Background: Primary hemophagocytic lymphohistiocytosis (pHLH) is a rare and life-threatening disorder, which usually occurs during infancy or early childhood and is characterized by abnormal activation of the immune system. However, the burden of pHLH on children and their families has not been previously evaluated. Methods: This qualitative study investigated the impact of pHLH and its treatment on the physical, emotional, and social well-being of patients and caregivers in the USA and UK using interviews to provide a comprehensive insight from the perspective of the caregivers and young survivors. Results: Twenty-one caregivers were enrolled (median [range] age, 41.1 [26-58] years) and represented 20 patients, four from the UK and 16 from the USA. At enrollment, 17 of the 20 patients were alive with a median [range] age of 12.75 [5-31] years at a mean [range] of 7.8 [0.6-11.6] years after diagnosis. In addition, four adult survivors (median [range] age, 23.3 [21-30] years) were also enrolled (total participants n = 25). From noticing initial symptoms to receiving a diagnosis, caregivers reported a mean (range) of 25.9 (0-258) months. pHLH and its treatment had a substantial and long-lasting impact on patients and caregivers, affecting their physical, emotional and social well-being, family relationships, friendships, and ability to work and study. Many of the experiences reported were negative, even after curative treatment, and some participants experienced long-lasting physical and emotional issues. The most noticeable impact of pHLH for patients was on their physical well-being, whereas for caregivers it was emotional well-being. Across all participants there was a sense of isolation due to the illness and its treatment, particularly regarding the patient being immunocompromised and the fear of infection. Areas having a major impact and considered in need of improvement included: delays in diagnosis, lack of patient-specific information on pHLH and a lack of support and understanding about the condition. Conclusions: pHLH placed a substantial burden on patients and caregivers, which for some were long-lasting. This was compounded by the lack of awareness and understanding of pHLH by healthcare professionals, and a lack of accessible information for those affected by pHLH.