Background Patients prescribed supplemental oxygen (O2) therapy face challenges as they adjust to being constantly “tethered” to an oxygen delivery device. Informal caregivers (ICs) of patients with pulmonary fibrosis (PF) face their own, often overlooked hardships when O2 is brought into their home and added to their lives. Our aim was to understand the multiple effects of supplemental oxygen therapy on ICs of patients with PF. Methods We conducted single, semi-structured telephone interviews with twenty ICs of patients with PF who were using O2 for at least 8 months. We performed a qualitative, content analysis based in grounded theory to examine data across subjects. Results ICs initially reacted to O2 with trepidation and sadness as they came to recognize the changes it would cause in the lives of their patient-loved one (PLO). ICs recognized both beneficial and negative effects of O2 on their PLOs. ICs also realized that O2 created significant changes in their own lives, including introducing new roles and responsibilities for them, altering their home environments and significantly impacting their relationships with their PLOs. Although O2 was a tangible and constant reminder of disease progression, over time ICs were able to adapt and accept their new lives with O2. Conclusion ICs of patients with PF experience many life changes when their PLO is prescribed O2. Having O2 prescribers anticipate and recognize these challenges provides an opportunity to give support and guidance to ICs of PF patients who require O2 in the hopes of limiting the negative impact of O2 on their lives. Trial registration Clinicaltrials.gov , registration number NCT01961362 . Registered 9 October 2013.