A boy in his middle childhood with severe haemophilia reported with facial swelling following dental treatment for a carious upper primary molar done at a private dental clinic elsewhere. On presentation, he had a large, tense and tender swelling of the left cheek and a haematoma on the buccal mucosa adjacent to the treated tooth. The child was found to have a low haemoglobin level. He was taken for an emergency procedure under general anaesthesia for dental extraction with incision and drainage, and simultaneously underwent packed cells and factor replacement. He recovered in the ward postoperatively with no complications and with a gradual reduction of the swelling. This report highlights the importance of caries prevention in children, especially those with haemophilia. They need to be educated about restricting cariogenic foods in their diet and maintaining good oral hygiene. Management of such patients should be carefully coordinated to minimise undesirable outcomes.