どんどん

どんどん says something keeps going, fast and without a pause: "more and more", "one after another". It is an adverb and goes before the verb, most often a verb of change such as なる, ふえる増える or あがる上がる.

A change that is still going on puts the verb in ている, てくる or ていく.

どんどん or だんだん

だんだん is a slow change, one step at a time. どんどん is fast, and it keeps gathering speed.

だんだん only goes with change. どんどん also goes with actions, as in the next section.

• × だんだん食べてください → どんどん食べてください

"Go ahead"

With a request or an invitation, どんどん tells someone not to hold back.

In katakana, どんどんドンドン is the sound of banging on a door or a drum.