Try:
Code:
Sub Demo()
Application.ScreenUpdating = False
Dim lRow As Long, lCol As Long, r As Long, c As Long
With ActiveSheet
.UsedRange
With .Cells.SpecialCells(xlCellTypeLastCell)
lRow = .Row
lCol = .Column
End With
For r = 1 To lRow
For c = 2 To lCol
If Application.WorksheetFunction.CountIf(.Range(.Cells(r, 1), .Cells(r, c)), .Cells(r, c).Value) > 1 Then
.Cells(r, c).Font.ColorIndex = 3
End If
Next
Next
End With
Application.ScreenUpdating = True
End Sub