Careful not to be taken in by the 'billions' on the packet. They are generally not that stable sat on the shelf and lose potency. So by the time you buy it and then keep it in a cupboard you have no idea how many bacteria each capsule has. Some products are very honest and tell you how many bacteria each will have after losing some of the original potency.

Better go for a broad spectrum one with many types of bacteria.

Lot of shops hard sell expensive brands. Always pushing expensive sachets. Even doctor's giving you expensive ones for the fridge.

I have tried 25 billion ones from overseas for 3-4 months and felt nothing, no difference. Changed brand to cheaper one and system ran like a dream.

Change your diet. More fibre from natural sources, more fruit and vege and brown bread. Give the probiotics the right environment to work in.