Common Antibiotic Doxycycline Linked to Lower Schizophrenia Risk

Research published in the American Journal of Psychiatry indicates that the antibiotic doxycycline may significantly reduce the risk of developing schizophrenia in some young people. The study, conducted by researchers from the University of Edinburgh, in collaboration with the University of Oulu and University College Dublin, analyzed data from over 56,000 adolescents who received mental health services in Finland. The findings suggest that those treated with doxycycline had a 30–35% lower risk of developing schizophrenia compared to peers prescribed other antibiotics.

Schizophrenia is a severe mental disorder that typically emerges in early adulthood, often characterized by hallucinations and delusional beliefs. The researchers aimed to explore preventive measures for this condition, particularly among adolescents who have previously attended mental health services for other issues.

To conduct their analysis, the team employed advanced statistical modeling techniques on large-scale healthcare register data. They discovered that the protective effects of doxycycline were not merely due to the treatment of acne, which is also a common use for the antibiotic. This indicates a more profound relationship between the medication and mental health outcomes.

The potential link between doxycycline’s effectiveness and its impact on inflammation and brain development is particularly noteworthy. Doxycycline is a broad-spectrum antibiotic frequently used to treat various infections, including acne. Previous studies have indicated that it can reduce inflammation in brain cells and influence a process known as synaptic pruning, where the brain refines its neural connections. Excessive synaptic pruning has been associated with the onset of schizophrenia.

Professor Ian Kelleher, the lead author of the study and a Professor of Child and Adolescent Psychiatry at the University of Edinburgh, emphasized the importance of these findings. “As many as half of the people who develop schizophrenia had previously attended child and adolescent mental health services for other mental health problems. At present, though, we don’t have any interventions that are known to reduce the risk of going on to develop schizophrenia in these young people. That makes these findings exciting,” he stated.

While the study presents promising insights, it is essential to note that it is observational in nature, and firm conclusions on causality cannot be drawn without further research. Professor Kelleher stressed the need for additional investigations into the protective effects of doxycycline and other anti-inflammatory treatments in adolescent psychiatric patients as a potential strategy for reducing the risk of severe mental illness in adulthood.

The implications of this research could pave the way for new preventive interventions for schizophrenia, a condition that affects millions globally. As the scientific community continues to explore the links between physical health and mental well-being, these findings represent a significant step forward in understanding and potentially mitigating the risks associated with severe mental disorders.

For further details, refer to the American Journal of Psychiatry (2025). DOI: 10.1176/appi.ajp.20240958.