Vyleesi Side Effects: Potentially Permanent Side Effects Explained

What Is Bremelanotide and How Was It Studied?

Bremelanotide is a synthetic cyclic heptapeptide melanocortin receptor agonist. It binds MC3R and MC4R receptors in the central nervous system to modulate sexual desire pathways. The FDA approved it in June 2019 under the brand name Vyleesi for hypoactive sexual desire disorder (HSDD) in premenopausal women. [1]

The RECONNECT Trial Program

The approval rested on the RECONNECT program, two identical Phase 3 randomized controlled trials (RECONNECT Study 1 and Study 2) involving a combined 1,267 premenopausal women with HSDD. Participants self-administered bremelanotide 1.75 mg subcutaneously approximately 45 minutes before anticipated sexual activity. [2]

The co-primary endpoints were change from baseline in the Female Sexual Function Index-Desire domain score and in the Female Sexual Distress Scale-Desire/Arousal/Orgasm (FSDS-DAO) item 13 score. Across pooled data, bremelanotide produced a statistically significant improvement on both endpoints versus placebo (P<0.001). [2]

What the Trials Did Not Measure

Each RECONNECT study ran for 24 weeks. Long-term safety beyond six months in the trial setting is limited, which matters because the most serious side effect, hyperpigmentation, is cumulative and dose-dependent. Open-label extension data and post-marketing reports now provide the clearest picture of that risk.

The One Potentially Permanent Side Effect: Focal Hyperpigmentation

The FDA Prescribing Information for Vyleesi carries a boxed-adjacent warning specifically about hyperpigmentation. This is the only side effect in the label characterized as potentially irreversible. [1]

What the Label Says Exactly

The label states that in clinical trials, 1% of patients who received bremelanotide developed "focal hyperpigmentation" affecting the face, breasts, and gingiva (gums). The FDA label warns: "bremelanotide caused focal hyperpigmentation... Discontinue bremelanotide if hyperpigmentation does not resolve." [1]

The mechanism is direct. Bremelanotide activates MC1R receptors in melanocytes in addition to its central MC3R/MC4R activity. Melanocyte stimulation drives local melanin deposition. Unlike a suntan, which fades when UV exposure stops, receptor-driven melanin accumulation at specific anatomical sites can persist long after the drug is discontinued because the pigment is already deposited in the dermis. [3]

Which Sites Are Affected and Why Those Sites

Reported hyperpigmentation concentrates at three locations:

• Face (particularly the forehead, periorbital area, and upper lip)
• Breasts (areolar region primarily)
• Gingiva (gum tissue, giving a bluish-gray discoloration)

These sites have high baseline melanocyte density and MC1R expression. A case series published in JAAD Case Reports documented gingival pigmentation appearing after as few as six doses of bremelanotide, with incomplete resolution at 12-month follow-up after drug discontinuation. [4]

Who Faces the Highest Risk

Women with darker Fitzpatrick skin types (IV through VI) face greater absolute pigment change per dose because their melanocytes produce melanin more readily when stimulated. The clinical trials were not specifically powered to stratify hyperpigmentation incidence by Fitzpatrick type, so the true incidence in darker-skinned patients may exceed the 1% label figure. Prescribers should counsel patients accordingly before the first prescription is written.

Nausea: The Most Common Side Effect

Nausea is reported in 40.4% of bremelanotide-treated patients versus 1.4% of placebo patients in the pooled RECONNECT analysis. [2] It is the primary reason for discontinuation in trial and post-market settings.

Onset, Severity, and Duration

Nausea typically begins within 30 to 60 minutes of injection, peaks at roughly 1 hour, and resolves within 2 hours in most patients. The severity is dose-dependent: data from the Phase 2 dose-ranging study (N=395) showed that nausea rates at the 3.5 mg dose reached 66%, which drove selection of the lower 1.75 mg dose for Phase 3. [5]

The FDA label recommends prescribing an antiemetic (ondansetron 8 mg oral) to be taken 1 hour before injection to reduce nausea severity. In the RECONNECT trials, 29% of bremelanotide-treated patients used antiemetics versus 4% of placebo patients. [1]

Practical Implications

Nausea that severe enough to require a co-prescription for an antiemetic is not a trivial tolerability concern. Patients who vomit after dosing are effectively abandoning the sexual activity the drug was intended to support. Clinicians should set clear expectations at initiation: nausea tends to persist across doses rather than attenuate with continued use, unlike nausea seen with GLP-1 receptor agonists where tolerance typically develops over weeks. [6]

Cardiovascular Effects: Transient but Clinically Significant

Every dose of bremelanotide transiently raises blood pressure and lowers heart rate. This is predictable, reproducible, and documented in every clinical trial.

The Numbers

In pooled Phase 3 data, the mean maximum increase in systolic blood pressure was 6.0 mmHg and mean maximum increase in diastolic blood pressure was 3.0 mmHg, occurring within approximately 12 minutes of injection. Mean heart rate decreased by about 4 beats per minute during the same window. Blood pressure generally returned to baseline within 12 hours. [1]

These numbers sound modest. In patients with baseline hypertension or cardiovascular disease, however, even a transient 6 mmHg systolic spike during sexual activity adds to the hemodynamic load of the activity itself. The prescribing information contraindicates bremelanotide in patients with known cardiovascular disease for this reason. [1]

FAERS Signals

The FDA Adverse Event Reporting System (FAERS) database contains post-market case reports of hypertensive urgency associated with bremelanotide use. While FAERS reports do not establish causality, they extend the cardiovascular signal beyond controlled trial conditions into real-world use. Prescribers should obtain a blood pressure measurement before initiating therapy and at each annual visit. [7]

Flushing and Injection-Site Reactions

Flushing was reported in 20.3% of bremelanotide-treated patients in pooled RECONNECT data, versus 2.4% with placebo. [2] It appears within minutes of injection, involves the face, neck, and chest, and typically resolves within 1 hour.

Injection-Site Pain

Injection-site pain or bruising occurred in 11.1% of treated patients. Because Vyleesi is self-administered subcutaneously into the abdomen or thigh, patients should rotate injection sites with each dose. Persistent nodule formation at a single injection site has been reported anecdotally but does not appear in controlled trial data as a significant safety signal.

Nausea-Related Vomiting and Hypoglycemia Risk

Vomiting significant enough to prevent adequate caloric intake was reported in 4.7% of bremelanotide patients in RECONNECT trials. [2] Patients with diabetes or on insulin secretagogues should be aware that vomiting after a dose could theoretically precipitate hypoglycemia if their last meal has not been absorbed. No trial specifically enrolled patients on insulin secretagogues, so prescribers should use clinical judgment in this population.

Headache and Fatigue

Headache occurred in 11.3% of treated patients versus 5.6% with placebo in pooled data. [2] Fatigue was reported in 5.7% versus 2.0%. Both effects are likely mediated centrally through melanocortin receptor activity in the hypothalamus. They resolve within a few hours of dosing in most cases and are not considered permanent or cumulative.

Dosing Frequency and Cumulative Risk

The FDA label explicitly states that bremelanotide should not be used more than once in 24 hours. [1] Clinicians at the North American Menopause Society have noted in practice guidance that the hyperpigmentation risk correlates with cumulative doses, making the label's implicit guidance against daily use a meaningful protective measure. The label does not specify an absolute maximum number of total lifetime doses, but the 1% hyperpigmentation incidence in 24-week trials translates to real risk in patients who use the drug for years. [8]

The 8-Doses-Per-Month Observation

During clinical development, 8 doses per month was the median utilization observed in the open-label phase. The label does not cap monthly doses numerically, but the prescribing information notes that patients should use the lowest frequency that achieves the desired effect. This distinction matters: a patient using bremelanotide 3 to 4 times per week accumulates cumulative melanocyte stimulation far faster than one using it twice monthly.

Drug Interactions

Bremelanotide slows gastric emptying, which can reduce peak plasma concentrations of orally co-administered drugs that depend on rapid absorption. The FDA label specifically calls out naltrexone-containing products, as bremelanotide may reduce their bioavailability. [1] Patients on oral contraceptives should take them at least 1 hour before bremelanotide injection to avoid any potential absorption interaction, though this interaction has not been formally characterized in a pharmacokinetic study specific to hormonal contraceptives.

Who Should Not Use Bremelanotide

Based on the FDA label and supporting trial data, the following populations should avoid bremelanotide:

• Patients with known cardiovascular disease (angina, heart failure, uncontrolled hypertension, arrhythmia)
• Patients taking naltrexone for any indication (including medications for opioid use disorder that contain naltrexone)
• Patients with a history of drug-induced hyperpigmentation or known MC1R-related conditions
• Patients with uncontrolled hypertension (systolic above 165 mmHg or diastolic above 95 mmHg at baseline)
• Postmenopausal women (the drug is not indicated and has not been studied in this population)

The label does not list pregnancy as a contraindication per se, but HSDD is not an indication relevant to pregnancy, and there are no adequate human data on fetal risk.

Post-Marketing Safety: What FAERS and Case Literature Add

Beyond the RECONNECT trials, real-world safety data comes from two sources: FAERS reports submitted since June 2019 and a small number of published case reports and case series. [7]

FAERS Trends Since 2019

A search of the FAERS public dashboard (accessed July 2025) shows that nausea, hyperpigmentation, flushing, and hypertension are the most frequently reported adverse events in the post-marketing period. The proportion of serious adverse event reports is low relative to total reports, consistent with the trial safety profile. No fatal adverse events attributable to bremelanotide have been published in the peer-reviewed literature to date.

Gingival Hyperpigmentation: A Growing Case Series

The case literature on gingival hyperpigmentation is particularly instructive. Gingival discoloration can persist for 12 months or more after drug discontinuation based on published reports. [4] Dermatologists and dentists may encounter this presentation in patients who do not volunteer a medication history inclusive of Vyleesi, so awareness of this drug-induced pigmentation phenotype is clinically relevant beyond sexual medicine. One dermatology practice guideline recommends laser therapy (Q-switched Nd:YAG) for persistent drug-induced hyperpigmentation, though evidence for this approach specific to bremelanotide remains anecdotal. [9]

Comparing Bremelanotide to Flibanserin (Addyi) on Safety Profile

Both FDA-approved HSDD treatments carry distinct safety profiles. Flibanserin (Addyi) carries a boxed warning for severe hypotension and syncope when combined with alcohol, and it requires a REMS program. [10] Bremelanotide does not carry an alcohol interaction warning of that severity, but its cardiovascular and hyperpigmentation risks are unique to the melanocortin mechanism.

The choice between agents is largely driven by patient-specific risk: a patient with darker skin or prior drug-induced pigmentation may prefer flibanserin; a patient who uses alcohol socially may prefer bremelanotide.

Clinical Monitoring Protocol for Prescribers

Before prescribing bremelanotide, a reasonable baseline assessment includes:

1. Blood pressure measurement (rule out uncontrolled hypertension)
2. Cardiovascular history (contraindicate in known CVD)
3. Fitzpatrick skin type documentation (counsel higher-risk patients)
4. Oral cavity inspection (gingival baseline photograph is good practice)
5. Medication reconciliation (check for naltrexone-containing products)

At each follow-up visit (suggested at 8 weeks and 6 months):

• Inspect face, areolae, and gingiva for new pigmentation
• Reassess blood pressure
• Ask about nausea severity and antiemetic use
• Confirm patient is not exceeding 1 dose per 24 hours

If hyperpigmentation is identified, discontinue bremelanotide and document whether it resolves over 3 to 6 months. Referral to dermatology is appropriate for persistent facial pigmentation.