Delayed hypersensitivity reaction following lip fillers, not one but four times in the same patient

This case report describes a healthy 25-year-old woman who underwent lip filler augmentation and developed a delayed hypersensitivity reaction not once but four times. A Caucasian female with no medical history presented to the authors in March 2022 with diffuse painful swelling on the left upper lip. Upon examination, the affected area was soft and tender on palpation, with no palpable nodules or lumps. Five days later,the patient reported waking up with tenderness and swelling on her right upper lip this time. Two months after this incident the patient reported that she had experienced two similar incidents at the beginning of May. She again reported waking up with the same symptoms on her right upper lip, which spontaneously resolved within 48 h; and then four days later, she exhibited the same symptoms on her left upper lip. When questioned, she did not recall any flu-like symptoms or signs of COVID-19. She had been vaccinated against COVID-19, but this was long before she had lip fillers injected, namely, in 2020 (two years before the events described here). In this case, no obvious triggering factor was identified, apart from the fact that the patient had been stressed due to upcoming examination. Stress is known to cause flares of autoimmune or infectious diseases, such as herpes simplex virus, through complicated processes that influence immune function. Therefore, stress could have been the triggering factor in the current case.