Background <p>Primary immune thrombocytopenia (ITP) adversely impacts a patient’s health-related quality of life (HRQoL).</p> Objective <p>This study explored patients’ experiences with signs, symptoms, and impacts of ITP and updated the conceptual disease model for HRQoL in patients with ITP.</p> Methods <p>Adult patients with ITP were included in the study. Patients with any comorbidity where fatigue was a key symptom (e.g., anemia) were excluded. A concept elicitation interview assessed signs, symptoms, and impacts from the patients’ perspective, and cognitive debriefing assessed the validity of the selected patient-reported outcome instruments (ITP-Patient Assessment Questionnaire, Patient Global Impression of Severity of Fatigue, Patient Global Impression on Severity, and Patient Global Impression on Change scales). Symptoms/impacts mentioned by ≥ 50% of patients and a “bothersomeness” rating of ≥ 5 were considered salient. The preliminary conceptual model was updated based on the concepts reported by more than one patient.</p> Results <p>A total of 18 patients (mean age 42.7 ± standard deviation 14.7 years; female 78%) were interviewed. Six salient symptoms included fatigue (94%; <i>n </i>= 17), bruising (83%; <i>n</i> = 15), petechiae (72%; <i>n</i> = 13), difficulty staying awake during the day, difficulty falling asleep, and difficulty staying asleep (all symptoms related to sleep: 50%, <i>n</i> = 9). Six key impacts that emerged included those on work (72%;<i> n</i>&#xa0;=&#xa0;13), worry and fear (67%; <i>n</i> = 12), limited physical or sporting activities, the perceived need to be cautious to avoid getting hurt, and family, friends, and social life (all 56%; <i>n</i> = 10).</p> Conclusion <p>This study highlighted six key symptoms of ITP and its impacts on patients with ITP. The concept elicitation findings were used to update the conceptual model, and—during cognitive debriefing—patients found the patient-reported outcome instruments easy to understand and relevant to their experience.</p>