regex - PHP preg_match any character except word

To match any character except specified character (in this example "f") I use [^f]+.

But how to match any character except specified word? Something like [^word]+

Example:

haystack: "bla1 bla2 bla3 bla4 hello bla5 bla6 bla7" (haystack contains HTML and newlines)

needle: "bla1 bla2 bla3 bla4 "

So I want to catch everything from start untill "hello"