She was dazed from the medication.

Literal

She [topic-は] medicine [because of-の] [purpose-ため] dazed was.

薬のためぼうっとしていた — ぼうっと is a mimetic adverb for being dazed, spaced out, or unfocused. のため marks the cause. ぼうっとする describes a hazy mental state.