効く（きく）Conjugation
JLPT N5 · Godan verb (Group 1) · Meaning: to be effective
Full conjugation table
| Form | Japanese | Reading |
|---|---|---|
| Dictionary form The base form — casual speech and the stem for many grammar patterns. | 効く | きく |
| masu (polite present) Polite present/future affirmative. | 効きます | ききます |
| masen (polite negative) Polite present negative. | 効きません | ききません |
| mashita (polite past) Polite past affirmative. | 効きました | ききました |
| masen deshita (polite past neg.) Polite past negative. | 効きませんでした | ききませんでした |
| te-form The most versatile form — linking, requests, progressive and more. | 効いて | きいて |
| ta (plain past) Plain past affirmative. | 効いた | きいた |
| nai (plain negative) Plain present negative. | 効かない | きかない |
| nakatta (plain past neg.) Plain past negative. | 効かなかった | きかなかった |
| Potential Ability or possibility — 'can do'. | 効ける | きける |
| Passive Passive voice — 'to be done to'. | 効かれる | きかれる |
| Causative Causative — 'to make/let someone do'. | 効かせる | きかせる |
| Volitional Volitional — 'let's…' or intention. | 効こう | きこう |
| Imperative Imperative — a strong command; used sparingly. | 効け | きけ |
| Prohibitive Prohibitive — 'don't do it!'. | 効くな | きくな |
| Conditional (ba) Hypothetical 'if' — leans written. | 効けば | きけば |
| Conditional (tara) The most versatile everyday 'if / when'. | 効いたら | きいたら |
Example sentences
- この薬は頭痛によく効く。 — This medicine works well for headaches.
- 先生のアドバイスがとても効いた。 — The teacher's advice really made a difference.