Don't touch the open sore - it can easily get infected.
Tips
usage
疮 is a general term for skin lesions, ulcers, and boils. Compounds include 疮疤 (scar), 疮口 (open sore / wound opening), and 疮痍 (wounds and trauma, often used figuratively for devastation).
The sickness radical wraps the top-left - a person lying on a bed turned ninety degrees, the classical icon for illness. It puts 疮 squarely in the disease family with 病 (illness), 疼 (ache), 疫 (epidemic), 痒 (itch), 疤 (scar). The wrap signals 'a condition of the body'.
Inside 仓 supplies the sound - cāng drifting to chuāng through the well-attested c→ch shift seen in 创 (chuàng, create) and 沧 (cāng). Same phonetic series collects wound-and-edge meanings; here it gives the reading for a sore, ulcer, or skin lesion.
