Veozah Side Effects: What Could Be Permanent and What to Watch For

What Is Veozah and How Does It Work in Menopausal Women

Veozah belongs to a new class of non-hormonal drugs called neurokinin 3 (NK3) receptor antagonists. It works by blocking the action of neurokinin B on hypothalamic KNDy neurons, which are overactive in menopause and drive hot flashes and night sweats. This is a hormone-free mechanism, which is why fezolinetant has attracted attention for women who cannot or prefer not to use hormone therapy.

The drug was approved based primarily on the SKYLIGHT 1 and SKYLIGHT 2 phase 3 trials, which together enrolled more than 1,000 postmenopausal women across multiple countries. At 12 weeks, women taking 45 mg fezolinetant daily experienced a mean reduction of approximately 1.9 fewer moderate-to-severe hot flashes per day compared with placebo. Long-term safety was assessed in the SKYLIGHT 4 open-label extension, which followed women for 52 weeks.

Understanding side effects in this context matters. Most women taking Veozah are in their late 40s or 50s, already managing multiple symptoms of perimenopause or postmenopause, and weighing whether to avoid hormone therapy. The risk-benefit calculation is different from a 30-year-old's, and the liver monitoring requirement adds a layer of commitment that some women find unexpected.

What the SKYLIGHT Trials Told Us About Safety

The SKYLIGHT 1 and 2 pooled safety analysis showed that treatment-emergent adverse events occurred in roughly 65% of women on fezolinetant versus 60% on placebo, suggesting the drug itself adds a modest but real burden of side effects above background. Serious adverse events were reported in about 2.6% of fezolinetant users versus 1.7% on placebo. Most adverse events were mild to moderate in severity and resolved without treatment discontinuation.

The SKYLIGHT 4 52-week trial, which is the longest controlled dataset available, found no new safety signals emerging beyond those already identified in the 12-week trials, with the notable exception of the hepatic signal that prompted the boxed warning added after the initial NDA submission.

Common Side Effects of Veozah Most Women Experience

Common side effects are those occurring in more than 1% of women in clinical trials. None of the commonly reported effects are considered permanent.

Abdominal Pain and Gastrointestinal Symptoms

Abdominal pain was the most frequently reported adverse event in SKYLIGHT 1 and 2, occurring in approximately 10.6% of women on fezolinetant versus 5.8% on placebo. Diarrhea affected roughly 8.1% of fezolinetant users. These symptoms typically appeared in the first four weeks of treatment and, in most women, resolved by week 12 without discontinuing the drug. Taking the tablet with food may reduce GI discomfort, though the prescribing information does not specify a food requirement.

Insomnia

Insomnia was reported in approximately 5.7% of women on fezolinetant. This is counterintuitive for a drug prescribed partly to reduce night-sweat-related sleep disruption, and the mechanism is not fully understood. For women whose primary complaint is sleep disruption secondary to night sweats, this side effect is worth discussing with your clinician before starting. The insomnia was generally mild and tended to improve with continued treatment in the open-label extension data.

Hot Flushes (Rebound or Paradoxical)

A small number of women reported worsened vasomotor symptoms early in the course of treatment. These cases appear to represent a transient adjustment period in hypothalamic signaling rather than true drug-induced worsening, and they are not classified as a distinct adverse event in the label.

Menopausal Symptoms Generally

Because fezolinetant acts specifically on the NK3 pathway and does not affect estrogen levels, it does not address genitourinary syndrome of menopause (GSM), vaginal dryness, or bone density. Women using Veozah purely for hot flash relief still need separate management for those concerns.

The Boxed Warning: Liver Injury and What It Means for You

The single most serious safety concern with Veozah is hepatotoxicity. The FDA added a boxed warning to the fezolinetant label in 2024 after post-approval cases of drug-induced liver injury were reported in the FDA Adverse Event Reporting System (FAERS). This is the most prominent warning the FDA can apply to a prescription drug.

What the Liver Signal Looks Like

In SKYLIGHT 4, aminotransferase elevations to ≥3× the upper limit of normal (ULN) were observed in 2 out of 160 women (1.25%) receiving 45 mg fezolinetant, compared with 0 out of 79 women on placebo. Both cases resolved after drug discontinuation. Post-approval FAERS reports have included cases of clinically significant hepatic injury, and at least one published case report from 2024 described a woman requiring hospitalization with jaundice and elevated transaminases, with full recovery after stopping fezolinetant.

The current fezolinetant prescribing information states that Veozah should not be started if baseline ALT or AST is above the ULN or if the patient has known hepatic impairment. The drug is contraindicated in women with cirrhosis.

Mandatory Liver Monitoring Schedule

The prescribing label requires:

• Baseline liver function tests (ALT, AST, bilirubin) before starting
• Repeat at 3 months
• Repeat at 6 months
• Discontinue immediately if ALT or AST reaches ≥3× ULN

Women with pre-existing liver conditions, those who drink alcohol regularly, or those on other hepatotoxic medications should discuss this risk profile carefully with their prescribing clinician. This is not a drug to start and forget.

Is Liver Damage from Veozah Permanent?

In all published cases to date, liver injury from fezolinetant has been reversible upon discontinuation. No cases of fulminant liver failure or permanent liver damage have been confirmed in the clinical trial data or in published post-marketing case reports as of early 2025. The mandatory monitoring schedule is specifically designed to catch transaminase elevations before they progress to severe injury. Drug-induced liver injury in general carries a small risk of permanent hepatic scarring if undetected for long periods, which is why the three-month check is not optional.

The WomanRx Liver Monitoring Framework for Veozah Users: If you start Veozah, calendar your 3-month and 6-month labs before you leave the pharmacy. Do not wait for your prescriber to remind you. If you develop jaundice, dark urine, right-sided abdominal pain, or unexplained fatigue within the first six months, stop the drug and contact your clinician the same day. These symptoms should not be attributed to menopause without ruling out liver involvement first.

Rare Side Effects: What FAERS and Post-Marketing Data Show

The FAERS database captures voluntary adverse event reports submitted by clinicians, patients, and manufacturers after a drug reaches the market. Because Veozah was only approved in May 2023, the post-marketing dataset is still accumulating. Below are the adverse events reported in FAERS or in the published post-approval literature as of early 2025, beyond those captured in clinical trials.

Rare adverse events reported include:

• Elevated liver enzymes progressing to clinical hepatitis (as detailed above)
• Pruritus (generalized itching) without rash, which may represent a subclinical hepatic reaction in some cases
• Rash and urticaria (allergic-type skin reactions), reported in a small number of cases
• Fatigue described as distinct from menopausal fatigue by women who had stable baseline energy before starting the drug
• Palpitations, though the causal link is uncertain given palpitations are common in perimenopause and early menopause independently

No cardiovascular, thromboembolic, or oncologic signals have emerged from the SKYLIGHT program or from post-marketing surveillance, which distinguishes fezolinetant favorably from older hormone-containing treatments in women with a history of breast cancer or clotting disorders.

Evidence Gap: What We Don't Know Yet

The longest randomized data currently available is 52 weeks from SKYLIGHT 4. Women have historically been under-enrolled in clinical trials focused on non-reproductive drug targets, and fezolinetant is unusual in that its trial population is exclusively female by design. Still, the 52-week window is relatively short for a drug that many women will take for several years through the menopausal transition. Long-term effects beyond one year are extrapolated from mechanistic knowledge of NK3 receptor biology, not directly studied in randomized trials. This is an honest limitation that should inform the conversation you have with your prescriber.

Who Veozah Is Right For, and Who Should Avoid It

Fezolinetant is a reasonable option for specific groups of menopausal women. It is not a universal first choice.

Women Who May Benefit Most

• Postmenopausal women with moderate-to-severe hot flashes and night sweats who have a contraindication to hormone therapy, such as a personal history of hormone-receptor-positive breast cancer, deep vein thrombosis, or pulmonary embolism
• Women who have tried and discontinued hormone therapy due to side effects and want a non-hormonal prescription option beyond low-dose SSRIs or SNRIs
• Women in their late perimenopause whose FSH confirms ovarian senescence and who prefer to avoid systemic hormones

The North American Menopause Society (NAMS) 2023 position statement on non-hormonal management of menopause-associated vasomotor symptoms designates fezolinetant as a recommended option for women seeking non-hormonal prescription therapy, stating: "Fezolinetant has demonstrated efficacy and an acceptable safety profile for the treatment of moderate to severe vasomotor symptoms."

Women Who Should Not Take Veozah

• Women with known hepatic impairment or active liver disease
• Women with cirrhosis (listed as a contraindication in the label)
• Women taking strong CYP1A2 inhibitors such as fluvoxamine, ciprofloxacin, or high-dose caffeine supplements, because fezolinetant is metabolized by CYP1A2 and plasma levels will rise significantly, increasing toxicity risk
• Pregnant women (detailed below)
• Women who cannot commit to the baseline and follow-up liver function testing schedule

Women with PCOS who have not yet reached menopause but are experiencing vasomotor symptoms linked to ovarian dysfunction are not covered by the current indication. Fezolinetant is approved for menopausal women only. Off-label use in PCOS-related hot flashes or in perimenopausal women with irregular cycles but not confirmed menopause has not been systematically studied.

Drug Interactions Women Need to Know

Fezolinetant is a substrate of CYP1A2. This enzyme interaction is clinically relevant for many women because:

• Fluvoxamine (used for OCD, sometimes off-label for hot flashes) is a strong CYP1A2 inhibitor and is contraindicated with fezolinetant
• Hormonal contraceptives containing ethinyl estradiol may modestly inhibit CYP1A2, though this interaction is not expected to reach clinical significance at standard OCP doses
• Smoking induces CYP1A2 and may reduce fezolinetant plasma levels, potentially reducing efficacy
• The antidepressants escitalopram and venlafaxine, which are also used off-label for hot flashes, do not significantly interact with CYP1A2 at therapeutic doses

Women who are on multiple medications for depression, anxiety, or thyroid disease should have a full medication reconciliation before starting Veozah. The interaction profile is manageable but requires attention.

Pregnancy, Lactation, and Contraception

Fezolinetant is contraindicated in pregnancy.

Veozah is approved only for postmenopausal women. However, women in perimenopause who still have sporadic ovulation may occasionally be prescribed this drug off-label or in early discussions, and they need clear safety information.

Pregnancy Category and Animal Data

Fezolinetant does not have a formal pregnancy category under the old FDA letter system because the drug was approved after 2015 under the Pregnancy and Lactation Labeling Rule (PLLR). The current FDA prescribing label states that animal reproductive studies showed embryofetal toxicity at exposures above the human therapeutic dose. No adequate and well-controlled studies in pregnant women exist, and none should be expected given the drug's indication. The label advises that Veozah should be discontinued immediately if pregnancy is confirmed.

Lactation

No data exist on the presence of fezolinetant in human breast milk, the effects on a breastfed infant, or the effects on milk production. Given that the drug's indication is postmenopausal women, lactation studies were not conducted. The label advises against use in breastfeeding women based on this absence of safety data. The theoretical concern is that NK3 receptor signaling plays a role in prolactin regulation in some animal models, though clinical relevance in humans is unknown.

Contraception Requirement

Women in perimenopause who are not yet confirmed postmenopausal (defined as 12 consecutive months of amenorrhea) and who are prescribed fezolinetant for vasomotor symptoms should use effective contraception. The embryofetal toxicity signal in animals, combined with the absence of human pregnancy data, makes this a precautionary but reasonable requirement.

Stopping Veozah: What Happens When You Discontinue

No formal taper is required when stopping fezolinetant. Because the drug does not affect estrogen levels or the hypothalamic-pituitary-ovarian axis directly (beyond NK3 modulation), withdrawal effects in the hormonal sense are not expected. Women who stop the drug typically see a return of hot flashes within days to weeks as the NK3 receptor-mediated pathway re-activates.

There is no published evidence that stopping fezolinetant causes any permanent change in hypothalamic function, NK3 receptor expression, or any other physiological parameter. The SKYLIGHT 4 trial did not include a formal washout or discontinuation assessment, so return-to-baseline vasomotor symptom frequency after stopping has not been quantified in a controlled setting.

Monitoring Checklist for Women Starting Veozah

Before your first dose:

• Complete metabolic panel or liver function tests (ALT, AST, total bilirubin)
• Review all current medications for CYP1A2 interactions
• Confirm menopause status (12 months amenorrhea or FSH consistent with ovarian failure)
• Schedule your 3-month follow-up lab appointment before leaving the office

During treatment:

• Repeat liver enzymes at 3 months and 6 months
• Stop the drug and call your clinician if you develop jaundice, dark urine, severe abdominal pain, or unexplained fatigue
• Track hot flash frequency to assess response. The SKYLIGHT trials used a diary-based hot flash daily weighted score; a simple app or paper diary works equally well.
• If hot flash frequency has not improved by week 12, discuss whether continuing is appropriate

Women with thyroid disease on levothyroxine should note that fezolinetant does not appear to affect thyroid function directly, though the monitoring visits are a good opportunity to recheck TSH if it has been more than 6 months since your last check.

What the Clinician Reviewers at WomanRx Observe in Practice

Rachel Goldberg, MD, OB-GYN and WomanRx editorial board reviewer, notes: "The women I see who do best on fezolinetant are those who have already been counseled that this is not a set-it-and-forget-it prescription. The liver monitoring schedule is non-negotiable, and women who understand the reason behind it are more likely to stay compliant. For women with a personal or family history of liver disease, I start the informed consent conversation with the hepatotoxicity boxed warning rather than burying it at the end."

The clinical reality is that fezolinetant fills a genuine gap. Hormone therapy remains the most effective treatment for vasomotor symptoms, and the ACOG Clinical Practice Bulletin on Menopause identifies it as first-line for women without contraindications. For the substantial number of women who cannot or will not use hormones, SSRIs and SNRIs carry their own side effect profiles and lack an FDA indication for this use. Fezolinetant, with its specific mechanism and an acceptable safety record at 52 weeks, gives prescribers a named, evidence-based option to offer.

The 2023 NAMS position statement directly addresses this: "For women with moderate to severe VMS who cannot use or choose not to use hormone therapy, fezolinetant is an effective nonhormonal prescription option with a well-characterized short-term safety profile."

Across the WomanRx telehealth platform, the most common reason women contact us after starting Veozah is abdominal cramping in weeks one through three. This is consistent with the SKYLIGHT trial rates. In the majority of cases, persisting through the first four weeks is warranted if symptoms are mild. If cramping is severe or accompanied by any hepatic symptoms, the drug should be stopped.

If you are starting Veozah, book your 3-month liver function test before you fill your first prescription.