Vosoritide: evidence, FDA status and research

An injection that helps children with achondroplasia (a type of short stature) grow faster. In 121 children it added about 1.6 cm a year, but adult height gains are unproven.

Sold for

Vosoritide is the first drug that makes children with achondroplasia grow taller, an injection that reactivates stunted bone growth.

Studies say

One randomized trial showed about 1.6 centimeters per year of extra growth, with final adult height and effects on complications still unproven, which is why it holds an A under accelerated approval.

Why grade A. A 121-child randomized placebo-controlled phase 3 trial showed a 1.57 centimeter per year increase in growth velocity over 52 weeks, the basis for approval. The endpoint is a surrogate (growth rate, not final height or function), which the FDA addressed by granting accelerated approval. Grade A for the approved use given the randomized design and matching indication. ¹²

FDA. Vosoritide is approved by the FDA as Voxzogo (November 2021, accelerated approval) to increase linear growth in children with achondroplasia and open growth plates. Initially for ages 5 and up, the indication was extended in October 2023 to children of all ages with open epiphyses. Continued approval may depend on confirmatory evidence of final adult height. ²

Written from 2 cited sources. Fact-checked 2026-10-27: 15 claims checked, 2 corrected. Last refreshed 2026-10-27. Not physician reviewed.

What this means for you

What people take it for: Faster growth in children with achondroplasia.
Can a US doctor prescribe it?: Yes, FDA approved for children with achondroplasia whose bones are still growing.
Properly tested in people?: Yes, in large controlled trials: a 121-child trial.

Evidence checklist

Randomised controlled trial Placebo-controlled phase 3, 52 weeksyes
Human study over 100 people Phase 3 had 121 childrenyes
More than one research group Sponsor-run trials; extensions follow-upno information
Clinical outcomes, not surrogate markers Growth rate, not final height or functionno
Human safety data beyond case reports Trial and label data in childrenyes

Drawn from the cited studies below. A dash means the sources give no information.

What it is

Vosoritide is a 39-amino-acid analog of C-type natriuretic peptide (CNP), a signaling molecule that bone growth plates make themselves. Natural CNP is destroyed within minutes by an enzyme called neutral endopeptidase; vosoritide is modified to resist it so an injection under the skin keeps levels up for hours. BioMarin developed it. ¹²

Achondroplasia is the most common form of dwarfism, caused by a gain-of-function mutation in the FGFR3 gene that is a brake on cartilage growth. Average adult height is around 4 feet 4 inches for men and 4 feet 1 inch for women, and the condition brings spinal stenosis, sleep apnea and ear infections. Before vosoritide, the only options were limb-lengthening surgery and growth hormone, which has limited effect. ¹

How it works

In the growth plate, FGFR3 signaling through the MAPK pathway slows the cartilage cells that lengthen bone. CNP, acting through its receptor NPR-B, blocks that pathway at a downstream step. In achondroplasia FGFR3 is permanently switched on, so adding a stable CNP analog pushes back against the overactive brake and lets cartilage cells proliferate and mature closer to normal. The effect requires open growth plates, which is why the drug has no use after puberty ends. ¹²

What human research shows

The phase 3 trial, published in The Lancet in 2020, randomized 121 children aged 5 to under 18 with achondroplasia to vosoritide or placebo for 52 weeks. Annualized growth velocity increased by 1.57 centimeters per year in the vosoritide group relative to placebo (adjusted mean difference). Height z-score, a measure of height relative to peers, also improved. Body proportions did not change measurably within a year. ¹

Approval for younger children came from a randomized trial in infants and children under 5, and open-label extension data following the phase 3 participants for several years show continued growth above the untreated achondroplasia norm. Whether treated children reach a taller final height, or have fewer spinal and airway complications, is what the confirmatory follow-up is meant to answer. ²

Study	Model	Finding
Phase 3 trial (Savarirayan 2020, Lancet)	Humans, n=121 children aged 5 to 17 with achondroplasia, randomized placebo-controlled, 52 weeks	Growth velocity increased by 1.57 cm per year versus placebo with injection-site reactions and transient low blood pressure as the main side effects. ¹
Voxzogo prescribing information	FDA label, including trial in children under 5	Accelerated approval for all ages with open growth plates; confirmatory evidence of final height pending. ²

Safety

Injection-site reactions (redness, swelling, hives) were the most common adverse events, affecting most children at some point. Vomiting and transient drops in blood pressure with dizziness or nausea were more frequent than placebo in the phase 3 trial; the label advises giving the injection with food and fluids to reduce this. According to the label, two children on vosoritide stopped treatment because of pain and anxiety with the injections, and 8 of 60 had transient drops in blood pressure against 3 of 61 on placebo. ¹²

The label notes that growth plate closure should be confirmed before stopping, and that the drug is not expected to work after the plates have fused. Long-term effects on bone quality, blood pressure and other CNP-responsive tissues are being tracked in extension studies. ²

Questions for your clinician

Does final adult height improve with treatment?
How are low blood pressure and dizziness avoided?
When would growth plate closure end treatment?

Questions people ask

Is vosoritide FDA-approved?

Yes, as Voxzogo, under accelerated approval since November 2021 for children with achondroplasia and open growth plates. Since October 2023 it covers all ages, down to infancy. Continued approval depends on confirming that faster growth translates into greater adult height. ²

How much taller do children get?

In the 121-child phase 3 trial, treated children grew about 1.6 centimeters per year more than those on placebo over one year. Projections over a full childhood come from extension data, not from completed trials, and final adult height outcomes are not yet published. ¹²

Why does it only work in children?

Vosoritide acts on cartilage cells in the growth plates at the ends of long bones. Once those plates fuse at the end of puberty there is nothing for it to act on. ¹²

What reactions do children usually have?

Injection-site reactions in most children, plus vomiting and brief episodes of low blood pressure with dizziness. Taking the injection with food and fluids reduces the blood pressure effect. In the phase 3 trial two children on vosoritide stopped because of injection pain and anxiety. ¹²

Citations

Savarirayan 2020, Lancet: Once-daily subcutaneous vosoritide in children with achondroplasia, randomized phase 3 trial doi.org
FDA 2024: Voxzogo (vosoritide) prescribing information accessdata.fda.gov