“热晕”在英语中常见的表达有 “faint from the heat”、“be overcome by the heat” 或 “get heatstroke” ，具体使用可根据语境选择：
“faint from the heat”：强调因高温而晕倒、失去意识。例如：The old man fainted from the heat on the hot summer day.（在那个炎热的夏日，老人因高温晕倒了。）
“be overcome by the heat”：侧重于表达被高温打败、难以承受，出现身体不适等状况。例如：She was overcome by the heat and had to sit down.（她被高温弄得难以忍受，不得不坐下来。）
“get heatstroke”：指中暑这一医学概念，“热晕”如果是中暑导致，就可以用这个表达。例如：He got heatstroke while working outside in the sun.（他在户外阳光下工作时中暑了 。 ）