Addyi (Flibanserin) for Women 65 and Older: What You Need to Know About Transitioning to Adult Care

Why This Article Exists: The Gap Between Approval and Real Life

Flibanserin was approved by the FDA in August 2015 for acquired, generalized HSDD in premenopausal women. The approval came with a Risk Evaluation and Mitigation Strategy (REMS) program, later modified, that centered on the alcohol interaction and hypotension risk.

What the approval did not do was study women over 65 in any meaningful way. The three key trials, BEGONIA, VIOLET, and DAISY, enrolled predominantly women in their 30s and 40s. The oldest subgroup analyses stop well short of the geriatric threshold. That means every clinician prescribing flibanserin to a woman in her late 60s, 70s, or beyond is working from extrapolated data, not direct evidence.

That is not automatically a reason to refuse treatment. Low sexual desire causes real distress. HSDD affects an estimated 8 to 10 percent of women across all age groups, and distress about desire does not disappear at menopause. What it does mean is that both you and your prescribing clinician need to understand exactly where the evidence ends and where clinical judgment begins.

This article maps that boundary clearly.

What Flibanserin Actually Does in the Brain

Flibanserin is not a hormone. It does not raise estrogen, testosterone, or any other sex hormone. It is a multifunctional serotonin receptor agonist and antagonist that acts primarily at 5-HT1A (agonist) and 5-HT2A (antagonist) receptors, with secondary dopamine D4 activity.

The proposed mechanism is a rebalancing of the brain's excitatory and inhibitory sexual signaling. Too much serotonin tone relative to dopamine and norepinephrine is theorized to suppress desire. Flibanserin nudges that ratio back.

How This Differs From Sildenafil (and Why That Matters for Older Women)

Sildenafil works in the genitals. Flibanserin works in the brain. That distinction is relevant for older women because:

1. Genital blood flow issues (common after menopause) are not what flibanserin treats.
2. CNS effects, including sedation, dizziness, and next-day cognitive fog, are the main side effects, and they interact with the polypharmacy burden that many women over 65 carry.
3. The blood-pressure drop that happens when flibanserin meets alcohol is a central nervous system event, not just a vascular one.

Metabolism: CYP3A4 and Why Age Changes the Equation

Flibanserin is metabolized primarily by CYP3A4 and secondarily by CYP2C19. Both enzyme systems show age-related decline. Hepatic blood flow drops by roughly 40 percent between age 25 and 75. Glomerular filtration rate falls as well, though renal clearance is a minor pathway for this drug.

The practical implication: a 68-year-old woman taking 100 mg of flibanserin at bedtime may have meaningfully higher peak plasma concentrations than a 38-year-old at the same dose. Higher exposure means a longer duration of sedation and a greater drop in blood pressure if any CYP3A4 inhibitor, including grapefruit juice, is co-administered.

No geriatric pharmacokinetic study of flibanserin has been published as of this review. That is an evidence gap, and it is a significant one.

Sexual Desire After 65: The Physiology Driving the Question

Sexual desire in women over 65 is shaped by several converging forces that are largely absent in younger women.

Postmenopausal Hormonal Terrain

Estradiol levels in postmenopausal women average less than 20 pg/mL compared to 100 to 400 pg/mL during the follicular phase of the reproductive years. Testosterone, which contributes to desire in women across all ages, declines gradually from the late 20s onward; by the mid-60s, total testosterone is roughly half what it was at peak reproductive years.

Flibanserin was not tested against this hormonal backdrop in any key trial. The BEGONIA, VIOLET, and DAISY trials enrolled premenopausal women with normal ovarian function. Postmenopausal women, including those on hormone therapy, were specifically excluded or underrepresented.

Genitourinary Syndrome of Menopause (GSM)

Many women over 65 have genitourinary syndrome of menopause (GSM), characterized by vaginal dryness, dyspareunia, and reduced arousal. GSM is not what flibanserin treats. Treating GSM first, with local vaginal estrogen or ospemifene, sometimes resolves the desire concern without any central drug being needed at all.

A clinician who jumps to flibanserin without first addressing GSM in an older woman is likely missing the primary diagnosis.

Relationship, Grief, and Psychosocial Factors

Partner loss, caregiver burden, depression, and body-image changes all affect desire after 65. Flibanserin has a modest effect size even in premenopausal women. In women whose low desire is primarily driven by psychosocial context, the drug is unlikely to do meaningful work.

Flibanserin Efficacy: What the Numbers Actually Say

The three key trials showed that flibanserin increased satisfying sexual events (SSEs) by approximately 0.5 to 1.0 additional SSEs per month compared to placebo. Desire scores on the Female Sexual Function Index improved, but the absolute difference was small.

The FDA's own advisory committee noted the modest effect size before approving the drug. The drug was approved because the distress HSDD causes is real and the need for any treatment option justified the modest benefit.

Here is a framework not published elsewhere: when considering flibanserin in a woman over 65, run a simple four-part pre-check before writing the prescription.

The WomanRx Geriatric Flibanserin Pre-Check:

1. GSM ruled out or treated? If not, treat GSM first and reassess in 8 weeks.
2. Depression screened? PHQ-9 score below 10 is a reasonable threshold; untreated depression depresses desire more than flibanserin can lift it.
3. Fall risk assessed? Use the CDC STEADI algorithm. If the patient already has a fall history, flibanserin's hypotension risk may outweigh any sexual benefit.
4. Medication list reviewed for CYP3A4 inhibitors? Diltiazem, fluconazole, clarithromycin, and dozens of other common drugs in older women substantially raise flibanserin exposure.

Only after all four checks are addressed does prescribing make clinical sense.

Safety in Women Over 65: The Risks That Are Amplified

Hypotension and Falls

The prescribing label carries a boxed warning for hypotension and syncope, particularly when flibanserin is combined with alcohol or CYP3A4 inhibitors. In younger women, a brief blood-pressure drop is uncomfortable. In a 70-year-old woman with pre-existing orthostatic hypotension or who takes an ACE inhibitor plus a diuretic, the same drop can mean a fractured hip.

Falls are the leading cause of injury-related death in adults over 65, with approximately 36 million falls occurring annually in the United States. Any drug that lowers blood pressure or causes dizziness deserves extra scrutiny in this population.

Sedation and CNS Overlap

Flibanserin causes somnolence in approximately 11 percent of users at the 100 mg dose. Many women over 65 are already taking a benzodiazepine, sleep aid, antihistamine, or opioid. The additive CNS depression from combining any of these with flibanserin has not been formally studied in older women.

Clinicians should review the complete medication list, including over-the-counter sleep aids containing diphenhydramine, before initiating flibanserin in any woman over 65.

The Alcohol Prohibition

The alcohol interaction with flibanserin is not a mild caution. In the dedicated alcohol interaction study cited in the label, 18 of 25 participants experienced hypotension or syncope when they consumed two standard drinks within two hours of flibanserin.

For older women who drink socially, even moderate amounts, this prohibition is not manageable as "drink less." It means drink nothing, on any day you take flibanserin. Given that flibanserin is taken every night, that is a lifetime prohibition on alcohol for the duration of treatment.

Some women will view this as an acceptable trade. Others will not. That conversation needs to happen explicitly before the prescription is written.

Drug Interactions Disproportionately Common in Older Women

Women over 65 are more likely than men of the same age to be prescribed multiple medications, partly because autoimmune conditions, thyroid disease, and osteoporosis disproportionately affect women and require ongoing treatment. The following drug categories, all common in this age group, are moderate to strong CYP3A4 inhibitors that can substantially raise flibanserin exposure:

• Calcium channel blockers (diltiazem, verapamil)
• Antifungals (fluconazole, itraconazole)
• Macrolide antibiotics (clarithromycin, erythromycin)
• Some antidepressants (fluvoxamine, nefazodone)
• Grapefruit and grapefruit juice

The label states that moderate CYP3A4 inhibitors are contraindicated with flibanserin, and strong inhibitors are absolutely contraindicated. This list of contraindicated combinations is long enough that a thorough medication reconciliation is mandatory before any prescription.

Sex-Specific Pharmacology: What Changes After Menopause

This section contains information that most flibanserin articles skip. The original trials were done exclusively in premenopausal women, so all pharmacokinetic data comes from women with functioning ovaries.

Estrogen influences CYP enzyme expression. CYP3A4 activity decreases modestly after menopause due to lower circulating estradiol, and this is separate from the age-related hepatic decline described earlier. The combined effect means postmenopausal women may metabolize flibanserin more slowly than premenopausal women, increasing both peak concentration and half-life.

If a postmenopausal woman is also on systemic hormone therapy containing estradiol, CYP3A4 activity may be partially restored, making her metabolism profile closer to a premenopausal woman. This interaction has not been directly studied.

The takeaway is not to avoid flibanserin in women on hormone therapy. It is to recognize that the PK profile in a 67-year-old not on HT, a 67-year-old on oral estradiol, and a 40-year-old premenopausal woman are likely different, and we are prescribing to all three groups using data from only the third.

Who This Is Right For, and Who It Is Not

Women Over 65 Who Might Benefit

• Women with documented HSDD (acquired, not lifelong; generalized, not situational) whose distress about low desire is the primary complaint
• Women who have already been evaluated and treated for GSM and depression without resolution of desire concerns
• Women who do not drink alcohol or are willing to stop completely
• Women whose medication list has been reviewed and contains no CYP3A4 inhibitors
• Women with no history of falls, syncope, or clinically significant hypotension
• Women who have a stable primary care relationship for ongoing monitoring

Women Over 65 for Whom Flibanserin Is Likely Not Appropriate

• Women with a fall history or known orthostatic hypotension
• Women taking any moderate or strong CYP3A4 inhibitor that cannot be stopped
• Women whose low desire is primarily related to GSM, partner issues, depression, or grief and has not been addressed
• Women with hepatic impairment (the drug is contraindicated in hepatic impairment)
• Women who are not willing or able to abstain from alcohol

Pregnancy, Lactation, and Contraception

For most women 65 and older, pregnancy is not a consideration. Spontaneous pregnancy after 65 is exceedingly rare. Confirmed postmenopausal status, defined as 12 or more consecutive months of amenorrhea without other cause, means pregnancy is effectively not a risk.

However, women who have entered the geriatric age bracket while still in late perimenopause, which is uncommon but not impossible, should be aware of the following:

Flibanserin has no adequate and well-controlled studies in pregnant women. Animal reproduction studies showed no clear teratogenicity at doses used clinically, but the human data simply does not exist. The drug should not be used during pregnancy.

Lactation data is equally absent. It is not known whether flibanserin passes into human breast milk. Given that most women over 65 are not breastfeeding, this is rarely a clinical issue in this population, but it is stated here for completeness and for the rare perimenopausal 65-year-old who may still be nursing an adopted infant or using a surrogate situation.

Women in perimenopause who are over 60 but not yet confirmed postmenopausal should use effective contraception if they have any possibility of pregnancy and wish to use flibanserin.

The Transition-to-Adult-Care Lens: What This Means for Older Women

"Transition to adult care" in the geriatric context refers to the process of moving older patients from one care model to another: from a specialist (endocrinologist, gynecologist, oncology survivor clinic) back to primary care, or from primary care into a women's-health focused telehealth practice like WomanRx.

For flibanserin specifically, this transition raises several concrete issues:

Medication Reconciliation at Every Care Transition

Flibanserin is a drug where a single overlooked interaction can produce a dangerous outcome. Every time a woman over 65 changes care settings, her complete medication list, including supplements and OTC products, must be reviewed against the flibanserin interaction profile. Diltiazem added by a new cardiologist, or fluconazole prescribed by a dermatologist for a nail infection, can produce toxicity quickly.

Continuity of the Alcohol Counseling

The prohibition on alcohol is easy to establish at the start of treatment and easy to forget two years later when the patient is seeing a new provider. Every care transition should include re-education on the alcohol-flibanserin interaction, not as a lecture, but as a specific clinical check-in.

Reassessment of Benefit Over Time

The Menopause Society recommends periodic reassessment of any treatment for sexual dysfunction to confirm ongoing benefit and acceptable risk. For a woman who started flibanserin at 62 and is now 70, the risk-benefit calculation may have shifted. Falls become more consequential with age. Polypharmacy often increases. A structured annual review is appropriate.

Depression and Cognitive Changes

New-onset depression and early cognitive changes are common in women in their late 60s and 70s. Both can suppress desire independently of any neurochemical deficit that flibanserin addresses. A woman who was a good candidate for flibanserin at 65 may have a different primary diagnosis at 72. Providers inheriting a flibanserin prescription should not assume it still fits.

Monitoring After Initiation

If a woman over 65 does start flibanserin, the following monitoring schedule is reasonable based on the prescribing information and general geriatric prescribing principles:

• Week 2 to 4: Check for dizziness, next-morning sedation, and any falls or near-falls. Ask about blood pressure symptoms on standing.
• Month 2: Reassess desire with a validated tool such as the Female Sexual Distress Scale-Revised (FSDS-R). If no subjective improvement in desire or distress, the drug is unlikely to work for this patient.
• Month 4: Full medication reconciliation. Confirm alcohol abstinence. Review orthostatic blood pressure if the patient reports any dizziness.
• Annually: Formal reassessment of benefit versus fall risk and polypharmacy burden.

The FDA label states that if there is no improvement after 8 weeks, the drug should be discontinued. That 8-week decision point is especially relevant for older women, where every additional month of exposure carries continued fall risk.

Alternatives Worth Discussing First

Before reaching for flibanserin in a woman over 65, the following evidence-based alternatives deserve consideration:

Local vaginal estrogen: If GSM is contributing to avoidance of sex, which reduces desire, local estrogen (cream, ring, or insert) is highly effective, systemically minimal, and carries no CNS or hypotension risk. ACOG supports local vaginal estrogen as safe for most postmenopausal women, including breast cancer survivors in many cases.

Systemic hormone therapy: For women within 10 years of menopause onset who have no contraindications, systemic HT can improve desire as a secondary benefit in some women, particularly those with vasomotor symptoms that disrupt sleep and mood.

Testosterone: Off-label testosterone (cream or gel at female-range doses) has the strongest evidence base for HSDD in postmenopausal women. A 2019 systematic review in The Lancet Diabetes and Endocrinology found testosterone significantly improved desire, arousal, and satisfying sexual events in postmenopausal women. It is not FDA-approved for this indication, but many clinicians consider it the preferred first-line agent in postmenopausal HSDD.

Sex therapy and couples counseling: Particularly when the desire concern is tied to relationship dynamics or grief, psychotherapy has a lasting effect that no drug produces.

A Note on Evidence Equity

Women over 65 were not meaningfully enrolled in the trials that led to flibanserin's approval. That is a data gap that reflects a broader pattern in women's health research: older women, particularly those past menopause, are systematically excluded from trials, then asked to accept prescriptions extrapolated from data on younger women.

The honest clinical statement is this: we do not know whether flibanserin's modest efficacy in premenopausal women translates to postmenopausal women over 65. We do not have geriatric PK data. We do not have fall incidence data from a dedicated geriatric cohort. The risks described in this article are real. The benefit estimate is borrowed from a different population.

That does not mean the drug should never be used in this age group. It means the decision should be made with eyes fully open, with thorough medication review, with fall risk formally assessed, and with a clear 8-week checkpoint to see whether the drug is actually doing anything.

Sexual health matters at every age. Women deserve both treatment options and honest information about their limits.