Introduction Data are emerging showing the adverse consequences on mental health of the general public due to the COVID-19 pandemic. Little is known about the needs of veterans with pre-existing mental health difficulties during the COVID-19 pandemic.

Methods Data were collected through a cross-sectional online survey from a randomly selected sample (n=1092) of military veterans who have sought help for mental health difficulties from a veteran-specific UK-based charity. The response rate was 25.2% (n=275). Participants were asked to complete a range of standardised mental health outcomes (post-traumatic stress disorder (PTSD): Post-traumatic Stress Disorder Checklist, common mental health difficulties (CMDs): 12-Item General Health Questionnaire, difficulties with anger: 5-Item Dimensions of Anger Reactions—Revised and alcohol misuse: Alcohol Use Disorders Identification Test) and endorse a list of potential stressors related to changes to daily life resulting from COVID-19. Regression analyses were fitted to explore predictors of mental health severity.

Results It was observed that symptoms of common mental disorder and PTSD (69.3% and 65.0%, respectively) were the most commonly reported to have been exacerbated by the pandemic. Lack of social support and reporting increasing numbers of stressors related to COVID-19 were consistently associated with increasing severity of a range of mental health difficulties.

Conclusions Our findings suggest veterans who had pre-existing mental health difficulties prior to the outbreak of COVID-19 may be at increased risk of experiencing CMDs as a result of the pandemic. Intervening to improve levels of social support and offering practical guidance to better manage any additional stressors relating to the pandemic may provide strategies to help reduce the burden of mental health symptoms.