytrofa. The label says prompt medical attention should be sought if an allergic reaction occurs.
Tumors. Active cancer can progress on somatropin, so any cancer must be inactive and its treatment complete first. Childhood cancer survivors treated with head or brain radiation had a higher risk of a second tumor, most often meningiomas. Moles are watched for growth or changes.
Blood sugar and diabetes. Somatropin may lower insulin sensitivity, especially at higher doses, and can unmask glucose intolerance or type 2 diabetes. Glucose is monitored, and diabetes medicine doses may need adjusting.
Raised pressure in the skull. Intracranial hypertension with swelling of the optic nerve, vision changes, headache, nausea or vomiting has been reported, usually within 8 weeks. An eye exam is done before starting and periodically after, and treatment is stopped if optic nerve swelling appears.
Fluid retention. Swelling, joint pain, muscle pain and nerve compression such as carpal tunnel syndrome may occur. These are usually temporary and dose dependent.
Low cortisol. People with or at risk of pituitary hormone deficiencies may develop low cortisol or unmasked secondary adrenal insufficiency, and those already on steroid replacement may need higher doses.
Thyroid. Untreated hypothyroidism can blunt the response, and central hypothyroidism may appear or worsen during treatment, so thyroid tests are done periodically.
Hip problems in children. Slipped capital femoral epiphysis, sometimes with bone death (osteonecrosis), has been reported with somatropin. A child who starts limping or has persistent hip or knee pain is evaluated.
Scoliosis. Existing scoliosis can progress during rapid growth, so it is monitored, though somatropin has not been shown to cause more scoliosis.
Pancreatitis. Pancreatitis has been reported in children receiving somatropin, and the risk may be greater in children than adults. It is considered in anyone with persistent severe stomach pain.
Fat loss at injection sites. Injecting in the same spot for a long time can cause lipoatrophy, so sites are rotated between and within regions.
Sudden death in children with Prader-Willi syndrome. Deaths have been reported after starting somatropin in children with Prader-Willi syndrome who had severe obesity, airway blockage or sleep apnea, or an unidentified respiratory infection. Skytrofa is not approved for growth failure from genetically confirmed Prader-Willi syndrome.
Lab tests. Alkaline phosphatase and phosphate may rise on Skytrofa, and parathyroid hormone may rise with somatropin.
Who should not use it. People with acute critical illness, allergy to somatropin or Skytrofa's ingredients, children whose growth plates have closed, active cancer, active proliferative or severe non-proliferative diabetic eye disease, and children with Prader-Willi syndrome who are severely obese or have severe breathing problems.
From the Patient Counseling Information (section 17); the label has an Instructions for Use but no separate Patient Information leaflet that comes with Skytrofa:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.