Common Acne Drug Linked to Lower Schizophrenia Risk
Teens treated with doxycycline were 30% less likely to develop schizophrenia later in life.
Could an acne pill cut schizophrenia risk by 30%?
Researchers from the University of Edinburgh, the University of Oulu and University College Dublin, analyzed health records and found that adolescents treated with doxycycline were significantly less likely to go on to develop schizophrenia later in life.
Schizophrenia risk and prevention
Schizophrenia is a severe, chronic mental disorder that typically emerges in early adulthood. The condition affects ~23 million people worldwide.
“Although the peak incidence of psychotic disorders does not occur until after age 20, a high proportion of individuals at risk of psychosis attend child and adolescent psychiatric services earlier in life, typically many years before their psychosis diagnosis,” said the authors of the latest study.
Despite decades of research, no intervention has been shown to reliably reduce the risk of schizophrenia in at-risk young people. The lack of approved preventive strategies remains a major challenge in psychiatry, especially since the window of adolescence, when neural circuits are still maturing, represents one of the few moments when risk might be altered.
During adolescence, the brain undergoes synaptic pruning, eliminating unused connections and refining circuits. Evidence suggests that in people who later develop schizophrenia, this pruning is excessive and may be driven by inflammation or overactive immune-linked pathways.
Doxycycline is a broad-spectrum antibiotic used for infections and acne; however, it can also cross into the brain where it shows anti-inflammatory and neuroprotective properties. Laboratory studies of doxycycline report reduced microglial activity and preserved synapses. Current human studies investigating doxycycline have focused on the treatment of established psychosis, which has generated mixed or inconclusive results. No large-scale observational study has evaluated whether adolescent exposure to doxycycline could reduce the future risk of schizophrenia.
“If we could identify preventive interventions, there would be important opportunities for psychosis prevention within adolescent psychiatric services,” the authors added.
Doxycycline in adolescence and schizophrenia incidence
The research team analyzed whether doxycycline might lower the risk of schizophrenia later in life using Finnish nationwide health registers. They followed all individuals born in Finland between 1987 and 1997 who had attended adolescent psychiatric services between the ages of 13–18 years and had been prescribed antibiotics, generating a cohort of 52,786 young people. Participants were tracked until they were around 30 years of age.
Those who had received doxycycline were compared with peers who had taken other antibiotics. Individuals with a previous diagnosis of psychosis or who had taken isotretinoin (a drug sometimes linked with mental-health side effects) were excluded to reduce bias.
Doxycycline exposure was grouped by total amount prescribed: low (<1,499 mg), medium (1,500–2,999 mg) and high (≥3,000 mg). Using advanced statistical modeling, the researchers adjusted for factors such as sex, birth year, parental education and initial mental-health diagnosis.
“As many as half of the people who develop schizophrenia had previously attended child and adolescent mental health services for other mental health problems,” said corresponding author Dr. Ian Kellehe, a professor of child and adolescent psychiatry at the University of Edinburgh.
In total, ~29% of the participants had been prescribed doxycycline.
After 10 years, 2.1% of those treated with other antibiotics developed schizophrenia, vs 1.4–1.5% in doxycycline users – a reduction of ~30–35%.
The pattern held for adolescents who had required inpatient psychiatric care, a group at a higher baseline risk. The association, however, did not extend to broader “non-affective psychosis” diagnoses, suggesting the effect was specific to schizophrenia.
Checks against possible confounding factors, such as acne treatment or infection severity, did not explain the difference.
Next steps for schizophrenia prevention
The finding aligns with research linking neuroinflammation and abnormal synaptic pruning to schizophrenia, suggesting that modifying inflammatory processes early in life could help protect the brain. Since doxycycline is already widely prescribed and well understood, it presents a realistic starting point for exploring preventive strategies in psychiatry.
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“That makes these findings exciting,” said Kelleher.
However, the research has its limits.
“Because the study was observational in nature and not a randomized controlled trial, it means we can’t draw firm conclusions on causality,” said Kelleher.
The registry data also only records prescriptions, not whether patients took the medication, and it does not capture infection type or severity.
Further studies should investigate how doxycycline might influence brain inflammation and microglial activity.
While preliminary, this work offers an important signal that a simple antibiotic could one day contribute to preventing schizophrenia.
“This is an important signal to further investigate the protective effect of doxycycline and other anti-inflammatory treatments in adolescent psychiatry patients as a way to potentially reduce the risk of developing severe mental illness in adulthood,” concluded Kelleher.
Reference: Lång U, Metsälä J, Ramsay H, et al. Doxycycline use in adolescent psychiatric patients and risk of schizophrenia: an emulated target trial. Am J Psychiatry. 2025. doi: 10.1176/appi.ajp.20240958
This article is a rework of a press release issued by the University of Edinburgh. Material has been edited for length and content.
