Veozah (Fezolinetant) for Girls Under 12: What Parents and Clinicians Need to Know About Transition to Adult Care

Why a Pediatric Article on a Menopause Drug Exists

Fezolinetant is a menopause drug. Full stop. The FDA approved Veozah in May 2023 solely for moderate-to-severe vasomotor symptoms caused by menopause in adult women. No child under 18 was enrolled in any registration trial, and no pediatric dosing has been established.

So why does a women's-health platform need to address girls under 12?

Three reasons:

1. Parents occasionally ask whether a hot-flush treatment they have read about could explain or treat symptoms in a daughter with a known hypothalamic condition.
2. Pediatric and adolescent gynecology patients with premature ovarian insufficiency (POI) or central precocious puberty (CPP) will grow into adult patients who may one day be candidates for this drug class.
3. Transition to adult care is a defined clinical process, and any girl whose hypothalamic-pituitary-ovarian (HPO) axis has been disrupted in childhood needs a provider who understands where fezolinetant fits, and where it does not, on the adult side of that transition.

This article is a roadmap for that transition, written for the parents of young girls, pediatric endocrinologists handing off patients, and adult women's health providers receiving them.

What Fezolinetant Actually Does: The Neuroscience That Matters for Girls

KNDy Neurons and the HPO Axis

Fezolinetant works by blocking the NK3 receptor on so-called KNDy neurons (neurons co-expressing kisspeptin, neurokinin B, and dynorphin) in the hypothalamic arcuate nucleus. In menopausal women, estrogen withdrawal causes KNDy neurons to become overactive, which drives the episodic hypothalamic temperature dysregulation experienced as hot flashes. Clinical trial data from the SKYLIGHT 1 and SKYLIGHT 2 trials showed fezolinetant reduced moderate-to-severe VMS frequency by approximately 60 percent versus placebo at 12 weeks.

KNDy neurons are not inert in childhood. They play a central role in the timing of puberty and in pulsatile GnRH secretion throughout reproductive life. This is why the NK3 pathway is biologically relevant, even in a 10-year-old girl who will never take fezolinetant.

Why This Mechanism Is Off-Limits Before Puberty

Blocking NK3 receptors before the HPO axis has matured carries theoretical risks that have not been studied because no responsible ethics board would approve such a trial. Kisspeptin-neurokinin B signaling is required for the pubertal GnRH pulse acceleration that initiates menarche. Experimental animal data suggest that disrupting this pathway during developmental windows can delay or alter pubertal timing. No human pediatric data exist for fezolinetant. None. The FDA prescribing information does not include a pediatric section because no studies have been conducted or are currently planned in this age group.

If a child under 12 has symptoms that sound like hot flashes, the correct clinical response is investigation, not fezolinetant.

Conditions in Girls Under 12 That Create a Future Fezolinetant Conversation

Premature Ovarian Insufficiency

POI affects approximately 1 in 10,000 women before age 20 and 1 in 1,000 before age 30. Girls diagnosed in childhood or early adolescence with POI from Turner syndrome, galactosemia, chemotherapy, or idiopathic causes face decades of estrogen deficiency. As adults, they will experience menopausal-equivalent VMS and other estrogen-withdrawal symptoms.

For most of these women, hormone therapy (HT) remains the first-line treatment for VMS and the standard of care for bone and cardiovascular protection through at least age 51, the average natural menopause age. Fezolinetant is not a replacement for HT in women with POI because it does not supply estrogen. ACOG guidance on POI makes clear that systemic estrogen replacement is the cornerstone of management for young women with this condition.

Where fezolinetant might eventually become relevant: a woman with a history of childhood POI who reaches her 40s or 50s, has completed her family, and prefers a non-hormonal option for residual or re-emerging VMS. That is an adult decision, not a pediatric one.

Central Precocious Puberty

Girls with CPP are treated with GnRH agonists to suppress the HPO axis. This treatment is deliberately designed to quiet KNDy-driven GnRH pulses. When GnRH agonist therapy ends and the HPO axis reactivates, most girls proceed through normal puberty and reproductive function. There is no evidence that fezolinetant has any role during or after CPP treatment. Mentioning it here only because CPP treatment directly involves the same hypothalamic circuit that fezolinetant targets in adults.

Hypothalamic Amenorrhea and Functional Hypothalamic Conditions

Girls with eating disorders, extreme athletic training, or stress-related HPO suppression have low kisspeptin and neurokinin B activity, the opposite hormonal state from menopause. Fezolinetant would be physiologically inappropriate and is not indicated.

Oncology Patients Facing Premature Menopause

Girls under 12 treated with gonadotoxic chemotherapy or pelvic radiation for childhood cancers face a high risk of POI and early menopause. The American Society for Reproductive Medicine estimates that chemotherapy agents such as cyclophosphamide and busulfan carry the highest ovarian toxicity risk. When these girls grow into adults, they may present to women's health clinicians with severe VMS. If HT is contraindicated because of the nature of their cancer (for example, hormone-sensitive breast cancer), non-hormonal options including fezolinetant become very clinically relevant. Transition planning for this population should explicitly flag future VMS management as a care agenda item.

Transition to Adult Care: A Clinical Framework for Girls Whose HPO Axis Has Been Disrupted

Transition from pediatric to adult care is not a single appointment. It is a process, and for girls with HPO-axis conditions, that process should include a dedicated "future reproductive and menopause health" conversation before the handoff is complete. The framework below is specific to fezolinetant-relevant conditions.

Step 1: Identify Girls Who Will Need Adult VMS Management

Any girl under 12 with a confirmed diagnosis of:

• POI (any cause)
• Gonadotoxic chemotherapy or radiation exposure affecting ovarian reserve
• Surgical oophorectomy or significant ovarian damage
• Turner syndrome or other X-chromosome abnormalities affecting ovarian function

...should have "future menopause management" listed as a long-term care agenda item in her pediatric record. This is not alarmist. It is preparation.

Step 2: Establish Baseline Reproductive Endocrine Data Before Transfer

The receiving adult provider needs to know:

• Age at diagnosis of POI or ovarian injury
• Current AMH level and antral follicle count if available
• Hormone therapy history: what formulation, dose, and duration
• Any prior VMS symptoms and how they were managed
• Bone density (DXA) results, given that estrogen deficiency in childhood accelerates bone loss

ACOG Committee Opinion 605 recommends bone density monitoring starting at the time of POI diagnosis in adolescents. This baseline is essential context for adult providers.

Step 3: Counsel on the HT-First Principle in Young Women With POI

Adult providers receiving these patients need to understand one non-negotiable point: fezolinetant does not replace estrogen. A 22-year-old woman with childhood-onset POI who is off HT and experiencing hot flashes needs HT reinstated, not fezolinetant. Her bones, cardiovascular system, and brain depend on estrogen in ways that a 54-year-old postmenopausal woman's do not, because she is decades away from the physiologically normal timing of estrogen withdrawal.

The Menopause Society's 2023 position statement on hormone therapy specifies that HT benefits generally outweigh risks for healthy women under 60 with bothersome VMS, and that women with premature menopause have an especially favorable benefit-to-risk ratio for systemic HT through at least age 51.

Step 4: Document Future Non-Hormonal Option Eligibility

When a woman with childhood-onset POI eventually reaches a point where HT is contraindicated, she becomes a candidate for fezolinetant. Flag this in her adult record. The most common scenario: a breast cancer survivor with a history of childhood-onset POI who needs non-hormonal VMS management. Fezolinetant's approval for this clinical setting is supported by SKYLIGHT 4 open-label safety data showing a 52-week safety profile in adults, though women with prior hormone-sensitive malignancies were excluded from registration trials and should be counseled accordingly.

Pregnancy and Lactation: A Required Conversation Even for Young Patients' Futures

Pregnancy

Fezolinetant is classified as contraindicated in pregnancy. Animal reproduction studies showed embryofetal toxicity at doses relevant to clinical exposure. No adequate human pregnancy data exist. Any woman of reproductive potential who is prescribed fezolinetant must use effective contraception during treatment. For a girl who has grown into an adult woman with POI, contraception counseling is nuanced: POI does not mean infertility. Spontaneous ovulation and unintended pregnancy occur in approximately 5 to 10 percent of women with POI over time, making reliable contraception essential if fezolinetant is used.

Stop fezolinetant at least two weeks before any planned conception attempt, though given the lack of human safety data, a longer washout is a reasonable clinical preference.

Lactation

No data exist on fezolinetant transfer into human breast milk, the drug's effect on milk production, or infant outcomes with exposure. The FDA label advises against use during breastfeeding. For the typical adult recipient of these patients, who may be managing a young woman in her 20s or 30s with POI, this is a real clinical question. Fezolinetant should not be used by a breastfeeding woman until human lactation data are available.

Contraception Requirements

Because fezolinetant carries embryofetal risk and because young women with POI may ovulate unpredictably, contraception counseling must be explicit every time this drug is considered. An IUD, implant, or other highly effective method is appropriate. Oral contraceptives can also provide the estrogen component that young POI patients need, making them a potentially preferred option for women who are not yet ready to transition to menopause-specific HT.

Who This Drug Is Right For, and Who It Is Not

Right for (in the transition context)

• Adult women (18 and older) who were girls with POI or gonadotoxic cancer treatment and who now have menopausal-equivalent VMS
• Women in this group for whom HT is contraindicated or declined, after explicit counseling about the HT-first principle
• Women who have completed childbearing or are using reliable contraception

Not right for

• Any girl under 18. The drug is not studied, not approved, and carries theoretical developmental risks in the immature HPO axis
• Women with active pregnancy or breastfeeding
• Women with severe hepatic impairment (Child-Pugh C): the FDA label contraindicates use in this group
• Women currently on moderate-to-strong CYP1A2 inhibitors, including fluvoxamine, ciprofloxacin, or high-dose caffeine supplements, because fezolinetant is metabolized by CYP1A2 and plasma concentrations rise significantly with inhibition

Sex-Specific Pharmacology: What Changes Across a Woman's Life

Fezolinetant's pharmacokinetics in adults show modest weight-related variation but no clinically significant differences by race or ethnicity in registration trial analyses. No pharmacokinetic data exist for anyone under 18.

Across the female life course, what changes is not the drug but the context:

• Premenarche and early puberty. The KNDy neuron system is developing. No drug exposure is appropriate or studied.
• Reproductive years. Fezolinetant is not indicated (no VMS from menopause) and carries embryofetal risk. Contraception is mandatory if used off-label.
• Perimenopause. VMS may begin years before the final menstrual period. SKYLIGHT trials enrolled women 40 to 65, so perimenopausal women with VMS are a studied population, though most participants were postmenopausal.
• Post-menopause. The approved, studied indication.
• Surgical or iatrogenic menopause from childhood. This is the transition population this article exists for. These women reach adulthood with decades of estrogen deficiency history and may eventually need non-hormonal VMS options.

The dose is 45 mg once daily regardless of reproductive status. No dose adjustment exists for menopausal stage.

The Evidence Gap: What We Do Not Know

Women have been historically underrepresented in early-phase drug trials, and children are almost always excluded. For fezolinetant, the pediatric evidence gap is total. No phase 1 pediatric pharmacokinetic study has been published. No case series of off-label use in girls exists. No regulatory agency has requested pediatric studies because the indication (menopausal VMS) is definitionally adult.

What is extrapolated versus directly studied:

| Claim | Status | |---|---| | Fezolinetant reduces VMS in postmenopausal women | Directly studied (SKYLIGHT 1, 2, 4) | | Fezolinetant is safe in 12-to-17-year-olds | Not studied | | Fezolinetant is safe in girls <12 | Not studied; theoretical developmental risk | | KNDy neurons are essential for puberty timing | Established in animal and human genetics research | | NK3 blockade delays puberty in prepubertal animals | Shown in rodent models; not studied in humans |

As WomanRx clinical reviewer Rachel Goldberg, MD, puts it: "The conversation we should be having with pediatric endocrinology colleagues is not 'can this girl take fezolinetant' but 'when this girl is 35 and asking about her hot flash options, who will have told her that estrogen is still her best friend, and when does the non-hormonal conversation start?' That handoff planning is what's missing from most transition protocols."

Monitoring Considerations for Adult Providers Receiving Pediatric Transition Patients

Girls who enter adult care with a history of HPO-axis disruption need a baseline workup before any VMS medication, including fezolinetant, is considered.

• Liver function tests. Fezolinetant carries a class-level hepatocellular signal. The FDA label requires LFT monitoring at baseline, 3 months, 6 months, and 9 months. Women with a history of childhood chemotherapy may have underlying hepatic vulnerability.
• Bone density. DXA at baseline in young women with POI, per ACOG guidance. Fezolinetant does not improve bone density; only estrogen or dedicated bone-active agents do.
• Cardiovascular risk. Women with childhood-onset estrogen deficiency carry elevated cardiovascular risk entering adulthood. Fezolinetant has no established cardiovascular benefit. HT, particularly transdermal estrogen, may reduce cardiovascular risk in this population per data from the DOPS trial.
• Mental health screen. Women with POI have elevated rates of depression and anxiety. Fezolinetant has no evidence base for mood symptoms. This screening belongs in the transition checklist regardless of VMS management choice.