STUDY QUESTION Does the disease label polycystic ovary syndrome' (PCOS) have an impact on desire for medical testing and psychosocial outcomes SUMMARY ANSWER When given the disease label PCOS in a hypothetical scenario, participants had higher intention to have an ultrasound, perceived the condition to be more severe and had lower self-esteem than those not given the disease label. WHAT IS KNOWN ALREADY Widening diagnostic criteria and improved imaging sensitivity have increased the number of reproductive-aged women diagnosed with PCOS from 4% to 8% to up to 21%. The uncertain clinical benefit of knowing this diagnosis needs to be weighed against the potential for poor psychological outcomes in women labelled with PCOS. STUDY DESIGN, SIZE, DURATION This experimental online study randomised 181 young women to receive one of four hypothetical scenarios of a doctor's visit in a 2 (PCOS disease label versus no disease label) x 2 (information about unreliability of ultrasounds in clarifying diagnosis versus no information) design. PARTICIPANTS/MATERIALS, SETTING, METHODS Participants were university students (mean age: 19.4). After presenting the scenario, intention to have an ultrasound, negative affect, self-esteem, perceived severity of condition, credibility of the doctor and interest in a second opinion were measured. Participants were then presented with a second scenario, where the possibility of PCOS overdiagnosis was mentioned. Change in intention and perceived severity were then measured. MAIN RESULTS AND THE ROLE OF CHANCE Participants given the PCOS label had significantly higher intention to have an ultrasound (mean = 6.62 versus mean = 5.76, P = 0.033, 95% CI(difference) = 0.069-1.599), perceived the condition to be more severe (17.17 versus 15.82, P = 0.019, 95% CI(difference) = 0.229-2.479) and had lower self-esteem (25.86 versus 27.56, P = 0.031, 95% CI(difference) = -3.187 to -0.157). After receiving overdiagnosis information, both intention and perceived severity decreased, regardless of condition (both P < 0.001). LIMITATIONS, REASONS FOR CAUTION This study used hypothetical scenarios; it is likely that for women facing a real diagnosis of PCOS, outcomes would be more affected than in the current study. The hypothetical design, however, allowed the symptoms and risks of PCOS to be held constant across conditions, the impact on intention and psychosocial outcomes directly attributable to the effect of the disease label. WIDER IMPLICATIONS OF THE FINDINGS These findings demonstrate the potential negative consequences of PCOS labelling. It is crucial we consider the impact of the label before diagnosing more women with PCOS when clinical benefit of this diagnosis is uncertain.