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Flibanserin (Addyi) — 5-HT1A agonist / 5-HT2A antagonist for hypoactive sexual desire disorder
A daily bedtime prescription drug for acquired, generalised hypoactive sexual desire disorder (HSDD), on its current US label in women under 65 regardless of menopausal status (extended in December 2025) — the first FDA-approved treatment for the condition, and one of the most contested. It is not an on-demand pill and not a 'female Viagra': it must be taken every night for weeks, and pooled analyses put the average benefit at roughly half an additional satisfying sexual event per month over placebo. Its defining risk is severe hypotension and syncope, which alcohol and CYP3A4 inhibitors amplify. It carries a US FDA boxed warning and, under the US label, is contraindicated with moderate/strong CYP3A4 inhibitors and in any degree of hepatic impairment.
Prescription medication — not a dietary supplement
Flibanserin is a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
Flibanserin doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from medium-quality meta-analyses and randomised trials published 2010–2026 with a typical study size of 949 participants.
Based on 13 studies · 2 meta-analyses · 7 RCTs · 19,215 total participants
Confidence
High confidenceBy outcome
The randomised evidence base is large and genuinely high-quality in design — four 24-week phase-3 placebo-controlled trials (DAISY, VIOLET, BEGONIA, SNOWDROP) plus a randomised-withdrawal trial — but the effect it establishes is very small. The 2016 JAMA Internal Medicine meta-analysis (5,914 women) pooled a mean difference of 0.49 additional satisfying sexual events per month, found women's global impression of improvement corresponded to 'minimal improvement to no change', and graded the overall quality of evidence as very low; a 2024 meta-analysis of 7,906 women reproduced a similarly small 0.69-event difference and concluded the benefit may be overshadowed by adverse events. Co-primary eDiary desire endpoints failed in two of the three premenopausal pivotal trials. Add a US FDA boxed warning for hypotension and syncope, US-label contraindications with moderate/strong CYP3A4 inhibitors and any hepatic impairment, and 4-fold increases in dizziness and somnolence, and the risk-benefit is narrow. Scored as Emerging: the trials are good, the drug's effect is marginal.
1 trial ongoing or recruiting · 12 completed on ClinicalTrials.gov
9 of the completed trials have posted results
Registered trials show research momentum for Flibanserin, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Oct 2026
Flibanserin (Addyi) is a centrally acting serotonergic drug — a postsynaptic 5-HT1A agonist and 5-HT2A antagonist — that was originally developed as an antidepressant, failed at that, and was repurposed for hypoactive sexual desire disorder (HSDD). In August 2015 the FDA approved it for acquired, generalised HSDD in premenopausal women, making it the first approved pharmacotherapy for the condition. The US ADDYI label covers women under 65 with acquired, generalised hypoactive sexual desire disorder that causes marked distress or interpersonal difficulty and is not explained by a coexisting medical or psychiatric condition, relationship problems, or a medicine or other drug. The indication was extended in December 2025 regardless of menopausal status. Getting there took three attempts: Baksh and colleagues, reviewing the decision in Drug Safety, describe 'two prior failed FDA reviews' and note that the eventual approval followed 'extensive advocacy and politicization surrounding the product's relevance to women and sexual health', over what they call a 'tenuous risk/benefit profile'. That contested history is the honest frame for the evidence.
What the trials show. Four large manufacturer-sponsored 24-week phase-3 randomised trials — DAISY, VIOLET and BEGONIA in premenopausal women, and SNOWDROP in naturally postmenopausal women — consistently beat placebo on satisfying sexual events (SSEs), the FSFI desire domain and the Female Sexual Distress Scale. But the margins are small and the placebo response is large: in BEGONIA the SSE gain was 2.5 versus 1.5 events; in SNOWDROP, 1.0 versus 0.6. The co-primary electronic-diary desire score failed to separate from placebo in both DAISY (no group significant) and VIOLET (P = 0.07 for the 100 mg arm). The 2016 JAMA Internal Medicine systematic review and meta-analysis by Jaspers et al. — the key critical appraisal — pooled five published and three unpublished trials in 5,914 women and found a mean difference of 0.49 additional SSEs per month (95% CI 0.32–0.67) for 100 mg versus placebo, alongside sharply elevated risks of dizziness (RR 4.00), somnolence (RR 3.97), nausea (RR 2.35) and fatigue (RR 1.64), and more than double the rate of discontinuation for adverse events (RR 2.19). Women's own global impression scores 'indicated minimal improvement to no change', and the authors graded the overall quality of evidence as very low. A 2024 meta-analysis of eight RCTs in 7,906 women reproduced the picture — a slightly larger SSE difference of 0.69 per month — and concluded that flibanserin's 'therapeutic advantages may be overshadowed by the higher likelihood of adverse events'.
How it must be taken, and the misconception worth correcting. Flibanserin is 100 mg taken once daily at bedtime, every night — not before sex. Bedtime dosing exists specifically to move the sedation, hypotension and syncope risk out of waking hours. Benefit builds over weeks; prescribing guidance is to stop at 8 weeks if there has been no improvement. Nothing about it works acutely, and there is no evidence supporting on-demand use.
The alcohol problem. Severe hypotension and syncope, amplified by alcohol, drove a US FDA boxed warning and an initial outright alcohol contraindication under a restrictive Risk Evaluation and Mitigation Strategy. Two manufacturer-sponsored crossover studies in healthy premenopausal women then failed to reproduce an additive alcohol effect: dosing 100 mg at steady state 2, 4 or 6 hours after 0.4 g/kg ethanol produced no significant excess of hypotension, orthostatic hypotension or syncope versus placebo, and a single-dose study across 0.2–0.6 g/kg ethanol found no clear alcohol dose-response for dizziness — though both used daytime dosing, which the authors flag as inconsistent with the drug's bedtime indication, and the higher ethanol doses left more participants whose standing blood pressure could not be obtained. On that basis the FDA narrowed the restriction in 2019 and replaced the certification-based REMS with a medication-guide-only REMS. The current US label no longer forbids alcohol outright but still includes it in the boxed warning: wait at least two hours after one or two standard drinks before taking the bedtime dose, skip the dose entirely if three or more drinks were consumed that evening, and do not drink again until the following day. Two contraindications did not soften — moderate or strong CYP3A4 inhibitors, and any degree of hepatic impairment, both because they raise flibanserin exposure and with it the risk of syncope and hypotension.
The bottom line. Flibanserin is a real drug with real randomised evidence and a real, if small, effect on a genuinely distressing condition for which the alternatives are thin. It is also a drug whose average benefit is about half an extra satisfying sexual event a month, whose most common experience is dizziness or sleepiness, and whose safety profile requires daily attention to alcohol, liver function and a long list of interacting medicines. It is a prescription medicine, not a supplement, and its US label covers only women under 65 who meet the narrow HSDD criteria.
Flibanserin is characterised across its phase-3 trial programme as a postsynaptic serotonin-1A receptor agonist and serotonin-2A receptor antagonist. It was originally developed as an antidepressant and repurposed for hypoactive sexual desire disorder after failing in depression.
In a microdialysis study in female rats, acute flibanserin decreased serotonin and increased norepinephrine in the medial prefrontal cortex, nucleus accumbens and medial preoptic area, and increased dopamine in the medial prefrontal cortex and medial preoptic area (but not the nucleus accumbens). Repeated dosing raised basal dopamine and norepinephrine in the prefrontal cortex. Glutamate and GABA were unchanged. The authors propose this stimulatory-versus-inhibitory rebalancing as the mechanistic underpinning of the drug's effect.
Flibanserin is 100 mg once daily at bedtime. Bedtime administration is deliberate: it minimises the risk of hypotension, syncope, accidental injury and CNS depression during waking hours. Benefit accrues over weeks of continuous dosing — the pivotal trials measured change over 24 weeks — and there is no evidence for taking it before sexual activity.
CYP3A4 is the primary enzyme metabolising flibanserin, with a contribution from CYP2C19. Drugs that inhibit CYP3A4 raise exposure and with it the risk of severe hypotension and syncope, which is why moderate and strong CYP3A4 inhibitors are contraindicated. CYP2C19 poor metabolisers (roughly 2–5% of Caucasians and Africans, 2–15% of Asians per the FDA label) also have higher exposure, though the label offers no alternative dosing for them.
How Flibanserin works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
The central safety conversation. Wait at least two hours after one or two standard drinks before taking the bedtime dose; skip the dose entirely if three or more drinks were consumed that evening; do not drink again until the following day. The original outright alcohol contraindication was narrowed by the FDA in 2019 after crossover studies found no additive effect, but the boxed warning remains.
Contraindicated at any degree of hepatic impairment — liver dysfunction significantly raises flibanserin concentrations and the risk of serious adverse effects.
Since December 2025 the US label covers women under 65 regardless of menopausal status, with the same narrow HSDD criteria and every other restriction on the label. The SNOWDROP trial in naturally postmenopausal women showed statistically significant improvements versus placebo (1.0 vs 0.6 satisfying sexual events, FSFI desire 0.7 vs 0.4). The label says it is not indicated in geriatric patients, where safety and effectiveness have not been established.
Review the full medication list with a prescriber before starting. Moderate and strong CYP3A4 inhibitors are contraindicated, and combining with serotonergic antidepressants or other CNS depressants compounds sedation.
Higher flibanserin exposure and potentially greater risk of hypotension, syncope and CNS depression per the FDA label, which nonetheless provides no alternative dosing. Roughly 2–5% of Caucasians and Africans and 2–15% of Asians are poor metabolisers.
These are Limitations of Use on the label rather than contraindications: not indicated in men or to enhance sexual performance, and the indication covers only women under 65 (the label says it is not indicated in pediatric or geriatric patients). The label's actual contraindications are moderate/strong CYP3A4 inhibitors, any degree of hepatic impairment, and hypersensitivity. Not indicated when low desire is attributable to a co-existing medical or psychiatric condition, relationship problems, or the effect of a medication or drug
The defining safety issue and the subject of the US FDA boxed warning. Alcohol increases the risk of severe hypotension and syncope. Alcohol was initially contraindicated outright; after two crossover studies in healthy premenopausal women failed to demonstrate an additive effect, the FDA narrowed the restriction in 2019. Current labelling: wait at least two hours after one or two standard drinks before the bedtime dose, skip the dose entirely after three or more drinks that evening, and do not drink again until the following day.
Contraindicated. CYP3A4 is the primary enzyme metabolising flibanserin; inhibiting it raises exposure and with it the risk of severe hypotension and syncope.
Flibanserin is contraindicated in any degree of hepatic impairment because liver dysfunction significantly increases drug concentrations.
Flibanserin itself causes CNS depression, somnolence and sedation — the reason it is dosed at bedtime. Combining it with other CNS-depressant medicines compounds that effect. Reviewers of the approval identified numerous drug-drug interactions, alongside alcohol, as the exposures that potentiate dizziness, hypotension and syncope, and recommended heightened post-market vigilance.
CYP2C19 also contributes to flibanserin metabolism; poor metabolisers have higher exposure and, per the FDA label, potentially increased risk of hypotension, syncope and CNS depression. The label provides no alternative dosing for them.
Tip: Risk ratio 4.00 (95% CI 2.56–6.27) versus placebo in meta-analysis; 10.5% incidence in DAISY. Take at bedtime, avoid alcohol per the label, and rise slowly.
Tip: Risk ratio 3.97 (95% CI 3.01–5.24) versus placebo; 11.8% in DAISY. Bedtime dosing exists specifically to move this out of waking hours; do not drive if sedated the next morning.
Tip: Risk ratio 2.35 (95% CI 1.85–2.98) versus placebo in meta-analysis; among the most frequently reported adverse events in BEGONIA and SNOWDROP.
Tip: Risk ratio 1.64 (95% CI 1.27–2.13) versus placebo; 10.3% in DAISY.
Tip: The US FDA boxed-warning risk. Amplified by alcohol, by moderate/strong CYP3A4 inhibitors, and by hepatic impairment. Seek care for fainting; review all concomitant medicines with a prescriber before starting.
Tip: Both are listed in the FDA labelling among adverse effects occurring at greater than 2% incidence, below dizziness, somnolence, nausea and fatigue. Insomnia was also raised versus placebo in the 2024 meta-analysis.
Tip: Risk ratio 2.19 (95% CI 1.50–3.20) versus placebo; 9.6% versus 3.7% in BEGONIA. If side effects are intolerable, discuss stopping — no withdrawal reactions were observed on discontinuation in the randomised-withdrawal trial.
Flibanserin has an evidence score of 4.5/10 — emerging evidence based on 13 indexed studies, including 2 meta-analyses. A daily bedtime prescription drug for acquired, generalised hypoactive sexual desire disorder (HSDD), on its current US label in women under 65 regardless of menopausal status (extended in December 2025) — the first FDA-approved treatment for the condition, and one of the most contested. It is not an on-demand pill and not a 'female Viagra': it must be taken every night for weeks, and pooled analyses put the average benefit at roughly half an additional satisfying sexual event per month over placebo. Its defining risk is severe hypotension and syncope, which alcohol and CYP3A4 inhibitors amplify. It carries a US FDA boxed warning and, under the US label, is contraindicated with moderate/strong CYP3A4 inhibitors and in any degree of hepatic impairment. Representative study: PMID 26927498.
The commonly studied dose of Flibanserin is 100 mg once daily at bedtime — every night, not before sexual activity. Prescription only. Discontinue at 8 weeks if there has been no improvement in symptoms. Individual needs vary, so check the right dose for you with a healthcare provider.
The best time to take Flibanserin is before bed. It can be taken on an empty stomach. Bedtime dosing is a safety requirement, not a preference: it shifts the risk of hypotension, syncope, accidental injury and CNS depression out of waking hours.
Flibanserin should be used with caution — talk to a healthcare provider before taking it. The most commonly reported side effects are dizziness, somnolence / sedation, nausea. Use caution if any of these apply to you: Concomitant use of moderate or strong CYP3A4 inhibitors (e.g. many antibiotics, antivirals, cardiac drugs, and grapefruit juice) — increases flibanserin exposure and the risk of severe hypotension and syncope; Any degree of hepatic impairment — significantly increases flibanserin concentrations and the risk of serious adverse effects; Known hypersensitivity to flibanserin.
Lactoferrin
Too few graded studiesA multifunctional iron-binding glycoprotein from milk with broad antimicrobial, anti-inflammatory, and immune-modulating properties.
Raloxifene (Evista)
Too few graded studiesA second-generation selective estrogen receptor modulator (SERM) approved for postmenopausal osteoporosis and for reducing the risk of invasive breast cancer in high-risk and osteoporotic postmenopausal women. In the pivotal MORE trial it cut vertebral-fracture risk and reduced invasive (largely ER-positive) breast cancer by ~70%; CORE extended the breast-cancer benefit to 8 years, and the STAR trial showed it roughly matched tamoxifen for invasive-breast-cancer prevention with less uterine cancer. It is used OFF-LABEL by some men for gynecomastia (a small pediatric series found it shrank pubertal breast tissue). The honest limits are non-negotiable: the RUTH trial found NO reduction in coronary events but a significant increase in FATAL STROKE and venous thromboembolism, raloxifene does NOT reduce hip or non-vertebral fractures, and it commonly causes hot flushes and leg cramps. It is NOT a supplement and NOT a longevity drug.
Letrozole
Too few graded studiesA potent non-steroidal aromatase inhibitor (Femara) that blocks estrogen synthesis. Approved for hormone-receptor-positive breast cancer, it is also the evidence-backed first-line drug for ovulation induction in PCOS — where a landmark NEJM RCT showed it BEAT clomiphene on live births. Used off-label in men to raise testosterone and lower estradiol, but that estrogen suppression harms bone and lipids, and in growing boys it carries a vertebral-deformity signal. A prescription drug, not a supplement, and NOT a longevity drug.
Progesterone
Too few graded studiesThe endogenous steroid hormone, sold as a prescription bioidentical (micronized) drug (Prometrium / Utrogestan). It is the ENDOMETRIAL-PROTECTION half of menopausal hormone therapy (it opposes estrogen, and in the PEPI trial prevented estrogen-driven endometrial hyperplasia), and is used for luteal support in IVF and to treat secondary amenorrhea. Oral micronized progesterone is also widely used OFF-LABEL for menopausal SLEEP and hot flashes, because a metabolite (allopregnanolone) is GABA-active and sedating. Randomized trials support these specific indications; in early-pregnancy bleeding the large PRISM trial found no significant increase in live births. It is NOT a general healthy-population enhancer, and the breast-cancer signal from older synthetic progestins (WHI) should not be assumed for micronized progesterone, where data suggest it is more breast- and metabolically neutral but longer-term evidence is limited. Prescription-only and NOT a dietary supplement; OTC 'progesterone creams' absorb erratically and are not equivalent.
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Reviewed by Dr. Baher Al Hakim · Last reviewed July 2026 · evidence from 13 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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