OBJECTIVE To determine whether positive expiratory pressure (PEP) by PEP flute self-care is effective in reducing respiratory symptoms among community dwelling adults with SARS-CoV-2 infection and early stage covid-19. DESIGN Non-drug, open label, randomised controlled trial. SETTING Capital Region and Region Zealand in Denmark from 6 October 2020 to 26 February 2021. PARTICIPANTS Community dwelling adults, able to perform self-care, with a new SARS-CoV-2 infection (verified by reverse transcription polymerase chain reaction tests) and symptoms of covid-19. INTERVENTION Participants were randomised to use PEP flute self-care in addition to usual care or have usual care only. Randomisation was based on permuted random blocks in a 1:1 ratio, stratified for sex and age (<60 or ≥60 years). The PEP self-care group was instructed to use a PEP flute three times per day during the 30 day intervention. MAIN OUTCOME MEASURES Primary outcome was a change in symptom severity from baseline to day 30, as assessed by the self-reported COPD (chronic obstructive pulmonary disease) assessment test (CAT), which was adjusted for baseline values and stratification factors. Participants completed the CAT test questionnaire every day online. Secondary outcomes were self-reported urgent care visits due to covid-19, number of covid-19 related symptoms, and change in self-rated health, all within 30-days’ follow-up. RESULTS 378 participants were assigned to the PEP flute self-care intervention (n=190) or usual care only (n=188). In the PEP self-care group, the median number of days with PEP flute use was 21 days (interquartile range 13-25). For the intention-to-treat population, a group difference was observed in changes from baseline in CAT scores of −1.2 points (95% confidence interval −2.1 to −0.2; P=0.017) in favour of the PEP flute self-care group. At day 30, the PEP flute self-care group also reported less chest tightness, less dyspnoea, more vigour, and higher level of daily activities, but these differences were small, and no consistent effects were seen on the secondary outcomes. No serious adverse events were reported. CONCLUSIONS In community dwelling adults with early covid-19, PEP flute self-care had a significant, yet marginal and uncertain clinical effect on respiratory symptom severity, as measured by CAT scores.