noun
Common everyday term for pain-relieving medicine, such as over-the-counter tablets or prescribed analgesics.
頭が痛いので痛み止めを飲んだ。
I had a headache, so I took a painkiller.
この痛み止めはよく効く。
This painkiller works well.
More formal or medical term for analgesic, often used in clinical contexts.
Compound of 痛み (itami, 'pain') + 止め (dome, 'stopping'), from the verb 止める (tomeru, 'to stop').