Abstract Ichthyosis follicularis alopecia and photophobia (IFAP) syndrome is a rare, X-linked inherited disorder caused by pathogenic mutations in the MBTPS2 gene. Seventy cases have been reported previously. The phenotypic spectrum varies, but IFAP consistently causes noninflammatory follicular keratoses, nonscarring alopecia and progressive corneal scarring. A 7-year-old boy, with IFAP syndrome associated with neurodevelopmental delay, chorioretinal coloboma and poor growth requiring gastrostomy, presented with a 4-week history of worsening flexural erythema and pain. Trials of topical steroids with fucidic acid, nystatin and oral penicillin had proven ineffective. On initial evaluation he had florid painful flexural erythema with surrounding crusting and scale. The Nikolsky sign was negative. He was systemically unwell with fever, dehydration and malaise requiring hospital admission. Laboratory evaluation demonstrated leucocytosis with neutrophilia and peak CRP of 100. He was treated empirically for bacterial superinfection including Staphylococcus scalded skin syndrome with intravenous clindamycin. With no appreciable improvement after 48 h, antimicrobial therapy was extended to include fluconazole and aciclovir. After 5 days, he continued to be febrile and systemically unwell with extensive yellow-brown crusting most marked at the flexural areas, and clindamycin was switched to piperacillin/tazobactam to provide antipseudomonal coverage. Skin swab cultures subsequently confirmed heavy growth of Pseudomonas aeruginosa. Within 48 h there was marked clinical improvement. He was discharged home to complete a course of oral antibiotics. This case highlights the importance of early consideration of Pseudomonas infection as a cause of subacute flexural exacerbations, particularly in those with skin barrier abnormalities, including inherited ichthyoses.