<p>Breast augmentation surgery is the most common cosmetic procedure among women worldwide. Aquafilling has been widely used in breast augmentation surgeries over the past decade, however, some patients who undergo this procedure have begun to report complications. We report a case of massive, culture-negative breast abscess occurring during lactation after breast augmentation with Aquafilling, resulting in significant breastfeeding difficulties. A 33-year-old female underwent Aquafilling injection for breast augmentation in July 2022. In September 2023, she developed a massive, culture-negative breast abscess during lactation, resulting in difficulty breastfeeding. Ultrasound and MRI revealed wrinkles and thickening of the implant edge, with possible rupture. Initial treatment included antibiotics, needle aspiration, etc. Due to infection, bilateral implant removal surgery was chosen. The patient recovered without any further complications except asymmetry. The incidence of complications related to Aquafilling-mediated breast augmentation is increasing, with the most prominent complications being infection and breast induration. In this scenario, lactating women who undergo Aquafilling injection for breast augmentation are at increased risk of lactational mastitis, leading to breastfeeding difficulties. This case illustrates that Aquafilling injection for breast augmentation may be associated with the development of a culture-negative abscess during lactation, complicating breastfeeding and potentially necessitating surgical removal of the filler material. Clinicians should maintain a high index of suspicion for filler-induced inflammation in lactating women with breast swelling following copolyamide gel injection.</p>