verb
to have an effect, to seem
B1
Wirken means 'to have an effect' or 'to seem'. It's a weak (regular) verb using haben; past participle gewirkt. Non-separable and non-reflexive. Use: wirken auf + accusative to affect something (Das Medikament wirkt auf den Körper), or predicatively without preposition to mean 'seem' (Er wirkt müde).
Examples
Das neue Medikament wirkte besser, nachdem die Dosierung erhöht worden war, sodass die Symptome schneller verschwanden.
The new medicine worked better after the dosage had been increased, so that the symptoms disappeared more quickly.
Seine Worte wirkten beruhigend.
His words had a calming effect.
Das neue Gesetz wirkt sich positiv auf die Umwelt aus.
The new law has a positive effect on the environment.
Details
Mnemonics
Imagine a visible ripple effect — that ripple 'wirkt' (has an effect).
Sounds like English 'work in' — think 'it works in that way' to remember 'wirken' = have an effect.
Notes
Can be used reflexively in the sense 'sich auswirken' (to affect). 'Wirken' has both causative/effect meanings and a perception meaning ('appear/seem'). | Intransitive verb; passive voice conjugations are not applicable. Konjunktiv I Präteritum forms are not used; any Konjunktiv I präteritum entries have been marked 'not applicable'.