涨

zhàng describes bodies, organs, or faces distending. The two highest-frequency contexts: (1) bloating — a full belly, a swollen leg; (2) flushing — a face going hot and red. Common compounds: 涨红 (to flush red), the four-character 头昏脑涨 (head swimming and swollen — after exhaustion or too much information). The body-swelling sense is more often written with the dedicated char 胀 (with the flesh radical) — 热胀冷缩 'expand with heat, contract with cold' uses 胀, but 涨 survives as a variant in fixed expressions.

Default to zhǎng (rise) for anything about prices, water levels, social-media metrics. Switch to zhàng only when something is physically swelling or a face is going red — a body / object getting bigger, not a level going higher.