If you are under the influence of someone or something, you are being affected or controlled by them.

What does it mean by being under the influence?

Phrase used to describe a person who is intoxicated, affected by the use of alcohol or drugs, or a combination of both. See: driving under the influence (DUI)

How do you use under the influence in a sentence?

Often acquisitions are made under the influence of alcohol. Most of them had committed their crime when under the influence of alcohol. He was heavily under the influence of alcohol. Ministers have made it a priority to reduce the number of people who drive under the influence of alcohol or drugs.