症 is built from the 疒 (sickness) and 正 components.
It reads ショウ like 正, as do 政, 定, 証, and 従 — learn 正 once and the family's reading comes with it.
A common word using 症 is 症状 (しょうじょう), meaning “symptoms, condition”.
Kanji that look similar include 疲, 疾, 病, and 疫.
