Addyi (Flibanserin) in Adolescents Ages 12 to 17: Off-Label Use, Safety, and What Clinicians Need to Know

What Is Flibanserin and Who Is It Approved For?

Flibanserin is a non-hormonal, centrally acting agent approved by the FDA in August 2015 under the brand name Addyi for premenopausal adult women with acquired, generalized HSDD. The approval covered a specific, narrow phenotype: distressing low desire that is not attributable to a co-existing medical condition, relationship problem, or another medication. The FDA approval does not extend to postmenopausal women, men, or anyone under 18 years of age. [1]

Mechanism of Action

Flibanserin acts as a 5-HT1A receptor agonist and 5-HT2A receptor antagonist, with additional agonist activity at dopamine D4 receptors. This mixed receptor profile is thought to shift the balance between inhibitory serotonergic tone and excitatory dopaminergic/noradrenergic tone in areas governing sexual motivation. [2] The mechanism differs entirely from phosphodiesterase-5 inhibitors used in male sexual dysfunction.

The REMS Requirement

Because of its serious interaction profile, the FDA required a Risk Evaluation and Mitigation Strategy (REMS) at approval. The ADDYI REMS mandates that prescribers complete a certification program and that patients be enrolled before dispensing. [1] Pharmacies must also be certified. These requirements remain active as of 2025, and they apply regardless of patient age.

Why Age Matters Clinically

The adolescent brain continues myelination of the prefrontal cortex through approximately age 25. Agents that alter serotonin and dopamine signaling during this window carry theoretical risks that have not been studied for flibanserin specifically. No pediatric pharmacokinetic data exist for this drug. [3]

FDA Regulatory Status for Patients Under 18

The FDA has never approved flibanserin for any indication in pediatric patients. The original New Drug Application (NDA 022526) did not include any data from patients under 18, and no supplemental NDA has been filed to seek a pediatric indication. [1]

Pediatric Research Equity Act Obligations

Under the Pediatric Research Equity Act (PREA), sponsors may be required to conduct pediatric studies for drugs that could plausibly be used in children. The FDA granted a waiver for flibanserin because HSDD as a defined diagnostic category does not apply to prepubertal children, and the agency determined the condition does not exist in the pediatric population in a form warranting study. [4] That waiver does not constitute evidence of safety or efficacy in adolescents.

Off-Label Prescribing Under Federal Law

Physicians may legally prescribe approved drugs off-label in the United States. However, prescribing flibanserin to a patient aged 12 to 17 would constitute off-label use without any supporting pharmacokinetic, efficacy, or safety data from this age group. The American Academy of Pediatrics states that off-label prescribing in minors should rest on "the best available evidence," and where evidence is absent, extreme caution is warranted. [5]

REMS and Minor Patients

The ADDYI REMS patient enrollment form was designed for adult patients. Prescribing to a minor would require the prescriber to manage consent and assent procedures that the REMS was not built to accommodate, adding an additional layer of regulatory and ethical complexity. [1]

Clinical Trials: What the Evidence Base Actually Contains

Adult Key Trials

Two large randomized controlled trials, BEGONIA and VIOLET, formed the basis of the 2015 FDA approval. Pooled across the key program, flibanserin 100 mg nightly produced a statistically significant but modest increase in satisfying sexual events (SSEs) versus placebo. In the combined dataset of approximately 2,400 adult women, mean SSEs increased by roughly 0.5 per month above placebo. [6] The effect size was small enough that the FDA's advisory committee voted against approval twice before the agency approved the drug on a third cycle with the REMS condition.

No Adolescent Data Exist

A search of ClinicalTrials.gov for "flibanserin" yields no completed or ongoing trials enrolling patients under 18. [7] PubMed contains no peer-reviewed pharmacokinetic or efficacy studies in adolescents. This is not a gap that can be bridged by extrapolating adult data, because adolescent hepatic CYP3A4 activity, body composition, and CNS receptor density differ from adults in ways that affect both exposure and response.

What Absence of Data Means Clinically

Absence of trial data is not a neutral finding. It means no minimum effective dose has been established for this population, no maximum tolerated dose is known, and the adverse event profile in a developing CNS has never been characterized. Prescribing under these conditions places the entire burden of risk on the individual patient. [3]

Safety Profile: Adult Data and Adolescent-Specific Concerns

Black-Box Warning: Alcohol and CNS Depression

The most serious safety signal for flibanserin is the black-box warning for severe hypotension and syncope when the drug is combined with alcohol. [1] In a dedicated pharmacodynamic study of 25 adults, 4 of 23 subjects who consumed alcohol with flibanserin experienced syncope or presyncope. Adolescents aged 12 to 17 represent a population in which alcohol use, including unreported or episodic use, cannot be reliably excluded. The legal drinking age in the United States is 21, but the 2023 National Survey on Drug Use and Health found that approximately 15% of adolescents aged 12 to 17 reported past-month alcohol use. [8] That prevalence creates a clinically meaningful overlap risk.

CYP3A4 Drug Interactions

Flibanserin is primarily metabolized by CYP3A4. Moderate or strong CYP3A4 inhibitors, including fluconazole, ketoconazole, and several macrolide antibiotics commonly prescribed to adolescents, can raise flibanserin plasma concentrations several-fold. [2] A 6-fold increase in exposure was observed with the strong CYP3A4 inhibitor itraconazole in adult pharmacokinetic studies. Adolescents receiving treatment for acne (doxycycline), respiratory infections (clarithromycin), or fungal infections face a drug interaction risk that has not been characterized in their age group.

CNS and Neurodevelopmental Considerations

Flibanserin produces somnolence in roughly 11% of adult trial participants at the 100 mg dose. [6] Somnolence, dizziness, and fatigue were the most common adverse events leading to discontinuation in adult trials. In adolescents, whose sleep architecture and academic demands differ from adults, daytime sedation carries additional functional consequences. Chronic serotonin and dopamine receptor modulation during adolescence has been studied in the context of antidepressants, where post-marketing surveillance has revealed developmental signals not apparent in adult trials. [9] No analogous surveillance exists for flibanserin.

Cardiovascular Signal

A pooled safety analysis of flibanserin trials showed a small but measurable decrease in systolic blood pressure at peak concentration. [6] Adolescents with undiagnosed orthostatic hypotension, eating disorders, or low baseline blood pressure may be at disproportionate risk from this effect.

HSDD in Adolescents: Does the Diagnosis Apply?

Diagnostic Criteria and Age

HSDD as defined in the DSM-5 has been replaced by "female sexual interest/arousal disorder" (FSIAD) for women and "male hypoactive sexual desire disorder" for men. [10] The DSM-5 acknowledges that normative variation in sexual desire is wide, particularly in adolescents, and that duration criteria (minimum 6 months) and significant personal distress must both be met before a diagnosis is appropriate.

Why Adolescent Low Desire Is Usually Not HSDD

Sexual desire in adolescence exists on a broad spectrum influenced by hormonal flux during puberty, relationship context, neurodevelopmental stage, and psychosocial factors. The Endocrine Society's clinical practice guidelines on female sexual dysfunction do not include adolescents in the target population for pharmacological intervention. [11] Low sexual desire in a 14-year-old is far more likely to reflect normal developmental variation, depression, anxiety, hormonal contraceptive use, or trauma history than a primary disorder warranting a CNS-active drug.

Preferred Clinical Approach for Adolescents

The appropriate evaluation pathway for an adolescent presenting with sexual desire concerns starts with ruling out treatable causes before any pharmacological consideration. That framework includes:

• Screening for depression and anxiety using validated tools (PHQ-A, GAD-7)
• Reviewing all current medications for desire-suppressing effects, particularly hormonal contraceptives, SSRIs, and antipsychotics
• Thyroid function testing (TSH) and prolactin measurement to exclude endocrine contributors
• Assessment for a history of trauma or sexual abuse, which the American Academy of Child and Adolescent Psychiatry identifies as a common driver of sexual dysfunction in adolescents [12]
• Referral to a licensed sex therapist or adolescent psychologist with appropriate training

Pharmacological treatment for desire-related concerns in this age group is not indicated based on current evidence. Cognitive-behavioral therapy and mindfulness-based sex therapy have demonstrated efficacy for sexual dysfunction in adult women in randomized trials, and extrapolation to adolescents via psychotherapy carries a substantially more favorable safety profile than a CNS-active drug. [13]

Ethical and Consent Considerations for Adolescent Prescribing

Informed Consent and Parental Involvement

Prescribing any controlled or REMS-restricted drug to a minor requires careful attention to state-specific consent laws. Sexual health treatments occupy a complex legal space in many states, where minors may have the right to consent to certain sexual health services without parental involvement. The intersection of that right with a drug requiring REMS enrollment and carrying a black-box warning has not been adjudicated in published case law or professional guidelines.

Duty to Disclose Absence of Evidence

A clinician considering off-label flibanserin in an adolescent would be obligated under informed consent doctrine to disclose that no safety or efficacy data exist for this age group, that the drug carries a black-box warning, that it requires REMS enrollment, and that the FDA has never evaluated the drug in patients under 18. A 2019 analysis in JAMA Internal Medicine found that physicians frequently underestimate how much patients value knowing when a treatment is off-label. [14]

Professional Society Positions

No professional society, including the American College of Obstetricians and Gynecologists (ACOG), the North American Menopause Society (NAMS), the Society for Sex Therapy and Research (SSTAR), or the Endocrine Society, has published guidance supporting flibanserin use in adolescents. ACOG's Committee Opinion on female sexual dysfunction addresses adult women exclusively. [15]

Regulatory Pathway if Research Were to Be Pursued

Any future investigation of flibanserin in adolescents would require an Investigational New Drug (IND) application under 21 CFR Part 312, full IRB approval at each participating institution, pediatric-specific pharmacokinetic sampling as required by FDA's Pediatric Study Decision Tree, and independent data safety monitoring board oversight. [4] The FDA's guidance on pediatric drug development specifies that extrapolation from adults is only permissible when the disease course and drug response are sufficiently similar, and sexual desire neurobiology in adolescents has not been established as comparable to adult premenopausal women in any published model. [4]

Alternatives With More Favorable Evidence Profiles

Psychotherapy

A 2017 Cochrane review (Frühauf et al.) examined psychological interventions for sexual dysfunction in women and found cognitive behavioral therapy produced significant improvements in desire, arousal, and distress across 20 RCTs. [13] While that review focused on adults, the absence of pharmacological risk makes psychotherapy the first-line approach for adolescents by default.

Treating Underlying Conditions

Switching a desire-suppressing antidepressant (for example, from sertraline to bupropion, which showed improved sexual function in a 2002 randomized trial of 234 patients) [16] addresses the root cause rather than layering another CNS-active agent onto an adolescent's treatment regimen. The same logic applies to evaluating and potentially adjusting hormonal contraceptives, which have measurable effects on free testosterone and sexual desire in adolescent girls. [17]

Hormonal Evaluation

A serum free testosterone below the lower limit of normal for the patient's Tanner stage warrants endocrinology referral. Testosterone deficiency secondary to hypopituitarism, premature ovarian insufficiency, or adrenal insufficiency is rare but treatable and should be excluded before any other intervention is considered. [11]

Summary Table: Flibanserin vs. Evidence Standards for Adolescent Use

| Criterion | Adult (Approved) | Adolescent (12 to 17) | |---|---|---| | FDA approval | Yes (premenopausal women) | No | | Key trial data | 2 RCTs, N approximately 2,400 | None | | Pharmacokinetic data | Adult PK characterized | No pediatric PK data | | Safety monitoring program | ADDYI REMS active | REMS not designed for minors | | Professional society guidance | ACOG, NAMS (adult use) | No society endorses use | | Black-box warning applicability | Alcohol interaction documented | Alcohol use prevalent in age group | | First-line recommendation | 100 mg nightly after counseling | Psychotherapy and treat underlying cause |