A widely used antibiotic could help reduce the risk of schizophrenia, according to a new study. Researchers found that teenagers who took doxycycline were 30–35% less likely to develop schizophrenia in adulthood than those who used other antibiotics.
The findings, published in the American Journal of Psychiatry, were described as “tentative but exciting.”
A Surprising Link Between Antibiotics and Mental Health
The study analyzed data from 56,000 Finnish teenagers, including 16,000 who had been prescribed doxycycline for infections or acne. While the research was not a randomized trial, it revealed a strong connection between the antibiotic and lower schizophrenia risk.
Why Doxycycline Might Help
Experts believe doxycycline may protect the brain by reducing inflammation and supporting healthy synaptic pruning — a natural process where the brain removes unneeded connections during adolescence.
Abnormal pruning has been linked to schizophrenia.
“This study is an important signal to explore the protective effects of doxycycline and other anti-inflammatory treatments,” said Professor Ian Kelleher of the University of Edinburgh.
“If proven, it could help prevent severe mental illness in adulthood.”
Schizophrenia: A Global Challenge
Schizophrenia affects about 23 million people worldwide. It often appears in early adulthood and causes hallucinations, delusions, and disorganized thinking. Treatments can control symptoms, but there is no cure.
This makes prevention a major goal for researchers.
Experts Advise Caution
Other scientists have welcomed the study but warned against jumping to conclusions.
“Many treatments look promising at first but fail in large-scale trials,” said Dominic Oliver, a psychiatry researcher at the University of Oxford.
Dr. Katharina Schmack, from the Francis Crick Institute, agreed. She said that although the results are significant, the effect is modest.
“Instead of five out of 100 people developing schizophrenia, about two to three might after doxycycline treatment,” she explained.
What Comes Next
Researchers say more studies are needed to confirm whether doxycycline truly prevents schizophrenia. If proven, it could open the door to new ways of protecting brain health using existing medicines.
“These findings are important,” Dr. Schmack added. “They help guide biological research that could change how we understand and treat mental illness.”
For now, doxycycline offers a hopeful clue — that an everyday antibiotic might one day help prevent one of the most challenging psychiatric conditions.