Sub FindStrings()
Dim RX As Object
Dim rngN As Range, c As Range
Set RX = CreateObject("VBScript.RegExp")
RX.IgnoreCase = True
RX.Pattern = Application.TextJoin("|", 1, Sheets("Words").Range("A2", Sheets("Words").Range("A" & Rows.Count).End(xlUp)))
Set rngN = Range("N2", Range("N" & Rows.Count).End(xlUp))
rngN.Interior.Color = xlNone
For Each c In rngN
If RX.Test(c.Value) Then c.Interior.Color = vbRed
Next c
End Sub