Propranolol-resistant IH have also been described as an absence of treatment response either in the proliferative phase or during the post-proliferative phase, after at least 4 weeks of oral propranolol at dosage of ≥2 mg/kg/day.[44] It is reported to occur at a frequency of 0.9% (10/1130). Of the 10 such cases reported from France, 8 had haemangioma on the face. Five children were in the proliferative phase (≤4.2 months) and showed continued growth. The remaining 5 (≥8 months) children, who did not show any decrease in the IH size, were in the post-proliferative phase.[44] This phenomenon needs to be investigated in a large scale studies in order to understand the different factors which influence the treatment outcome in children with IH.