This is the 497th most frequent Japanese word.
飲ん
The Japanese word "飲ん" is the stem form of "飲む," meaning "to drink."
The word '飲ん' is used in its standard form as a verb stem, expressing the action of drinking.
私は水を飲んでいます。
I am drinking water.
Here, '飲ん' is part of a prohibition phrase, stating a restriction on the action of intake (medication in this case).
彼は薬を飲んではいけません。
He must not take medicine.
In this example, '飲ん' is used as part of a completed action, linked to the subsequent phrase by the particle 'で'