Can I Take Quercetin With Addyi (Flibanserin)?

What Is Addyi and Who Is It Approved For?

Flibanserin, sold as Addyi, is the only FDA-approved non-hormonal medication for hypoactive sexual desire disorder (HSDD) in premenopausal women. The FDA approved it in August 2015 after two earlier rejections prompted advocacy from the Even the Score campaign. It is not approved for postmenopausal women or for any male population, and it is explicitly labeled for premenopausal use only.

HSDD is characterized by persistently low sexual desire that causes personal distress, unrelated to another medical condition or medication effect. Estimates from the PRESIDE study suggest roughly 8.9% of U.S. Women aged 18 to 44 meet criteria for HSDD with associated distress, making it one of the more common forms of female sexual dysfunction.

How Flibanserin Works

Flibanserin is not a hormone and is not a phosphodiesterase inhibitor. It acts centrally as a serotonin 1A receptor agonist and serotonin 2A receptor antagonist, with additional weak dopamine D4 agonist activity. The net effect is thought to shift the neurochemical balance in the prefrontal cortex away from serotonin-driven sexual inhibition and toward dopamine/norepinephrine-driven sexual motivation. This mechanism is entirely different from sildenafil (Viagra), which works peripherally on blood flow.

The Approved Dose and Timing

The standard dose is 100 mg taken orally once daily at bedtime. Bedtime dosing is mandatory because daytime dosing dramatically increases the risk of hypotension and syncope. If you have not seen an effect after 8 weeks of consistent use, the FDA label recommends stopping.

What Is Quercetin and Why Do Women Take It?

Quercetin is a flavonoid found naturally in onions, apples, capers, and green tea. As a supplement, it is widely marketed for immune support, anti-inflammatory effects, allergy symptom relief, and cardiovascular health. Some women also take it for PCOS-related inflammation, endometriosis symptom management, or general antioxidant support, although the clinical evidence for these specific female uses remains preliminary.

A 2021 review in Nutrients found that quercetin supplementation doses used in human trials range from 150 mg to 1,000 mg per day, with most immune-focused protocols clustering around 500 to 1,000 mg daily. These are the doses most likely to produce a clinically meaningful drug interaction.

Quercetin as a CYP3A4 Inhibitor

Here is the core pharmacokinetic concern: quercetin inhibits cytochrome P450 3A4 (CYP3A4), the liver enzyme responsible for metabolizing a large fraction of orally taken drugs, including flibanserin. In vitro studies have consistently demonstrated quercetin's inhibitory activity at CYP3A4, CYP2C9, and CYP2C19, with the CYP3A4 effect being the most clinically relevant for drug interactions.

When CYP3A4 is inhibited, drugs that depend on it for clearance accumulate to higher plasma concentrations than intended. For flibanserin, this is not a theoretical concern.

The Interaction: What Happens When You Take Both

Flibanserin's CYP3A4 Dependence

Flibanserin is extensively metabolized by CYP3A4. The FDA prescribing information includes a boxed warning against combining flibanserin with moderate or strong CYP3A4 inhibitors because such combinations can increase flibanserin exposure by several fold. The label specifically lists fluconazole (a moderate CYP3A4 inhibitor) as capable of increasing flibanserin AUC by approximately 7-fold, with a corresponding rise in maximum concentration.

Quercetin is not on the FDA's named inhibitor list because it was not studied in the flibanserin approval trials. But the mechanism is the same pathway. The degree of inhibition depends on quercetin dose, formulation (aglycone vs. Glycoside), and your individual CYP3A4 baseline activity.

What "Higher Flibanserin Levels" Actually Means for You

The adverse effects of flibanserin are dose-dependent. At therapeutic concentrations, the most common side effects are dizziness, somnolence, nausea, and fatigue. In the pooled Phase 3 DAISY and BEGONIA trials, dizziness occurred in approximately 11% of women on flibanserin 100 mg versus 2% on placebo. Hypotension and syncope occurred in roughly 0.4% of flibanserin-only users, but this rate climbed substantially when CYP3A4 inhibitors or alcohol were co-administered.

If quercetin raises your flibanserin exposure meaningfully, you are effectively taking a higher functional dose. That raises your probability of sitting up and feeling the room spin, or standing up and fainting.

Is This a Pharmacodynamic Interaction Too?

There is a secondary consideration beyond enzyme inhibition. Quercetin has mild antihistamine activity, documented in in vitro and animal models as a mast cell stabilizer and histamine release inhibitor. Antihistamines can cause central nervous system sedation. Flibanserin itself is sedating at bedtime doses. Combining two centrally sedating agents could theoretically add to somnolence beyond what the CYP3A4 interaction alone predicts.

This pharmacodynamic component is less well-characterized in human data than the enzyme inhibition piece. The evidence in women specifically is thin, and the sedation overlap is extrapolated from the known CNS profiles of each agent rather than from a direct combination study.

A practical way to think about this interaction: quercetin affects flibanserin through two separate channels: it slows clearance (pharmacokinetic) and it may add sedative effect (pharmacodynamic). Even if the pharmacodynamic component is small, the pharmacokinetic component alone warrants caution.

Does the Amount of Quercetin Matter?

Yes, substantially. Dietary quercetin from food, perhaps 5 to 40 mg per day from a typical Western diet, is unlikely to produce meaningful CYP3A4 inhibition. A clinical pharmacokinetic study published in the European Journal of Clinical Pharmacology found that oral quercetin at 500 mg twice daily for 14 days significantly increased the AUC of the CYP3A4 substrate felodipine by 36%, a real but not catastrophic increase.

At 1,000 mg per day, which is the upper range of many immune-support and PCOS protocols, the inhibitory effect grows. No human study has directly measured the quercetin-flibanserin combination. That evidence gap is real, and your prescriber cannot give you a precise "safe dose" of quercetin to take alongside Addyi because that number does not exist in the published literature yet.

What the existing pharmacokinetic data suggest:

• Dietary quercetin from food: probably not clinically significant
• Quercetin supplements at 250 mg/day or less: low but not zero risk
• Quercetin supplements at 500 mg/day: moderate concern, clinical judgment needed
• Quercetin supplements at 1,000 mg/day or more: meaningful inhibition likely, avoid combination

This is a framework based on available CYP3A4 inhibition data extrapolated to flibanserin's metabolism, not a formally studied dose-response. Treat these ranges as guides, not guarantees.

Life-Stage Considerations: Who Is Most Affected

Premenopausal Women (Reproductive Years)

Addyi is only approved for premenopausal women, so this is the core population. Your CYP3A4 activity fluctuates mildly across the menstrual cycle, with some evidence that estrogen influences CYP3A4 expression, potentially altering drug clearance differently in the follicular versus luteal phase. This means your flibanserin exposure may vary slightly across your cycle even without quercetin, and adding a CYP3A4 inhibitor on top of that variability adds another unpredictable layer.

Women With PCOS

PCOS is one of the more common reasons women in reproductive years reach for quercetin, given its anti-inflammatory and insulin-sensitizing properties studied in small randomized trials like a 2017 RCT in the Journal of the Endocrine Society showing quercetin improved hormonal markers in women with PCOS. If you have PCOS and your provider has you on quercetin for that purpose, and you are also being treated for HSDD with flibanserin, this exact combination is one your prescriber and pharmacist both need to know about explicitly.

Perimenopause and Postmenopause

Flibanserin is not FDA-approved for perimenopausal or postmenopausal women. If you are in perimenopause, low libido may stem from fluctuating estrogen and progesterone, and hormone therapy or ospemifene for GSM may be more appropriate options before reaching for an off-label flibanserin prescription. The Menopause Society's 2022 position statement on sexual health in menopause does not list flibanserin as a recommended therapy for postmenopausal HSDD. Off-label use in perimenopausal women does occur clinically, but the trial data supporting it in this group are sparse.

Trying to Conceive

If you are trying to conceive or planning pregnancy in the near future, flibanserin should be stopped before you begin trying. See the pregnancy section below.

Pregnancy, Lactation, and Contraception

Flibanserin is contraindicated in pregnancy. This is not a relative contraindication or a "use with caution" situation. The FDA label carries no assigned pregnancy category under the old lettering system, but animal reproductive toxicity studies showed fetal harm at doses producing exposures comparable to human therapeutic exposure. The prescribing information states that flibanserin should be discontinued before pregnancy, and no adequate human pregnancy safety data exist.

Practical requirement: Because flibanserin is approved only for premenopausal women, many of whom are in their fertile years, you must use reliable contraception while taking it if you have any chance of becoming pregnant. A method with <1% typical-use failure rate (IUD, implant, or consistent combined hormonal method) is appropriate given the lack of human safety data.

Lactation: There are no data on flibanserin transfer into human breast milk. The drug's lipophilic properties suggest it likely transfers, but quantitative data in nursing women do not exist. Because the indication is sexual desire disorder (not a life-threatening condition) and because infant exposure cannot be estimated, most clinicians advise against use while breastfeeding. If you are postpartum and experiencing low libido, addressing postpartum hormonal changes, sleep deprivation, and thyroid function first is more evidence-based than starting flibanserin.

Quercetin in pregnancy and lactation: Quercetin crosses the placenta and accumulates in fetal tissue in animal studies. A 2010 review in Reproductive Toxicology flagged high-dose quercetin supplementation as potentially genotoxic at the fetal level in animal models, though human data are absent. Dietary quercetin is considered safe in pregnancy; high-dose supplementation should be avoided.

Who This Is Right For, and Who Should Reconsider

Addyi May Be Appropriate If You Are

• A premenopausal woman with a confirmed HSDD diagnosis (distress-linked low desire not explained by another cause)
• Not pregnant, not breastfeeding, and using reliable contraception
• Free of hepatic impairment (flibanserin is contraindicated in any degree of hepatic impairment)
• Willing to abstain from alcohol entirely while taking the drug
• Not currently on moderate or strong CYP3A4 inhibitors, including azole antifungals, certain antibiotics, or grapefruit juice in large amounts

Reconsider If You Are

• Postmenopausal or in confirmed menopause (not the approved population; alternatives exist)
• Taking quercetin at 500 mg or more per day for another condition
• On fluconazole, ketoconazole, clarithromycin, or other known CYP3A4 inhibitors
• A regular alcohol drinker who is not willing to stop (the alcohol-flibanserin hypotension risk is substantial and real)
• Pregnant, trying to conceive within the next few months, or breastfeeding

What to Do If You Are Already Taking Both

Do not stop either medication abruptly without talking to your prescriber first. Stopping flibanserin has no known withdrawal syndrome, but you want a supervised plan. Here is what a reasonable clinical conversation covers:

1. Report both to your prescriber and pharmacist at the same visit. Many pharmacists are not routinely asked about quercetin; bring the bottle with the dose listed.
2. Discuss whether quercetin is necessary. If you are taking it for general antioxidant support, the evidence base for that indication is thin, and stopping it eliminates the interaction risk entirely.
3. If quercetin is medically justified (your provider has you on it specifically for PCOS inflammation or another condition), ask whether the dose can be reduced to <250 mg/day or whether an alternative supplement with less CYP3A4 activity could serve the same purpose.
4. Monitor for interaction signs. These include unusual dizziness within 2 to 4 hours of your bedtime dose, feeling faint when standing, or daytime sedation beyond what you experienced in your first weeks on Addyi.
5. Do not rely on dose separation. There is no published evidence that taking quercetin in the morning and flibanserin at bedtime eliminates the interaction. Quercetin's CYP3A4 inhibition can persist beyond its own plasma half-life depending on the form and dose you take.

The Broader Picture: Supplement Interactions With Addyi Women Should Know

Flibanserin has several documented and suspected supplement/food interactions beyond quercetin. Clinicians reviewing women on Addyi should screen for all of these:

| Supplement or Food | Interaction Type | Direction | Risk Level | |---|---|---|---| | Grapefruit juice | CYP3A4 inhibition | Raises flibanserin levels | High: avoid | | St. John's Wort | CYP3A4 induction | Lowers flibanserin levels | Moderate: reduces efficacy | | Quercetin | CYP3A4 inhibition | Raises flibanserin levels | Moderate: caution | | Kava | CNS sedation (additive) | Increases somnolence | Moderate: caution | | Valerian | CNS sedation (additive) | Increases somnolence | Low-moderate | | Melatonin | CNS sedation (additive) | Increases somnolence | Low: bedtime overlap |

This table is a clinical summary based on known pharmacological properties and does not imply direct human trial evidence for each combination with flibanserin specifically. The grapefruit and St. John's Wort interactions are best characterized; the others are extrapolated from mechanism.

Evidence Gaps: What We Do Not Know Yet

Direct human pharmacokinetic studies of quercetin combined with flibanserin do not exist in the published literature as of this writing. What we have is:

• Flibanserin's CYP3A4 metabolism, well-characterized in its FDA submission data
• Quercetin's CYP3A4 inhibitory activity, demonstrated in vitro and in at least one human felodipine interaction study
• No human study measuring flibanserin plasma levels with co-administered quercetin

Women have historically been under-represented in pharmacokinetic drug-supplement interaction trials, and this is a striking example of that gap. Flibanserin is approved exclusively for women, and quercetin is disproportionately used by women for conditions like PCOS and endometriosis-related inflammation, yet the combination has never been formally studied in any human trial. The clinical guidance above is the best available extrapolation from existing data, and your prescriber's individualized judgment remains essential.

Talking to Your Prescriber: Specific Questions to Bring

Dr. Elena Vasquez, MD, WomanRx clinical reviewer, offers this direct framing for the conversation: "When a woman on Addyi asks about quercetin, I want to know three things: the dose she is taking, the reason she is taking it, and whether there is a clinical alternative with less CYP3A4 activity. If she is taking 500 mg or more daily for a documented condition, I will not clear the combination without a monitoring plan. If she is taking it for general wellness with no specific indication, stopping the supplement is the simpler path."

Specific questions to ask your prescriber at your next visit:

• "I take [dose] mg of quercetin for [reason]. Does that create a clinically meaningful interaction with my flibanserin dose?"
• "Is there a quercetin dose threshold below which you would feel comfortable with me continuing both?"
• "Should I check a blood pressure log after starting or stopping quercetin to catch any change in flibanserin effect?"
• "Is there a supplement with similar benefits for my condition that has lower CYP3A4 inhibitory activity?"