A new study has found that a widely used antibiotic could lower the risk of developing schizophrenia in young people.
Researchers discovered that adolescents who were prescribed the antibiotic doxycycline were significantly less likely to later develop schizophrenia than those who received other types of antibiotics.
The finding raises the exciting possibility that an inexpensive and commonly available drug could one day help prevent severe mental illnesses.
Schizophrenia is a serious brain disorder that affects how a person thinks, feels, and behaves. It often begins in early adulthood and can cause hallucinations, delusions, and disorganized thinking.
Because the condition develops gradually, scientists have long been searching for ways to identify people at risk early and find ways to prevent the illness before symptoms appear.
Researchers from the University of Edinburgh, working with scientists from the University of Oulu in Finland and University College Dublin in Ireland, looked for possible links between antibiotic use and schizophrenia.
They analyzed health data from more than 56,000 adolescents in Finland who had received antibiotics while being treated for mental health problems. By using advanced statistical methods, the team compared outcomes between those who had taken doxycycline and those who had taken other antibiotics.
The results were striking. Young people who received doxycycline had a 30 to 35 percent lower risk of developing schizophrenia later in life. This protective effect remained even after the researchers took into account other factors, such as the reason for taking antibiotics or other health conditions.
The study also showed that the reduced risk could not simply be explained by participants being treated for acne, which is a common use for doxycycline among teenagers.
Doxycycline is a broad-spectrum antibiotic often used to treat bacterial infections and skin conditions. But beyond fighting bacteria, it also has anti-inflammatory properties and can influence how brain cells communicate.
Previous research suggests that inflammation in the brain may contribute to psychiatric conditions, including schizophrenia. Doxycycline may help protect brain function by reducing this inflammation and influencing a natural process called synaptic pruning.
This process helps shape the developing brain by removing unnecessary connections, but when it goes too far, it can contribute to brain changes linked to schizophrenia.
Professor Ian Kelleher, a child and adolescent psychiatrist at the University of Edinburgh and lead author of the study, said the findings offer hope for early intervention.
“As many as half of the people who develop schizophrenia had already attended mental health services as teenagers for other problems,” he said. “At the moment, there are no proven treatments that can reduce their risk. That’s why this study is so exciting—it gives us a new direction to explore.”
He added, however, that more research is needed. Because this study was observational, it cannot prove that doxycycline directly prevents schizophrenia.
“We need clinical trials to confirm whether doxycycline truly has a protective effect and to understand how it works,” Kelleher explained. “But this is a strong signal that anti-inflammatory treatments might play a role in preventing severe mental illness.”
The study, published in the American Journal of Psychiatry, involved collaboration between the University of Edinburgh, University of Oulu, University College Dublin, and the St John of God Hospitaller Services Group. It was funded by the Health Research Board.
This research offers a fresh perspective on how we might prevent schizophrenia by addressing inflammation and brain development in young people. If future trials confirm these findings, doxycycline could become one of the first medications used to reduce the risk of this complex mental illness.
The idea that an ordinary antibiotic could protect the brain represents an exciting step toward a new era of prevention-focused mental health care.
If you care about depression, please read studies that vegetarian diet may increase your depression risk, and Vitamin D could help reduce depression symptoms.
For more information about health, please see recent studies that ultra-processed foods may make you feel depressed, and these antioxidants could help reduce the risk of dementia.
The study is published in American Journal of Psychiatry.
Copyright © 2025 Knowridge Science Report. All rights reserved.
