Background/Objectives: Acyclovir, valacyclovir, and famciclovir are widely used antiviral agents, but comparative data on neuropsychiatric adverse event reporting are limited. This study’s aim was to compare neuropsychiatric adverse event reporting among acyclovir, valacyclovir, and famciclovir and to evaluate the influence of demographic and temporal factors. Methods: A retrospective pharmacovigilance analysis was conducted using the FDA Adverse Event Reporting System (FAERS, Q4 2003–Q3 2025). Unique reports in which acyclovir, valacyclovir, or famciclovir was the primary suspect drug were analyzed. Disproportionality was assessed using the reporting odds ratio (ROR), proportional reporting ratio (PRR), and information component (IC). Between-drug differences in the proportion of neuropsychiatric reports were examined using multivariable logistic regression adjusted for age, sex, region (with Japan as a separate category), and reporting year, together with overlap and inverse probability weighting and sensitivity analyses. A narrow clinical phenotype (encephalopathy/neurotoxicity, altered consciousness/delirium, hallucination/psychosis, and seizure) was the primary outcome, and a broad System Organ Class (SOC)-based definition was a secondary outcome. Results: Of 16,071 unique primary-suspect reports (acyclovir, 6641; valacyclovir, 8980; famciclovir, 450), 4942 (30.8%) contained at least one nervous system or psychiatric Preferred Term (broad definition), and 2471 (15.4%) contained the narrow phenotype. All three drugs showed strong disproportionality signals for encephalopathy-related terms (e.g., toxic encephalopathy ROR 71.63 for acyclovir and 123.39 for valacyclovir; neurotoxicity ROR 55.74 and 48.57, respectively). For the primary narrow phenotype, reporting did not differ between valacyclovir and acyclovir (aOR 1.06, 95% CI 0.96–1.17) and was not higher for famciclovir (aOR 0.72, 95% CI 0.54–0.96; adjusted p = 0.055). Only with the secondary broad definition was the adjusted proportion of neuropsychiatric reports higher for valacyclovir (aOR 1.15, 95% CI 1.07–1.24) and famciclovir (aOR 1.41, 95% CI 1.14–1.75) than for acyclovir. The valacyclovir difference was confined to reports from Japan (aOR 1.88, 95% CI 1.52–2.33) and was absent elsewhere (aOR 1.06, 95% CI 0.98–1.15; interaction p < 0.001), whereas the famciclovir excess reflected non-specific terms such as dizziness and headache. Older age was independently associated with neuropsychiatric reporting (narrow phenotype: aOR 2.52, 95% CI 2.24–2.82). Conclusions: Acyclovir, valacyclovir, and famciclovir share a consistent, encephalopathy-dominated neuropsychiatric reporting signal in FAERS. Apparent between-drug differences depended on the case definition and on reports from Japan and should not be interpreted as differences in neurotoxic risk. Clinical vigilance for encephalopathy is warranted with all three agents, particularly in older patients, while recognizing that FAERS data cannot establish causality or absolute risk.

Background: Human papillomavirus-induced disruption of the anogenital mucosal barrier may increase susceptibility to other sexually transmitted infections (STIs), and guidelines recommend STI screening in patients with anogenital warts (AGW). We aimed to determine the seroprevalence of concomitant STIs in patients with AGW over a five-year period and to perform an exploratory assessment of associated demographic factors. Methods: In this retrospective, cross-sectional study, all consecutive patients clinically diagnosed with AGW between December 2020 and October 2025 (n = 779) were evaluated. Serological results for HBsAg, anti-HBs, anti-HCV, anti-HIV, and syphilis (treponemal and non-treponemal) were obtained. Seroprevalence was estimated with Wilson 95% confidence intervals (CIs) using the number of patients actually tested as the denominator. Patterns of multiple reactive serological markers were described, and the relationship between age and seropositivity was examined using a Cochran–Armitage trend test. Associations of demographic factors with concomitant STI seropositivity were explored using Fisher’s exact test with Woolf logit CIs and a complementary Firth penalized logistic regression; given the small number of events, these analyses were considered exploratory and hypothesis-generating. Results: Among 779 patients (585 [75%] male; mean age, 35.80 ± 12.32 years), the overall seroprevalence of concomitant STIs was 2.4% (19/779; 95% CI, 1.6–3.8). Seroprevalence was 1.4% for HBsAg, 0.9% for anti-HCV, 0.2% for anti-HIV, and 1.6% for treponemal antibodies, while anti-HBs immunity was present in 53.5% of patients. Two patients (10.5% of seropositive cases) had more than one concomitant STI. Seropositivity increased from 0.7% in patients aged 17–24 years to 3.5% in those aged ≥45 years, although the trend was not statistically significant (p = 0.13). Anti-HBs negativity was associated with concomitant STI seropositivity (OR = 5.63; 95% CI, 1.60–19.83; p = 0.003); this association was attenuated and no longer statistically significant after excluding HBV markers (OR = 2.73; 95% CI, 0.70–10.69; p = 0.200). A complete-case analysis restricted to patients with a fully defined testing panel yielded a similar prevalence estimate (2.8%; 95% CI, 1.7–4.5). Conclusions: The seroprevalence of the tested markers in patients with AGW was low but non-negligible and increased with age, while the subgroup of markers more consistent with current infection was less common. Anti-HBs negativity was associated with the composite outcome, but a sensitivity analysis showed this was largely attributable to its expected link with HBV status. These findings support guideline-recommended serological screening—including hepatitis B vaccination assessment—in all patients with AGW, and should be regarded as hypothesis-generating given the limited number of seropositive cases.