I used to get really bad PMT, it's awful, I was awful, I could see I was being awful but it was like you were someone else, I only had it for a few days just before my period was due and once it had passed I was back to my normal happy self much to my husband and daughters relief :(
I tried the evening primrose but didn't seem to do anything I was still dr Jeckall and mr Hyde for those few days, then i found a vitamin/mineral called 'Magnesium-OK' it is specially designed for 'monthly cycles' it has made a really big difference to me and my poor hubby has seen a big difference too. I stock up when Boots have the 3 for 2 sales on I think they sell it in Holland and Barrett as well. whatever she tries, whether it is evening primrose or magnesium-ok she needs to stick with it for at least 2-3 months to give it a chance to work. good luck