瘙 almost never appears alone in modern Chinese — it's bound to 痒 in 瘙痒 (sàoyǎng) 'to itch / itching'. In medical and dermatology contexts you'll also see 瘙痒症 'pruritus'. Taiwanese pronunciation is sometimes [sāo].
memory
The 疒 (sickness) radical on the left signals all three meanings — 瘙 is medical-itching, not casual scratching. Casual 'I want to scratch' uses 痒 (yǎng) on its own.
