効く

1. Origins, structure, and basic meaning

• Structure: 効く is read as きく and is an intransitive verb meaning that medicine takes effect or that a seasoning's flavor comes through clearly.
• Basic usage: Medicine beginning to work appears in 薬が効いてくる, while a pronounced pepper flavor appears in 黒こしょうが効いている.

2. Common pitfalls and similar expressions

• Medicine and flavor contexts
  • With medicine it means producing the intended effect, while with seasoning it means that the taste or aroma is clearly perceptible.
• Difference from 効果がある
  • 効果がある generally states that an effect exists, whereas 効く presents the medicine or stimulus as actually working.