French data highlight a subtle but significant threat to long-term control.
Antibiotics may be quietly undermining the long-term effectiveness of biologic therapies for psoriasis, according to a major French cohort study.
The researchers found that patients exposed to antibiotics were significantly more likely to discontinue their biologic, especially those receiving repeated courses.
The findings, drawn from more than 36,000 real-world treatment initiations, point to a measurable and dose-dependent impact that dermatologists may need to factor into everyday prescribing decisions.
Results have been published this month as a brief report in JAMA Dermatology.
“Clinically, these findings underscore the importance of careful antibiotic prescribing in patients receiving biologics,” the researchers wrote.
“While causality is unproven, minimising unnecessary antibiotic exposure may support better treatment persistence.
“Further research is warranted to confirm these associations, clarify underlying mechanisms, and identify patient-related and treatment-related factors influencing biologic durability.”
The study, conducted between 2011 and 2022, followed 36,129 adults initiating a biologic for psoriasis.
Just over a quarter had been exposed to antibiotics at baseline, while more than 60% received at least one antibiotic course during follow-up. The most frequently used classes were β-lactams, macrolides, and fluoroquinolones.
Using a weighted marginal structural model to account for time-varying exposure and confounding, investigators found that one antibiotic dispensation in the prior six months increased the risk of biologic discontinuation (HR 1.12; 95% CI 1.08–1.16), while two or more courses increased the risk further (HR 1.29; 95% CI 1.24–1.35).
Subgroup analyses were consistent across most biologic classes and reinforced the dose-response pattern.
The researchers noted that altered gut microbial composition – already implicated in psoriasis and systemic immune regulation – may be one mechanism through which antibiotics impair biologic durability.
Immune modulation, infection-related interruptions, or antidrug antibody formation may also contribute.
However, they cautioned that antibiotic exposure may simply be a marker of poorer health or more complex disease, and causality cannot be assumed.
Related
Factors such as female sex, obesity, hypertension, diabetes, alcohol use, respiratory disease, and PPI use after biologic initiation were also associated with reduced persistence.
Despite these uncertainties, the findings raised practical considerations for clinicians managing patients on biologics, the researchers said.
With persistence already known to fall to around 40% at three years, unnecessary antibiotic use may add avoidable pressure to treatment durability.
The authors highlighted strengths including national coverage, a large sample size, and rigorous time-updated analysis, but acknowledged limitations such as lack of data on reasons for discontinuation, adherence, lifestyle factors, and potential residual confounding.
They said their study added weight to ongoing efforts to optimise antibiotic prescribing.
While further mechanistic and prospective studies were needed, the data suggest that careful management of infection risk and prudent antibiotic use may form part of a broader strategy to support long-term biologic success in psoriasis, they wrote.
