Vascular compromise and resulting ischaemic injury are known rare complications of cosmetic filler injections. Most hyaluronic acid vascular compromises present early and can be treated effectively by hyaluronidase. Here we present a case of ischaemic wound and mucosal necrosis after cosmetic facial hyaluronic acid injection that appeared within hours of injection but was not diagnosed and treated for 5 days. At day 5, the patient was treated with hyaluronidase injection immediately followed by 14 sessions of daily hyperbaric oxygen therapy (HBOT). Despite the delayed treatment, the patient had essentially complete recovery and the hyperbaric therapy was overall well-tolerated. Our case report suggests that hyaluronidase injection with concurrent daily HBOT sessions may be effective to allow recovery from late-presenting filler ischaemic complication. Furthermore, given the safety profile of HBOT, we suggest a more deliberate approach to this modality as a therapeutic adjunct by cosmetic practitioners when similar complications arise.