Discussion of 中暑 [zhòng shǔ] suffer heatstroke; heatstroke or sunstroke; (TCM) summer-heat stroke - Trainchinese

Can we also say 發痧 ? Yes, you can say 发痧/發痧 (fā shā) to refer to heatstroke, but it's more commonly referred to as 中暑 (zhòng shǔ) in standard usage.

亦能称之为发痧乎？抑或然也。您可称之為發痧（fā shā）以指代中暑，然在规范用語中，中暑（zhòng shǔ）則為其更通行之表述。