I have to take them for period pains and I have to make sure I take them regularly from the first sign of pain for about 4 days else I am in absolute agony.
They are working in that I am not really in any pain but they do make me feel a bit light headed and like I have a headache. Seems a bit odd that taking a painkiller can give you a headache, but my mum said she thinks she read that it was a side effect.